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Cellulose micro- and nanofibers (CNFs) are commonly regarded as “greener” than petro-based materials. The high energy input that their production still demands, along with the use of chemicals or heat in some pretreatments, asks for a critical view. This paper attempts a life cycle assessment of CNFs produced from bleached hardwood kraft pulp via three different pre-treatments before mechanical homogenization. First, a fully mechanical route, based on a Valley beating pre-treatment. Second, an enzymatic route, based on endoglucanases and requiring certain temperature (~50 °C). Third, a TEMPO-mediated oxidation route, considering not only the impact of the chemical treatment itself but also the production of TEMPO from ammonia and acetone. The main output of the study is that both, mechanical and TEMPO-mediated oxidation routes, present lower impacts than the enzymatic pre-treatment. Although the mechanical route presents slightly milder contributions to climate change, acidification, eutrophication, and other indicators, saying that TEMPO-mediated oxidation is environmentally unfeasible should be put under question. After all, and despite being disregarded in most assessment publications up to date, it is the only well-known way to selectively oxidize primary hydroxyl groups and thus producing kinds of CNFs that are unthinkable by other ways.

Environment and sustainability are keywords on the world agenda, envisioning human welfare and protection of the ecosystems. The development of biobased products and materials is a vital contribution to a global model of sustainable development, to reduce the dependence on fossil resources and to contribute to mitigate climate changes and the pollution issues in general. Natural fiber-reinforced composites, reported in countless academic studies as alternative to synthetic fiber-reinforced composites, are a step forward in this direction, with some products already reaching a commercial status. However, most polymeric matrices typically employed for that purpose are still primarily based on petrochemical resources. Thus, the quest for fully biobased materials, from renewable origin, and with environmentally safe end-of-life disposals urges. In this perspective, the present dissertation aims at the development of sustainable composites made of biobased thermoplastic matrices, namely poly(lactic acid) (PLA), poly(hydroxybutyrate) (PHB) or cellulose acetate butyrate (CAB), with high cellulose incorporation (obtained from bleached eucalyptus kraft pulp (BEKP)), produced by melt mixing methods and processed by injection-molding, which are processes commonly employed at an industrial level. Firstly, a mechanical treatment (micronization) was investigated as a green strategy to avert fiber agglomeration and to enhance the overall properties of the composites (Chapter 2). The influence of the load (10.0 to 40.0 wt.%, relative to the weight of the matrix + reinforcement) and aspect ratio (in the range from 11.0 to 28.9) of the mechanically treated fibers was evaluated in PHB- and PLA-based composites. It was found that increasing the fiber load raised the tensile and flexural moduli, as well as the tensile strength of the composites, while decreasing their elongation at the break and melt flow rate (MFR). The reduced aspect ratio of the micronized fibers improved their embedment in the matrices, particularly in composites with PHB, leading to superior mechanical performance and lower water uptake when compared with the composites with non-micronized pulp fibers. With micronization established as a promising strategy to produce these composites, the second study focused on the use of additives from biobased origin to tackle the aforementioned limitations, namely the low MFR and extensibility, as well as other key properties such as the impact strength (Chapter 3). Two different additives, more specifically an epoxidized linseed oil (ELO) and a surfactant mainly composed of sunflower oil methylglucamide, viz. GlucoPure® Sense (GPS), were tested in different percentages (0.0 to 7.5 wt.%, relative to the weight of the composite) in composite formulations of PLA or PHB reinforced with micronized pulp fibers (40.0 wt.%, relative to the weight of the matrix + reinforcement). Both additives showed a plasticizing effect, which led to a decrease in the Young’s and flexural moduli and strengths. Simultaneously, the elongation and flexural strain at break were considerably improved on some formulations. The MFR was also remarkably improved with the incorporation of the additives. In the PHB-based composites, an increment of 230% was observed upon incorporation of 7.5 wt.% ELO and, in composites based on PLA, an increase of around 155% was achieved with the addition of 2.5 wt.% GPS. ELO also increased the impact strength to a maximum of 29 kJ.mˉ², in formulations with PLA. The biodegradability in compost medium, conducted at room temperature, was also assessed and, for most composites, a faster degradation rate was observed for the composites comprising the additives, reaching, in the case of PHB composites with GPS, a noteworthy weight loss over 75% by the end of 6 months. The final study regarding the preparation and characterization of composites concerns the production of All-Cellulose Composites (ACCs) of CAB reinforced with micronized pulp fibers (40.0 wt.%, relative to the weight of the matrix + reinforcement), and plasticized with ELO (0.0 to 30.0 wt.%, relative to the weight of the composite) (Chapter 4). The use of this additive decreased the glass transition temperature of the obtained composites without compromising their thermal stability. Moreover, an 84-fold increase on the MFR was achieved with 30.0 wt.% ELO and, growing amounts of the additive caused an augment on the elongation and flexural strains at break, as well as an improvement on the impact strength. Therefore, these results evince a remarkable improvement on the ACCs processability and performance upon addition of a biobased and cost-effective plasticizer. Finally, a techno-economic assessment was performed to evaluate the viability of an industrial facility for the production of composites of PHB, PLA or CAB reinforced with micronized fibers and, optionally, an additive (Chapter 5). Taking as an example a composite of PLA with 30.0 wt.% of micronized fibers and 5.0 wt.% of ELO, the 15-year net present value of 5.7 M€, the 15-year internal rate of return of 25.7% and a payback of 3.9 years prove the economic viability of the project. In sum, this thesis demonstrates the advantages of employing a micronization procedure to overcome some of the most reported limitations on the use of cellulosic fibers as reinforcements in composites. Moreover, environmentally friendly additives were successfully applied to improve the processability and performance of the composites, envisioning applications in the automotive industry, electronic devices, everyday commodities, among many others. Meio ambiente e sustentabilidade são palavras de ordem no panorama global, que visam a promoção do bem-estar humano e a proteção dos ecossistemas. Neste sentido, a criação e utilização de produtos e materiais de origem biológica é vital para um modelo de desenvolvimento sustentável, de forma a reduzir a dependência de recursos fósseis e de contribuir para a mitigação das alterações climáticas e dos problemas de poluição ambiental em geral. Os compósitos reforçados com fibras naturais, reportados em inúmeros estudos científicos como alternativa aos compósitos convencionais reforçados com fibras sintéticas, são um avanço significativo nessa direção, tendo alguns destes materiais alcançado a comercialização e distribuição no mercado. Contudo, a grande maioria das matrizes poliméricas normalmente utilizadas para este fim ainda são de origem fóssil. Assim, urge o interesse e a necessidade por materiais de origem inteiramente renovável e cujo impacto no meio ambiente seja mínimo ou nulo. Nesta perspetiva, a presente dissertação visa o desenvolvimento de compósitos sustentáveis, constituídos por matrizes termoplásticas de base biológica, nomeadamente o poli(ácido láctico) (PLA), o poli(hidroxibutirato) (PHB) ou o acetato butirato de celulose (CAB), com elevada incorporação de fibras de celulose (obtidas a partir de fibra kraft branqueadas de eucalipto (BEKP)), produzidos por mistura a quente e processados por moldagem por injeção, os quais são processos usados a nível industrial. Em primeiro lugar, foi estudado um tratamento mecânico (micronização) como estratégia amiga do ambiente para melhorar a dispersão das fibras nas matrizes poliméricas, evitando a sua aglomeração, por forma a melhorar as propriedades dos compósitos (Capítulo 2). Neste estudo foi avaliada a influência da carga (10,0 a 40,0%, em relação à massa da matriz + reforço) e da razão de aspeto (11,0 a 28,9) das fibras micronizadas em compósitos de PHB e PLA. Os resultados mostraram que o aumento da carga das fibras aumentou a força de tração e os módulos de tração e flexão e diminuiu o alongamento à quebra, e o índice de fluidez (MFR) dos compósitos. As fibras com menor razão de aspeto apresentaram uma melhor dispersão nas matrizes poliméricas, principalmente com o PHB, melhorando o desempenho mecânico e diminuindo a absorção de água destes compósitos, quando comparados aos compósitos com fibras de celulose não micronizadas. Com o processo de micronização estabelecido como uma estratégia promissora para a produção destes compósitos, o segundo estudo focou-se na utilização de aditivos de base biológica para ultrapassar algumas das limitações supracitadas, nomeadamente o baixo índice de fluidez e alongamento à quebra, assim como outras propriedades tais como a força de impacto (Capítulo 3). Foram testados dois aditivos distintos, mais especificamente um óleo de linhaça epoxidado (ELO) e um tensioativo constituído maioritariamente por metilglucamida com óleo de girassol, GlucoPure®Sense (GPS), em percentagens de 0,0 a 7,5% (em relação à massa do compósito), em formulações de PLA ou PHB com fibras de celulose micronizadas (40,0%, em relação à massa da matriz + reforço). Ambos os aditivos mostraram um efeito plastificante, o que resultou numa diminuição dos módulos e forças de tração e flexão. Simultaneamente, o alongamento e flexão à quebra melhoraram significativamente em algumas formulações. O MFR também melhorou com a incorporação dos aditivos. Nos compósitos à base de PHB, observou-se um aumento de 230% com a incorporação de 7,5% de ELO e, nos compósitos à base de PLA, obteve-se um aumento de cerca de 155% com a adição de 2,5% de GPS. O ELO também aumentou a resistência ao impacto para um valor máximo de 29 kJ.mˉ², em compósitos com PLA. Ensaios de biodegradação, em meio de compostagem à temperatura ambiente, mostraram que a taxa de degradação é superior para os compósitos com aditivos, atingindo no caso dos compósitos de PHB com GPS, uma perda de massa de 75% ao fim de 6 meses. No que diz respeito ao desenvolvimento de novos materiais compósitos, foram ainda produzidos e caracterizados compósitos constituídos unicamente por celulose ou seus derivados (ACCs, do inglês All Cellulose Composites), nomeadamente por CAB reforçado com fibras micronizadas (40,0%, em relação à massa da matriz + reforço) e plastificados com ELO (0,0 a 30,0%, em relação à massa do compósito) (Capítulo 4). A utilização deste aditivo diminuiu a temperatura de transição vítrea dos compósitos sem comprometer a sua estabilidade térmica. Adicionalmente, quantidades crescentes de ELO causaram um aumento no alongamento e flexão à quebra, uma melhoria na resistência ao impacto e, para 30,0% de ELO, um aumento de 84 vezes no MFR. Assim, estes resultados evidenciaram uma melhoria notável no processamento e desempenho dos ACCs após adição de um plastificante de base biológica e de baixo custo. Por fim, foi realizada uma análise técnico-económica para avaliar a viabilidade de uma instalação industrial de produção de compósitos de PHB, PLA ou CAB reforçados com fibras micronizadas e, opcionalmente, um aditivo (Capítulo 5). Tendo como exemplo um compósito de PLA com 30,0% de fibras micronizadas e 5,0% de ELO, o valor atual líquido (15 anos) de 5,7 M€, a taxa interna de rentabilidade (15 anos) de 25,7% e um tempo de retorno do investimento de 3,9 anos comprovam a viabilidade económica do projeto. Em suma, esta tese demonstra as vantagens de utilizar o processo de micronização para superar algumas das limitações mais reportadas no uso de fibras de celulose como materiais de reforço em compósitos. Além disso, foram aplicados com sucesso dois ativos de base biológica para melhorar o processamento e desempenho destes compósitos, tendo em vista aplicações na indústria automóvel, dispositivos eletrónicos, utilidades do dia-a-dia, entre muitas outras. Programa Doutoral em Biorrefinarias

The aim of this study was to investigate a possibility of synthesis of porous ceramics with controlled open porosity, which could be used as sorbents and catalyst supports. Two organic additives were used to obtain open porosity: polystyrene beads and cellulose fibers, which are mixed with kaolin clay powder and the appropriate water content. Samples were sintered at 1050?C for 1 h. Characterization of the obtained products included X-ray powder diffraction analysis (XRPD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and elemental CHNS analysis. In addition, porosity was examined by quantification of visual information. The specific surface areas were determined by the Brunauer?Emmett?Teller (BET) method. Also, density and compressive strength of the obtained samples were assessed. It was determined that by sintering, the organic component completely leaves the system. For samples prepared with polystyrene beads and with cellulose fibers, satisfactory mechanical properties were obtained: compressive strengths were 1.42 and 1.56 MPa, respectively. It was noted that significantly higher open porosity was obtained by using polystyrene beads as a sacrificial template (porosity of ~56 %) instead of cellulose fibers (porosity of ~6 %).

In this work, bio-based hydrogel composites of xanthan gum and cellulose fibers were developed to be used both as soil conditioners and topsoil covers, to promote plant growth and forest protection. The rheological, morphological, and water absorption properties of produced hydrogels were comprehensively investigated, together with the analysis of the effect of hydrogel addition to the soil. Specifically, the moisture absorption capability of these hydrogels was above 1000%, even after multiple dewatering/rehydration cycles. Moreover, the soil treated with 1.8 wt% of these materials increased the water absorption capacity by approximately 60% and reduced the water evaporation rate, due to the formation of a physical network between the soil, xanthan gum and cellulose fibers. Practical experiments on the growth of herbaceous and tomato plants were also performed, showing that the addition of less than 2 wt% of hydrogels into the soil resulted in higher growth rate values than untreated soil. Furthermore, it has been demonstrated that the use of the produced topsoil covers helped promote plant growth. The exceptional water-regulating properties of the investigated materials could allow for the development of a simple, inexpensive and scalable technology to be extensively applied in forestry and/or agricultural applications, to improve plant resilience and face the challenges related to climate change.

In order to improve and strengthen the importance of environmental protection and waste management in practice, it is necessary to use waste as a raw material for the production of new materials in a circular economy. With the development of textile technology and materials, it is now possible to produce biodegradable materials, which are an important step in the implementation of waste management and thus environmental protection. In this aspect, the idea of developing materials from textile industrial waste as a raw material for personal use was initiated. The aim of this work is to study the mechanical properties and biodegradability of composites made from shredded modal fibers mixed with thickeners, with and without chitosan as an additional additive, in order to obtain better biodegradable properties in use. Also, a rheological analysis of three types of thickeners with different raw material compositions was carried out, of which carboxymethylcellulose was found to be the most suitable for testing the dry matter content and blending with modal as man-made cellulose fibers. The following tests of the structure of the composites formed, such as surface analysis with a scanning electron microscope, tensile strength with a universal strength tester, while the biodegradability of the samples were carried out by burying them in the soil. The obtained results show that the mechanical properties of the composite structure were improved and the components of the tested composite were almost completely degraded within a degradation period of 50 days, which proves the biodegradability.

Nowadays, due to their natural availability, renewability, biodegradability, nontoxicity, light weight and relatively low cost, natural fibers, especially lignocellulosic fibers, present attractive potential to substitute non-eco-friendly synthetic fibers. In this study, Ziziphus jujuba fibers were used, thanks to their low lignin content, as an alternative of renewable resource for the production of cellulosic fibers with suitable characteristics and minimal time and energy consumption. In fact, due to their valuable chemical composition, it was possible to remove the amorphous fractions and impurities from the fiber surface by applying ultrasounds coupled with alkaline treatment (80 °C, 5 wt.% NaOH), followed by a bleaching step. The efficient dissolution of the noncellulosic compounds was confirmed by Fourier Transform Infrared Spectroscopy (FTIR). The resulted increase in the crystallinity index (from 35.7% to 57.5%), occurred without impacting the crystalline structure of the fibers. The morphological analysis of the fibers evidences the higher surface area of the obtained fibers. Based on the obtained results, Ziziphus jujuba fibers were found to present a suitable sustainable source for the production of cellulosic fibers.

Microfibers (MFs) are ubiquitous in natural environments and are considered as an anthropogenic litter that has become a global concern. Approximately 2 million tons of MFs are released into the ocean every year and once in the marine environment, it can be hypothesized that their accumulation and transport are largely controlled by oceanographic processes. We collected water column samples for MFs separation and polymeric characterization at 38 stations located in the Central-Western Mediterranean Sea. The aim of our study was to investigate MFs distribution in different water masses and transport through different Mediterranean basins. MFs were detected in all samples with a median concentration of 3.8MFs/L. Polymeric analysis highlighted cellulosic-based fibers as the dominant polymer (85%) over synthetic fibers (5%) and processed cellulose (8%), while animal fibers were detected occasionally. MF concentration was locally characterized by vertical variations according to water masses, and by changes in size, with surface and deep fibers being longer and larger than mid-water fibers. Mediterranean surface waters showed homogeneous MF content (range 3.0-4.9MFs/L), while intermediate and deep waters were characterized by opposite trends. Intermediate-waters showed decreasing MFs concentration moving from the Eastern to the Western Mediterranean basin (9.6-1.6MFs/L) while MF content increased in deep waters at the same stations (3.7-9.1MFs/L). Along the Sardinia Channel, we estimated a negative MF flux of 6 Trillion MF/day entering the Tyrrhenian Sea at intermediate depths, and a positive flux of 12 Trillion MF/day in the deep-water mass. We also estimate a 10-fold flux of synthetic fibers leaving the Tyrrhenian Sea, compared with the daily inflow. Our findings suggest that: i)there is a predominant MFs input on surface waters by atmospheric deposition; ii)MFs vertical distribution is size-dependent; iii)MFs transport between Mediterranean basins is mediated by Levantine waters; iv)a potential export of MFs to deep waters occurs in the Tyrrhenian Sea. Also see: https://micro2022.sciencesconf.org/426893/document, In MICRO 2022, Online Atlas Edition: Plastic Pollution from MACRO to nano

Measurements of nanocellulose size usually demand very high-resolution techniques and tedious image processing, mainly in what pertains to the length of nanofibers. Aiming to ease the process, this work assesses a relatively simple method to estimate the dimensions of nanocellulose particles with an aspect ratio greater than 1. Nanocellulose suspensions, both as nanofibers and as nanocrystals, are subjected to dynamic light scattering (DLS) and to field-emission scanning electron microscopy (FE-SEM). The former provides the hydrodynamic diameter, as long as the scatter angle and the consistency are adequate. Assays with different angles and concentrations compel us to recommend forward scattering (12.8°) and concentrations around 0.05–0.10 wt %. Then, FE-SEM with magnifications of ×5000–×20,000 generally suffices to obtain an acceptable approximation for the actual diameter, at least for bundles. Finally, length can be estimated by a simple geometric relationship. Regardless of whether they are collected from FE-SEM or DLS, size distributions are generally skewed to lower diameters. Width distributions from FE-SEM, in particular, are well fitted to log-normal functions. Overall, while this method is not valid for the thinnest fibrils or for single, small nanocrystals, it can be useful in lieu of very high-resolution techniques.

Miscanthus × giganteus is a fast-growing and high-yielding perennial grass widely available in North America. This research investigated two pre-treatment techniques to extract cellulose fibers and lignin from miscanthus biomass and determined their potential applications. The first study investigated an ultrasound-assisted-alkali-urea (UAAU) pre-treatment for enhanced delignification of miscanthus. Sonication time, NaOH concentration, and urea concentrations were optimized using a response surface methodology. The UAAU method extracted up to 52% (w/w) cellulose fibers from miscanthus at 5% NaOH, 1.75% urea, and 20 min sonication, resulting in cellulose fibers of higher crystallinity, and thermal stability than the untreated samples. In the second study, a binary enzyme (BE) cocktail (cellulase and laccase) was investigated for the extraction of cellulose fibers from the miscanthus biomass. The cellulase-laccase cocktail extracted up to 47% (w/w) cellulose fibers, whereas the cellulase or laccase treatments alone resulted in 38% (w/w) or 36% (w/w), respectively. Paper-sheets prepared from the fibers from the BE treatment showed higher mechanical properties and water absorption capacity than those prepared from that of the single-enzyme treatments. In the third study, the extracted lignin was subjected to hydroxyethylation by ethylene carbonate, followed by esterification with propionic acid. The esterified lignin was then co-dissolved with cellulose acetate in acetone and applied as a coating on the paper-sheets. The coated paper-sheets exhibited significantly higher hydrophobicity and tensile strength, while lower water vapour transmission rate than the uncoated samples. In the fourth study, an ethyl cellulose-based nonwoven filter (NWF) was developed using a free-surface electrospinning technique. The nonwoven was loaded with silver nanoparticles (AgNPs) synthetized through reducing Ag+ with the extracted lignin. The filtration test against NaCl aerosols (≥ 0.3 µm) yielded desired performance with filtration efficiency (>99%), pressure drop (0.077 Pa-1) at RH (25 ± 2% and > 90%). At 60 min contact time, AgNPs loaded NWFs exhibited antiviral activity against a surrogate virus, bacteriophage Φ6, with more than 5 log10 (PFU/mL) reduction. Overall, this research shows that UAAU and BE pre-treatments could effectively extract cellulose fibers and lignin from miscanthus biomass, while the resulting fibers and lignin could be used for hydrophobic paper-sheet and antiviral mask filter applications. Barrett Sustainable Food Engineering Grant, School of Engineering, University of Guelph, Canada; COVID-19 Research Development and Catalyst Fund, University of Guelph, Canada 2023-08-31

V prvem delu magistrskega dela sem raziskoval zamreževanje komercialne natrijeve soli karboksimetil celuloze z uporabo različnih zamreževalnih reagentov na osnovi naravnih dikarboksilnih kislin z različnimi dolžinami verig (citronska kislina, jantarna kislina in jabolčna kislina) ter 2,5-furandikarboksilne kisline, ki so sintetizirane iz biomase. Reakcije zamreževanja so bile izvedene pod različnimi pogoji (reakcijski čas in temperatura sušenja ter različna množinska razmerja med celuloznim derivatom in uporabljenim zamreževalnim reagentom). S pomočjo infrardeče spektroskopije in termogravimetrične analize so bili določeni najboljši pogoji zamreževanja, na podlagi katerih so bile reakcije zamreževanja celuloznega derivata prenesene na večjo skalo. Ugotovljeno je bilo, da so lastnosti hidrogelov odvisne od časa sušenja in koncentracije zamreževalnega reagenta. Hidrogel z najvišjo stopnjo absorpcije vode dobimo pri uporabi 10-odstotnega zamreževalnega reagenta. V tem primeru znaša stopnja absorpcije vode 54 %, kar je približno 10 % (m/m) več kot v primeru komercialnega hidrogela, ki je imel 45-odstotno stopnjo absorpcije vode. V drugem delu magistrskega dela sem študiral reakcije zamreževanja neposredno na nativni celulozni vlaknini. Primarno so bili pri reakcijah zamreževanja uporabljeni kislinski kloridi alifatskih karboksilnih kislin z različnimi dolžinami alifatskih verig (sukcinil, adipoil, suberoil in sebakoil diklorid). Na ta način je bil raziskan vpliv razdalje med posameznimi zamreženimi celuloznimi verigami na stopnjo absorpcije vode. Slednje je neposredno povezano tudi z velikostjo 3D-praznin, v katere se vežejo molekule vode. Reakcijski čas zamreževanja celuloze, temperatura zamreževanja in množinsko razmerje med celulozo in zamreževalnim reagentom so bili optimizirani. V nadaljevanju so bile reakcije zamreževanja izvedene tudi neposredno z dikarboksilnimi kislinami in ustreznimi anhidridi. Primerjal sem potek reakcij in lastnosti sintetiziranih hidrogelov pri uporabi različnih zamreževalnih reagentov. S pomočjo različnih analiznih tehnik je bil definiran optimalni zamreževalni reagent oziroma optimalni pogoji zamreževanja in reakcijo zamreževanja celulozne vlaknine sem prenesel na večje merilo. Rezultati so pokazali, da ima na lastnosti hidrogelov na osnovi celuloze največji vpliv množinsko razmerje med celulozo in uporabljenim zamreževalnim reagentom. V primeru nižjih količin zamreževalnih reagentov in posledično nižje stopnje zamreženja pride do izboljšanja absorpcijskih lastnosti napram absorpcijskim lastnostim celuloze. Zelo dobre absorpcijske lastnosti dosežemo v primeru, ko celulozo zamrežimo z nižjo množino zamreževalnega reagenta in jo nato še dodatno modificiramo s sukcinskim anhidridom. Delež vezane vode v tem primeru znaša okoli 44 % glede na maso suhega hidrogela, kar je primerljivo z lastnostmi komercialnega hidrogela. Najboljše absorpcijske lastnosti dosežemo v primeru modifikacije celuloze s sukcinsko kislino v mediju, sestavljenem iz N,N-dimetilacetamida in litijevega klorida. Pri omenjenem hidrogelu znaša stopnja absorpcije vode 70 %. The first part of my master's thesis investigates crosslinking syntheses of commercial carboxymethylcellulose sodium salt using different crosslinking reagents based on natural dicarboxylic acids of different chain length (citric acid, succinic acid, malic acid) and 2,5-furandicarboxylic acid as molecules from biomass. The crosslinking reactions were carried out under different conditions (reaction time and drying temperature as well as different molar ratios between the cellulose derivative and the crosslinking reagent). Infrared spectroscopy and thermogravimetric analysis were carried out to determine the best crosslinking conditions, and cellulose derivative crosslinking reactions were transferred to a larger scale. It was found that properties of hydrogels depended on drying time and concentration of the crosslinking reagent. The hydrogel with the highest water absorption rate is obtained when 10 wt % of the crosslinking reagent is used. In this case, the water absorption rate was 54%, which is approximately 10% more than that of the commercial hydrogel with a water absorption rate of 45%. In the second part of my master's thesis, crosslinking reactions directly on native cellulose fibers were studied. Primarily, acid chlorides of aliphatic carboxylic acids with different aliphatic chain lengths (succinyl-, adipoyl-, suberoyl- and sebacoyl-dichloride) were used to carry out the crosslinking reactions. In this way, the influence of the distance between individual cross-linked cellulose chains on the degree of water absorption was investigated. This is also directly related to the size of 3D spaces to which water molecules bind. The reaction time of cellulose crosslinking, the crosslinking temperature, and the ratio between cellulose and the crosslinking reagent were optimized. In addition, crosslinking reactions were also performed directly with dicarboxylic acids and anhydrides. Reactions and properties of the hydrogels synthesized using different crosslinking reagents were compared. Various analytical techniques were used to determine the optimal crosslinking reagent or optimal crosslinking conditions, and the crosslinking reaction of cellulose fibers was transferred to a larger scale. The results showed that the properties of cellulose-based hydrogels have the greatest influence on the mass ratio between cellulose and the crosslinking reagent used. With lower amounts of crosslinking reagents and consequently a lower degree of crosslinking, absorption properties, compared to those of cellulose, improve. The best absorption properties were achieved when cellulose was crosslinked with a lower amount of the crosslinking reagent and then additionally modified with succinic anhydride. In this case, the proportion of bound water was about 44%, based on the weight of the dry hydrogel, which is comparable to the properties of a commercial hydrogel. The best absorption properties are obtained when cellulose is modified with succinic acid in a medium comprising N,N-dimethylacetamide and lithium chloride. The hydrogel has a water absorption rate of 70%.

This study was carried out using bleached softwood Chemi-Thermo-Mechanical Pulp to evaluate the influence of Molded Pulp Products’ manufacturing process parameters on the finished products’ mechanical and hygroscopic properties. A Taguchi table was done to make 8 tests with specific process parameters such as moulds temperature, pulping time, drying time, and pressing time. The results of these tests were used to obtain an optimized manufacturing process with improved mechanical properties and a lower water uptake after sorption analysis and water immersion. The optimized process parameters allowed us to improve the Young’ Modulus after 30h immersion of 58% and a water uptake reduction of 78% with the first 8 tests done.

This work aims to reveal the effect of a high amount of cellulose fibers on the durability and protective behavior of a bio-based wood paint. The influence of the filler on the morphology of the coatings was investigated by scanning electron microscopy observations, while the durability of the paint was evaluated by exposing the samples to UV-B radiation and continuous thermal shocks. Infrared spectroscopy analysis, colorimetric inspections, adhesion tests and scanning electron microscope observations were employed to assess the role of the high concentrations of fillers in affecting the resilience of the acrylic matrix. Moreover, the impact of the filler on the barrier performance of the coatings was estimated using a liquid resistance test and a water uptake test. Finally, the mechanical properties of hardness and abrasion resistance of the layers were evaluated by means of the Buchholz Hardness Indentation test and the Scrub test. Ultimately, this study demonstrates the pros and cons of using large amounts of cellulose fibers as filler in wood paint: the work warns against the excessive use of these fibers, which need a threshold limit so as not to significantly change the coating’s structure and thereby weaken its protective properties.

Cellulose is classified as one of the most abundant biopolymers in nature. Its excellent properties have gained a lot of interest as an alternative material for synthetic polymers. Nowadays, cellulose can be processed into numerous derivative products, such as microcrystalline cellulose (MCC) and nanocrystalline cellulose (NCC). MCC and NCC have demonstrated outstanding mechanical properties owing to their high degree of crystallinity. One of the promising applications of MCC and NCC is high-performance paper. It can be utilized as a substitute for the aramid paper that has been commercially used as a honeycomb core material for sandwich-structured composites. In this study, MCC and NCC were prepared by extracting cellulose from the Cladophora algae resource. MCC and NCC possessed different characteristics because of their distinct morphologies. Furthermore, MCC and NCC were formed into a paper at various grammages and then impregnated with epoxy resin. The effect of paper grammage and epoxy resin impregnation on the mechanical properties of both materials was studied. Then, MCC and NCC paper was prepared as a raw material for honeycomb core applications. The results showed that epoxy-impregnated MCC paper outperformed epoxy-impregnated NCC paper with a compression strength of 0.72 MPa. The interesting result from this study is that the compression strength of the MCC-based honeycomb core was comparable to the commercial ones despite being made of a natural resource, which is sustainable and renewable. Therefore, cellulose-based paper is promising to be used for honeycomb core applications in sandwich-structured composites.

The triboelectric nanogenerator (TENG) is a newly developed energy harvesting technology that can convert mechanical energy into electricity. The TENG has received extensive attention due to its potential applications in diverse fields. In this work, a natural based triboelectric material has been developed from a natural rubber (NR) filled with cellulose fiber (CF) and Ag nanoparticles. Ag nanoparticles are incorporated into cellulose fiber (CF@Ag) and are used as a hybrid filler material for the NR composite to enhance the energy conversion efficiency of TENG. The presence of Ag nanoparticles in the NR-CF@Ag composite is found to improve the electrical power output of the TENG by promoting the electron donating ability of the cellulose filler, resulting in the higher positive tribo-polarity of NR. The NR-CF@Ag TENG shows significant improvement in the output power up to five folds compared to the pristine NR TENG. The findings of this work show a great potential for the development of a biodegradable and sustainable power source by converting mechanical energy into electricity.

The current trends in micro-/nanofibers offer a new and unmissable chance for the recovery of cellulose from non-woody crops. This work assesses a technically feasible approach for the production of micro- and nanofibrillated cellulose (MNFC) from jute, sisal and hemp, involving refining and enzymatic hydrolysis as pretreatments. Regarding the latter, only slight enhancements of nanofibrillation, transparency and specific surface area were recorded when increasing the dose of endoglucanases from 80 to 240 mg/kg. This supports the idea that highly ordered cellulose structures near the fiber wall are resistant to hydrolysis and hinder the diffusion of glucanases. Mechanical MNFC displayed the highest aspect ratio, up to 228 for hemp. Increasing the number of homogenization cycles increased the apparent viscosity in most cases, up to 0.14 Pa·s at 100 s−1 (1 wt.% consistency). A shear-thinning behavior, more marked for MNFC from jute and sisal, was evidenced in all cases. We conclude that, since both the raw material and the pretreatment play a major role, the unique characteristics of non-woody MNFC, either mechanical or enzymatically pretreated (low dose), make it worth considering for large-scale processes Authors wish to acknowledge the financial support of the Spanish Ministry of Economy and Competitiveness to the project NANOPROSOST (CTQ2017-85654-C2-1-R and CTQ2017-85654-C2-2-R)

Different wetland plants were evaluated regarding their potential to be used in further green biorefining platforms to produce soluble protein and cellulose-textile fibers. The results show a higher protein content in the plants grown in treatment wetland conditions, compared with the same species grown in natural conditions, and diverse effect on the content of cellulose, hemicellulose, and lignin, depending on the plant species, more than the growing environment. The TW biomass did not represent a risk regarding accumulation of heavy metals, named Pb, Cd, and Cr, since the studied plants did not present it in their tissues, neither in the roots nor in the leaves. The results regarding cellulose quality of the TW plants showed positive results, having values of molar mass distributions and degrees of polymerization that suggest a suitability to be considered for cellulose-fiber textiles studies. This is one of the first approaches, in the TW field, to establish a new criterion for selecting plant species to be planted in the system, aiming at recovering resources and use them as inputs for biorefineries and sustainable biobased products.

The article presents a method of obtaining films based on carboxymethyl polysaccharide derivatives cross-linked with citric acid and reinforced with cellulose fibers (CFs). The addition of CFs to a film improves the mechanical properties of the composite. With the increase of filler content, the water solubility drops from 64 to 61%, respectively, for a system without a filler and that containing 7 wt% CFs, whereas Young’s modulus increases from 4.8 to 24.8 MPa for a film containing 5 wt% filler.

It is very difficult to directly spin the lignocellulose without pretreatment. Ionic liquids (ILs) are promising solvent to dissolve lignocellulose to prepare cellulose fiber. However, the degree of cellulose polymerization（DP）is reduced when lignocellulose is dissolved in ILs, and the lignin removal rate is low. The elongation at break and tensile strength of the fibers obtained by spinning the lignocellulose dissolved in ILs are poor. In this paper, preparing cellulose fiber directly from lignocellulose based on dissolving corn stalk via [C4mim]Cl-L-arginine binary system is achieved. It shows that the removal rate of lignin can reach 92.35% and the purity of cellulose can reach 85.32% after corn stalk was dissolved at 150 °C for 11.5 h when the mass fraction of arginine is 2.5%. The elongation at break of fiber reached 10.12% and the tensile strength reached 420 MPa. It is mainly due to the fact that L-arginine not only inhibits the degradation of cellulose but also promotes the delignination. Without any pulping or pretreatment, preparing cellulose fibers via direct dissolution and extrusion may provide a simple and effective way to prepare many novel cellulose materials.

Based on publications related to the use of micro- and nanofibrillated cellulose (MNFC) in papermaking applications, three sets of parameters (intrinsic and extrinsic variables, furnish composition, and degree of dispersion) were proposed. This holistic approach intends to facilitate understanding and manipulation of the main factors describing the colloidal behavior in systems comprising of MNFC, pulp fibers, and additives, which directly impact paper product performance. A preliminary techno-economic assessment showed that cost reductions driven by the addition of MNFC in paper furnishes could be as high as USD 149 per ton of fiber (up to 20% fiber reduction without adverse effects on paper’s strength) depending on the cost of papermaking fibers. It was also determined that better performance in terms of strength development associated with a higher degree of MNFC fibrillation offset its high manufacturing cost. However, there is a limit from which additional fibrillation does not seem to contribute to further strength gains that can justify the increasing production cost. Further research is needed regarding raw materials, degree of fibrillation, and combination with polyelectrolytes to further explore the potential of MNFC for the reduction of weight of paper products.

As one of the hazardous heavy metal ion pollutants, Cr(VI) has attracted much attention in the sewage treatment research field due to its wide distribution range and serious toxicity. In this paper, cellulose fibers were prepared by wet spinning and followed by freeze drying, resulting in large porosity. Subsequently, in-depth sulfhydryl modification was applied with cellulose fibers for efficient and rapid adsorption of Cr(VI). The maximum adsorption capacity of sulfhydryl-modified cellulose fibers to Cr(VI) can reach 120.60 mg g−1, the adsorption equilibrium can be achieved within 300 s, and its adsorption rate can reach 0.319 mg g−1 s−1. The results show that the in-depth sulfhydryl-modified cellulose fibers perform excellent adsorption capacity for chromium, and are also available for other heavy metal ions. At the same time, the low cost and environmentally friendly property of the as-synthesized material also demonstrate its potential for practical usage for the treatment of heavy metal ion pollution in waste water.

The purpose of this work is to obtain dissolving cellulose fibers that are suitable for the manufacturing of cellulose derivatives. Therefore, the combination of enzymatic and chemical treatments during the bleaching stage (lignin removal) and purification stage (hemicellulose removal) is proposed. The obtained dissolving cellulose was submitted to acetylation reactions, and then acetate films were prepared as an example of end product. Assessing the quality of acetate films, it was concluded that dissolving cellulose fibers had good properties and fulfilled the quality requirements. These satisfactory results were compared with acetate films obtained under same acetylation conditions, but the dissolving cellulose fibers used as a raw material came from a conventional and industrial process. This publication is part of the PID2020-114070RB-I00 (CELLECOPROD) project, funded by MCIN/AEI/10.13039/501100011033. O.J.R. acknowledges funding support by the Academy of Finland through its Center of Excellence Program (2014–2019) “Molecular Engineering of Biosynthetic Hybrid Materials Research”.

The use of micro-/nanofibrillated celluloses (M/NFCs) is often considered for the enhancement of paper properties, while it is still challenging to use them in lower weight gain coatings. This work explores how they might be used on the paper surface to improve the printing quality. In this regard, M/NFCs were produced using different pre-treatment methods, including mechanical (m-MFC), enzymatic (e-MFC), TEMPO-mediated oxidation (t-NFC) and cationization (c-NFC), and uniform coating formulations were developed through the cooking of starch and M/NFCs simultaneously. The formulations, at 6–8% of total solid concentration, were applied to the paper surface by roll coating, resulting in a dry coating weight of 1.5 to 3 g/m2. Besides M/NFCs, other components such as starch betainate (a cationic starch ester; SB), Pluronics® (a triblock co-polymer), precipitated calcium carbonate (PCC) and betaine hydrochloride (BetHCl) were also used in the M/NFC-based coating formulations to observe their combined influence on the printing quality. The presence of M/NFCs improved the paper printing quality, which was further enhanced by the increase in cationic charge density due to the presence of BetHCl/SB, and also by Pluronics®. The cationic charge of c-NFC was also found to be effective for improving the gamut area and optical density of coated papers, whereas whiteness was often reduced due to the quenching of the brightening agent. BetHCl, on the other hand, improved the printing quality of the coated papers, even though it was more effective when combined with M/NFCs, PCC and Pluronics®, and also helped to retain paper whiteness This work was carried out under the Project inpactus -innovative products and technologies from eucalyptus, Project N.º 21874 funded by Portugal 2020 through European Regional Development Fund (ERDF) in the frame of COMPETE 2020 nº246/AXIS II/2017. Authors would like to thank the Coimbra Chemical Centre, which is supported by the Fundação para a Ciência e a Tecnologia (FCT), through the projects UID/QUI/00313/2020 and COMPETE. Authors would also like to thank the CIEPQPF-Strategic Research Centre Project UIDB/00102/2020, funded by the Fundação para a Ciência e Tecnologia (FCT). M.S. acknowledges the PhD grant BDE 03|POCI-01-0247-FEDER-021874. R.A. acknowledges the post-doc grant BPD 02|POCI-01-0247-FEDER-021874

U svijetu danas suočavamo se sa dosta ekoloških problema, pogotovo sa zagađenjem atmosfere i planeta. Nemamo adekvatne sustave za zbrinjavanje otpada zato što ne postoje. Znanstvenici danas provode sve više istraživanja oko prirodnih polimera zbog biorazgradnje i njenog djelovanja sa kemijskim vezama u polimerima. Nakon korištenja stvari koje se ne mogu biorazgraditi, odbacuju se na odlagališta otpada ili idu na termičku obradu otpada. Ti načini zbrinjavanja otpada su opasni i štetni za čovjeka i za okoliš. Biorazgradnja danas dobiva bitnu svrhu jer materijale pretvara u vodu, ugljični dioksid i biomasu što znači da ne onečišćujemo okoliš. U ovom diplomskom radu provedeno je istraživanje o utjecaju atmosferilija na biorazgradivost celuloznih vlakana. Ovo istraživanje također pomaže u stjecanje uvida u vremenski vijek trajanja raznih celuloznih vlakana (pamuk, lan, juta) i viskozna vlakna. Zadatak rada je ispitati utjecaj atmosferilija na biorazgradivost celuloznih vlakana. U tu svrhu odabrale su se tekstilije pamučnih, lanenih i jutenih vlakana te viskoznih vlakana kao predstavnik celuloznih regenerata. Uzorci su bili podvrgnuti biorazgradivosti u stvarnim uvjetima u vremenskom razdoblju od 10, 15, 20 i 25 dana. Utjecaj prirodnih klimatskih uvjeta, odnosno utjecaj atmosferilija na biorazgradivost ocjenjivana je mjerenjem i međusobnim uspoređivanjem promjena vlačnih svojstava, promjena plošne mase i debljine uzoraka te analizom morfologije tekstilija., In the world today, we face many environmental problems, especially the pollution of the atmosphere and the planets. We do not have adequate waste management systems because they do not exist. Scientists today are conducting more and more research around natural polymers due to biodegradation and its action with chemical bonds in polymers. After using things that cannot be biodegradable, they are disposed of in landfills or go to the thermal treatment of waste. These methods of waste disposal are dangerous and harmful to humans and the environment. Biodegradation today has an important purpose because it converts materials into water, carbon dioxide and biomass, which means that we do not pollute the environment. In this thesis, a study was conducted on the influence of atmospherics on the biodegradability of cellulose fibers. This research also helps to gain insight into the lifetime of various cellulose fibers (cotton, linen, jute) and viscose fibers. The task of this paper is to examine the influence of atmospherics on the biodegradability of cellulose fibers. For this purpose, textiles of cotton, flax and jute fibers and viscose fibers were chosen as a representative of cellulose regenerates. The samples were subjected to biodegradability under real conditions for a period of 10, 15, 20 and 25 days. The influence of natural climatic conditions, is the influence of atmospherics on biodegradability was assessed by measuring and comparing changes in tensile properties, changes in surface mass and thickness of samples and analysis of textile morphology.

The aim of this study was to investigate a possibility of synthesis of porous ceramics with controlled open porosity, which could be used as sorbents and catalyst supports. Two organic additives were used to obtain open porosity: polystyrene beads and cellulose fibers, which are mixed with kaolin clay powder and the appropriate water content. Samples were sintered at 1050 oC for 1 h. Characterization of the obtained products included X-ray powder diffraction analysis (XRPD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and elemental CHNS analysis. In addition, porosity was examined by quantification of visual information. The specific surface areas were determined by the Brunauer–Emmett–Teller (BET) method. Also, density and compressive strength of the obtained samples were assessed. It was determined that by sintering, the organic component completely leaves the system. For samples prepared with polystyrene beads and with cellulose fibers, satisfactory mechanical properties were obtained: compressive strengths were 1.42 and 1.56 MPa, respectively. It was noted that significantly higher open porosity was obtained by using polystyrene beads as a sacrificial template (porosity of ~56 %) instead of cellulose fibers (porosity of ~6 %).

To test the acoustic performance of fiber-reinforced composites for replacing wood, an acoustic vibration test method is developed. For evaluation of the test method, composites are manufactured using hemp and ramie embedded in epoxy, through vacuum-assisted resin infusion molding. The effects of the most important factors, i.e., impulse, relative humidity (RH), and specimen thickness, on the acoustic vibration response of the composites are systematically studied. The magnitudes of the impulses, represented by different masses of the dropping balls, seem to have little influence on the shapes of the acoustic vibration curves, although the intensity of the spectra increases as the impulse increases. The RH influences the spectrum shape significantly due to variation in the Young’s modulus and density of the material upon absorption of moisture. The specimen thickness also greatly affects the testing results. The specific dynamic modulus, acoustic radiation damping coefficient, and acoustic impedance change a little as the impulse magnitude and RH change, but decrease substantially as the specimen thickness increases. The specific dynamic modulus can be linearly correlated with the flexural modulus of a material.

This research aimed to study the influence of lyocell with incorporated ZnO (CLY) for antibacterial activity and biodegradation of fiber blends composed of viscose (CV), flax (LI), and CLY. Fiber blended samples with an increased weight fraction of CLY fibers were composed, and single CLY, CV and LI fibers were also used for comparison. Antibacterial activity was determined for the Gram-negative Escherichia coli and the Gram-positive Staphylococcus aureus bacteria. The biodegradation of fiber blends was investigated by the soil burial test. The results show that the single CLY fibers exhibited high antimicrobial activity against both E. coli and S. aureus bacteria and that the presence of LI fibers in the blended samples did not significantly affect antibacterial activity against E. coli, but drastically decreased the antibacterial activity against S. aureus. LI fibers strongly promoted the growth of S. aureus and, consequently, impaired the antimicrobial performance of ZnO against this bacterium. The presence of CLY fibers slowed down, but did not prevent, the biodegradation process of the fiber blends, even at the highest ZnO concentration. The soil that was in contact with the fiber blended samples during their burial was not contaminated to such an extent as to affect the growth of sprouts, confirming the sustainability of the fiber blends.

Tissue paper production frequently combines two main types of raw materials: cellulose fibers from renewable sources and polymer-based additives. The development of premium products with improved properties and functionalities depends on the optimization of both. This work focused on the combination of innovative experimental and computational strategies to optimize furnish. The main goal was to improve the functional properties of the most suitable raw materials for tissue materials and develop new differentiating products with innovative features. The experimental plan included as inputs different fiber mixtures, micro/nano fibrillated cellulose, and biopolymer additives, and enzymatic and mechanical process operations. We present an innovative tissue paper simulator, the SimTissue, that we have developed, to establish the correlations between the tissue paper process inputs and the end-use paper properties. Case studies with industrial interest are presented in which the tissue simulator was used to design tissue paper materials with different fiber mixtures, fiber modification treatments, micro/nano fibrillated cellulose, and biopolymer formulations, and to estimate tissue softness, strength, and absorption properties. The SimTissue was able to predict and optimize a broader range of formulations containing micro/nanocellulose fibers, biopolymer additives, and treated-fiber mixtures, saving laboratory and industrial resources.

Miscanthus x giganteus je visokoučinkovita energetska kultura koja nalazi svoju primjenu u raznim poljima, prvenstveno za biogorivo, ali se sukladno rezultatima istraživanja prikazanog u ovom radu, može primijeniti i za tehničke tekstilije npr. filtere ili kao ojačalo u proizvodnji kompozitnih materijala. Zbog visoke produktivnosti i neinvazivnosti, te otpornosti na različite klime, Miscanthus postaje važna sirovina za petrokemijsku, građevinsku, papirnu i tekstilnu industriju. S obzirom da energetske biljke, dobivaju sve veći značaj, kako u agronomiji tako i tekstilnoj industriji iz razloga održivog razvoja i ekonomičnosti postupaka proizvodnje je upravo ova kultura odabrana za temu završnog rada. Cilj rada bio je izdvojiti celulozna vlakna iz stabljike biljke Miscanthus x giganteus na ekonomičan i ekološki povoljan način. U radu je prikazana mogućnost primjene različitih postupaka obrade, koji su podijeljeni u preliminarne i završne. Preliminarnim istraživanjima je utvrđeno da optimalni postupak uključuje oksidativnu obradu primjenom vodikovog peroksida i primjenom mikrovalne tehnologije. U završnom postupku je odabrana metoda unaprijeđena određivanjem optimalnih omjera kupelji i vremena obrade primjenom mikrovalnog zračenja. Za morfološku karakterizaciju izdvojenih vlakana su primijenjeni svjetlosni mikroskop Dino-Lite i skenirajući elektronski mikroskop (SEM) kojima je utvrđena dužina i izgled vlakana. Dobiveni rezultati su potvrdili potencijal Miscanthusa kao ekološke i održive sirovine iz koje je moguće izdvojiti celulozna vlakna koja bi svoju primjenu mogla naći u raznim područjima industrije i tehnologije., Miscanthus x giganteus is a highly efficient energy crop that finds its application in various fields, primarily for biofuels. According to this research, it can be applied for technical textiles such as filters or as a reinforcement in the production of composite materials as well. Due to its high productivity, non-invasiveness, and resistance to different climates, Miscanthus becomes an important raw material for the petrochemical, construction, paper, and textile industries. Energy crops are becoming increasingly important, both in agronomy and the textile industry due to its sustainability and cost-effectiveness of production processes. For that reason is Miscanthus x giganteus, as one of the representatives of energy crops, chosen for the topic of this thesis. The aim of this work was to extract fibers from the Miscanthus giganteus stem in an economic and ecologically accepted way. The thesis presents the possibility of different processing treatments application, which are divided into preliminary and final. Preliminary research determined oxidative treatment with hydrogen peroxide and microwave technology as the best. In final procedure, chosen method was optimized by finding the optimal bath ratios and microwave treatment duration. For the morphological characterization of the isolated fibers, Dino-Lite and the FE-SEM (Field Emission Scanning Electron Microscope) were used to determine fiber length and appearance. The obtained results confirmed the potential of Miscanthus x giganteus as an ecological and sustainable source of cellulose fibers that can be applicable in various fields of industry and technology.

A agência norte-americana de práticas ambientais (EPA, 2009), dentro da proposta de práticas sustentáveis, sugere a substituição de revestimentos impermeáveis por outros como o de concreto asfáltico permeável. O uso desse revestimento permite redução do acúmulo de água, aumento da aderência, maior segurança de tráfego em condições de pista molhada e redução de ruídos relacionados ao rolamento. O presente trabalho visou estudar a influência da adição de quatro diferentes teores de fibra de celulose em uma mistura de concreto asfáltico permeável com ligante modificado por polímeros. Utilizaram-se agregados da faixa I de granulometria da norma de Camada Porosa de Atrito (DNER-ES 386/99). O teor de ligante de projeto foi de 4%, correspondente a 18,3% de vazios. Com a utilização de 0%, 0,25%, 0,50% e 0,75% de fibras, analisaram-se cinco parâmetros: coeficiente de permeabilidade (adaptação do método prescrito na norma ACI 522R – 06); teor de vazios comunicantes (AFNOR-NF-P-98-254-2 - 1993); perda ao cântabro (DNERME 383/99); resistência à tração por compressão diametral (DNIT 136/2018 – ME) e módulo de resiliência (DNIT 135/2018-ME). Na ausência de uma norma que regulamente o processo de medição do coeficiente de permeabilidade, criou-se um equipamento capaz de ensaiar CPs compactados segundo a DNER-ES 386/99. O aparato, inspirado em uma norma norte-americana, mostrou-se bastante eficiente; de forma a constituir uma possibilidade de complemento da norma de camada porosa de atrito. Os parâmetros nos quais a porcentagem de fibra exerceu influência significativa foram Módulo de Resiliência (MR) e Coeficiente de Permeabilidade (k). O valor de MR foi máximo quando o teor de fibras foi de 0,25%, semelhante ao obtido para o grupo com 0% e significativamente distinto dos grupos com 0,50% e 0,75% O valor de k foi significativamente distinto para cada grupo, mostrando um aumento até a adição de fibras em 0,50%. O grupo com 0,50% de fibras apresentou o maior valor de k e MR 32% inferior ao grupo com 0,25%. Quando comparado aos grupos sem fibra e com teor de 0,75%, o grupo com 0,25% apresentou os maiores valores de MR e k. The American Environmental Practices Agency (EPA, 2009), within the proposal of sustainable practices, suggests the replacement of waterproof coatings for others such as permeable asphalt concrete. The use of this coating allows reduction on water accumulation, increased grip, increased traffic safety in wet road conditions and reduced rolling noise. The present work aimed to study the influence of the addition of four different contents of cellulose fiber in a mix of permeable asphalt concrete with polymer modified binder. Aggregates of the particle size range I of the Porous Friction Layer standard (DNER-ES 386/99) were used. The design binder content was 4%, corresponding to 18.3% voids. Using 0%, 0.25%, 0.50% and 0.75% of fibers, five parameters were analyzed: permeability coefficient (adaptation of the method prescribed in the ACI 522R – 06); content of communicating voids (AFNOR-NF-P-98-254-2 - 1993); loss to cantabrian (DNER-ME 383/99); tensile strength by diametrical compression (DNIT 136/2018 - ME) and resilience modulus (DNIT 135/2018-ME). In the absence of a standard that regulates the permeability coefficient measurement process, an equipment capable of testing compacted CPs according to DNER-ES 386/99 was created. The apparatus, inspired by an american standard, proved to be efficient; the methodology constitutes a possibility of complement of the porous friction layer standard. The parameters on which the fiber percentage exerted a significant influence were Resilience Modulus (MR) and Permeability Coefficient (k). The MR value was maximum when the fiber content was 0.25%, similar to the obtained for the 0% group and significantly different from the 0.50% and 0.75% groups. The k value was significantly different for each group, showing an increase up to the addition of fibers by 0.50%. The group with 0.50% fiber had the highest value of k and MR 32% lower than the group with 0.25%. When compared to the groups without fiber and with a content of 0.75%, the group with 0.25% presented the highest values of MR and k.

Green composites, composed of bio-based matrices and natural fibers, are a sustainable alternative for composites based on conventional thermoplastics and glass fibers. In this work, micronized bleached Eucalyptus kraft pulp (BEKP) fibers were used as reinforcement in biopolymeric matrices, namely poly(lactic acid) (PLA) and poly(hydroxybutyrate) (PHB). The influence of the load and aspect ratio of the mechanically treated microfibers on the morphology, water uptake, melt flowability, and mechanical and thermal properties of the green composites were investigated. Increasing fiber loads raised the tensile and flexural moduli as well as the tensile strength of the composites, while decreasing their elongation at the break and melt flow rate. The reduced aspect ratio of the micronized fibers (in the range from 11.0 to 28.9) improved their embedment in the matrices, particularly for PHB, leading to superior mechanical performance and lower water uptake when compared with the composites with non-micronized pulp fibers. The overall results show that micronization is a simple and sustainable alternative for conventional chemical treatments in the manufacturing of entirely bio-based composites.

This paper reports the influence of submicron hydrophilic fibers on the hydration and microstructure of Portland cement paste. Submicron fibrillated cellulose (SMC) fibers was prepared by the acid hydrolysis of cotton fibers in H2SO4 solution (55% v/v) for 1.5 h at a temperature of 50 °C. The SMC fibers were added into cement with a dosage of 0.03 wt.%, and the effect of SMC on the hydration and microstructure of cement paste was investigated by calorimeter analysis, XRD, FT-IR, DSC-TG, and SEM. Microcrystalline cellulose (MCC) fibers were used as the contrast admixture with the same dosage in this study. The results show that the addition of SMC fibers can accelerate the cement hydration rate during the first 20 h of the hydration process and improve the hydration process of cement paste in later stages. These results are because the scale of SMC fibers more closely matches the size of the C-S-H gel compared to MCC fibers, given that the primary role of the SMC is to provide potential heterogeneous nucleation sites for the hydration products, which is conducive to an accelerated and continuous hydration reaction. Furthermore, the induction and bridging effects of the SMC fibers make the cement paste microstructure more homogeneous and compact.

The present paper proposes a novel approach for the morphological characterization of cellulose nano and microfibers suspensions (CMF/CNFs) based on the analysis of eroded CMF/CNF microscopy images. This approach offers a detailed morphological characterization and quantifi-cation of the micro and nanofibers networks present in the product, which allows the mode of fibrillation associated to the different CMF/CNF extraction conditions to be discerned. This information is needed to control CMF/CNF quality during industrial production. Five cellulose raw materials, from wood and non-wood sources, were subjected to mechanical, enzymatic, and (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl (TEMPO)-mediated oxidative pre-treatments followed by different homogenization sequences to obtain products of different morphologies. Skeleton analysis of microscopy images provided in-depth morphological information of CMF/CNFs that, complemented with aspect ratio information, estimated from gel point data, allowed the quantification of: (i) fibers peeling after mechanical pretreatment; (ii) fibers shortening induced by enzymes, and (iii) CMF/CNF entanglement from TEMPO-mediated oxidation. Being mostly based on optical microscopy and image analysis, the present method is easy to implement at industrial scale as a tool to monitor and control CMF/CNF quality and homogeneity. This research was funded by the Spanish Ministry of Economy and Competitiveness for the funding of the projects CTQ2017-85654-C2-1-R and CTQ2017-85654-C2-2-R and the Community of Madrid via funding of RETO-PROSOST-2-CM (S2018/EMT4459), as well as the Universidad Complutense de Madrid and Banco de Santander via the grant of J.L. Sanchez-Salvador (CT17/17). Thanks also go to the Spanish Ministry of Science and Innovation for the Juan de la Cierva aid of Cristina Campano (Ref. FJC2019-040298-I). Marc Delgado-Aguilar is a Serra Húnter Fellow.

Cellulose nanofiber (CNF) as a bio-based reinforcement has attracted tremendous interests in engineering polymer composites. This study developed a sustainable approach to reinforce polyamide-6 or nylon-6 (PA6) with CNFs through solvent casting in formic acid/water mixtures. The methodology provides an energy-efficient pathway towards well-dispersed high-CNF content PA6 biocomposites. Nanocomposite formulations up to 50 wt.% of CNFs were prepared, and excellent improvements in the tensile properties were observed, with an increase in the elastic modulus from 1.5 to 4.2 GPa, and in the tensile strength from 46.3 to 124 MPa. The experimental tensile values were compared with the analytical values obtained by micromechanical models. Fractured surfaces were observed using scanning electron microscopy to examine the interface morphology. FTIR revealed strong hydrogen bonding at the interface, and the thermal parameters were determined using TGA and DSC, where the nanocomposites’ crystallinity tended to reduce with the increase in the CNF content. In addition, nanocomposites showed good thermomechanical stability for all formulations. Overall, this work provides a facile fabrication pathway for high-CNF content nanocomposites of PA6 for high-performance and advanced material applications This research was funded by the Biocomposites Program within the Knut and Alice Wallenberg Foundation (Sweden), a UdG grant (IFUdG 2017), Spain, and a three-month research grant from KTH (C2019-1106), Sweden. Support from the Spanish Ministry of Science, Innovation and Universities (RTI 2018-102070-B-C22) is also acknowledged

Development of cationic flocculants from lignocellulosic wastes not only eliminates the health and environmental concerns associated with the use of conventional chemicals but also is the way of waste valorization. In the present study, cellulose fibers extracted from rice husk were cationized through an optimization method based on Response Surface Methodology. The fibers cationized at the optimal conditions had a zeta potential of 15.2±1.0 mV, which was 1.73-fold higher than that of the preliminary experiments. FTIR analysis proved the presence of the corresponding functional groups. The functionalized fibers were biodegradable and had absolutely positive surface charges at a broad pH range. The cationized fibers were employed as a flocculant to remove turbidity from the synthetic wastewaters at various pHs and initial turbidities. The cationic fibers showed the excellent turbidity removals up to 98.5% from the synthetic wastewater without the need for conventional coagulants. In contrast to traditionally cationized fibers, the synthesized flocculants did not affect the effluent color during coagulation-flocculation. The charge neutralization and bridging through adsorption were the governing mechanisms of flocculation. The procedure can be applied on lignocellulosic wastes to develop cationic fibers with the excellent flocculation ability and suitable operational characteristics.

In this study, the natural dye was extracted from Spartium junceum L. (SJL) flowers and applied on cellulose (cotton) and protein (wool) fabric. Fabrics were pre-mordant with alum prior to the dyeing process. Considering the global requirements on zero waste and green policy, the dyeing process was intended to be as much as possible environmentally friendly but still effective. Therefore, mordant concentration was optimized due to the reduction of the negative impact. The efficiency of the dyeing process was investigated by examination of fabrics’ color characteristics and colorfastness to washing properties. In this paper, we have proved that the extracted dye from Spartium junceum L. is an acidic dye (mordant dye) which is more applicable for the treatment of wool fabrics. In this paper, it was proved that phytochemicals responsible for coloring are part of the flavonoids group. The UV absorption spectra of extracted dye show 4 bands in the region of λmax 224, 268, 308 and 346 nm which are ascribed to bands characteristic for flavonoids. Wool fabric pre-mordant with 3% alum and dyed shows great chromatic (C*) properties where C* value is in a range from 47.76 for unwashed samples to 47.50 for samples after 5 washing cycles and color hue (h°) is in a range 82.13 for unwashed samples to 81.52 for samples after 5 washing cycles. The best result regarding the colorfastness properties is shown by the wool sample treated with 3% alum after 5 washing cycles (total difference in color (Delta E*) = 0.87). These results confirm that metal (Al) from alum mordant make strong chemical bonds with wool substrate and dye since Delta E* values decrease in comparison to Delta E* values of the cotton samples treated the same way. The results revealed it is possible to reduce the concentration of mordant up to 3% and obtain satisfactory results regarding the colorfastness. Nevertheless, future research will go in the direction of replacing synthetic mordant with a more environmentally friendly one.

Aiming for a cost-effective and environmentally friendly material, we propose the replacement of glass fiber/poly(acrylonitrile-co-butadiene-co-styrene) (ABS) composites by composites with cellulosic reinforcing agents. Industrial production of these composites is hindered by high cost and/or fiber surface modification methods. We report that 30% in weight (wt. %) of pristine cellulose fibers (CF) are highly adherent to an ABS matrix, as verified by microscopy. This provides an overall enhancement of 20% in tensile and flexural mechanical properties. Fiber/matrix adhesion derives from the oxidation of polybutadiene (PB) segments during extrusion, which generates epoxide groups that react with hydroxyls from CF to form ether bonds. We used additives for testing improvement of fiber/matrix adhesion. The addition of XIBOND™ 160 (maleic anhydride grafted polystyrene) reduces fiber/matrix adhesion due to the competition between the grafting of cellulose fibers onto PS segments of the additive and PB domains of ABS. Lignin catalyzes the epoxide reaction with hydroxyls, which leads to improvements in flexural mechanical properties. Overall, ca. 20 wt. % of ABS can be effectively saved by adding 30 wt. % of CF, with improvement of mechanical properties. The density of the composites is 1.3 g cm−3, similar to glass fiber/ABS composite densities. Therefore, CF is effective as a reinforcing filler for ABS, reducing cost and improving mechanical properties.

Thorough characterization and fundamental understanding of cellulose fibers can help us develop new, sustainable material streams and advanced functional materials. As an emerging nanomaterial, cellulose nanofibrils (CNFs) have high specific surface area and good mechanical properties; however, handling and processing challenges have limited their widespread use. This work reports an in-depth characterization of self-fibrillating cellulose fibers (SFFs) and their use in smart, responsive filters capable of regulating flow and retaining nanoscale particles. By combining direct and indirect characterization methods with polyelectrolyte swelling theories, it was shown that introduction of charges and decreased supramolecular order in the fiber wall were responsible for the exceptional swelling and nanofibrillation of SFFs. Different microscopy techniques were used to visualize the swelling of SFFs before, during, and after nanofibrillation. Through filtration and pH adjustment, smart filters prepared via in situ nanofibrillation showed an ability to regulate the flow rate through the filter and a capacity of retaining 95% of 300 nm (diameter) silica nanoparticles. This exceptionally rapid and efficient approach for making smart filters directly addresses the challenges associated with dewatering of CNFs and bridges the gap between science and technology, making the widespread use of CNFs in high-performance materials a not-so-distant reality. QC 20220406

The degree of molecular contact, i.e. the contact area on the nanometer scale, between paper fibers is crucial for the van-der-Waals and hydrogen bond adhesion between the fibers and thus for the fiber-fiber bond strength. We apply Förster resonance energy transfer (FRET) to investigate the degree of contact in the distance range of 1–10 nm between pulp fiber bonds and between thin films. The FRET system with DCCH and FTSC as fluorescence dyes has been validated for spectrophotometry and for local imaging with widefield microscopy, using pHema thin films. Bonding between thin films can be detected with this system, however it has not been possible to achieve a significant FRET signal between bonded pulp fibers. Therefore, we conclude that in principle it is possible to quantify the degree of contact between two surfaces on the nanometer scale with the investigated FRET system. For further work on pulp fibers we recommend an exclusively surface active dyeing, as bulk dyeing massively deteriorates the signal to noise ratio which is likely the reason for the low FRET signal found in this work.

On an industrial scale, it is a challenge to achieve cellulose based nanocomposites due to dispersion issues and high process temperatures sensitivity. The current study describes methods to develop mechanically strong and thermally stable polyamide 6 (PA 6) and cellulose nanofibers (CNF) composites capable of tolerating high processing temperatures. With PA 6 being a very technical polymer matrix to be reinforced with CNF, good dispersion can be achieved with a high speed kinetic mixer and also shield the CNF from excess thermal degradation by implementing extremely short processing time. This paper presents an industrially feasible method to produce PA 6/CNF nanocomposites with high CNF composition processed by a high speed kinetic mixer (GELIMAT®) followed by compression molding to obtain a homogenous and thermally stable nanocomposites aimed at high performance applications. PA 6 was reinforced with three different wt % formulations (5, 15 and 25 wt %) of cellulose nanofibers. The resulting nanocomposites exhibited significant increase in Young’s modulus and ultimate strength with CNF content, owing to the effective melt processing and the surface charge density of the CNF, which necessitated the dispersion. The thermal stability and polymer crystallinity with respect to CNF composition for the PA 6/CNF nanocomposites were examined by TGA and DSC analysis. Rheology studies indicated that viscosity of the composites increased with increase in CNF composition. Overall, this work demonstrates industrially viable manufacturing processes to fabricate high performance PA 6/CNF nanocomposites This research was funded by the Wallenberg Wood Science Institute—KTH (KAW 2018.0451, Sweden) in Sweden, the by UdG grant (IFUdG 2017) in Spain, and by the Spanish Ministry of Science, Innovation and Universities (RTI 2018-102070-B-C22)

The purpose of this work is to obtain dissolving cellulose fibers that are suitable for the manufacturing of cellulose derivatives. Therefore, the combination of enzymatic and chemical treatments during the bleaching stage (lignin removal) and purification stage (hemicellulose removal) is proposed. The obtained dissolving cellulose was submitted to acetylation reactions, and then acetate films were prepared as an example of end product. Assessing the quality of acetate films, it was concluded that dissolving cellulose fibers had excellent properties and fulfilled the quality requirements. These satisfactory results were compared with acetate films obtained under same acetylation conditions, but the dissolving cellulose fibers used as a raw material came from a conventional and industrial process

L’actual creixement de la demanda de nanocel·lulosa al mercat, com a conseqüència de les seves excel·lents propietats fisico-mecàniques, fa imperatiu el desenvolupament de les tecnologies de producció de nanofibres de cel·lulosa (CNF) a gran escala que permetin reduir costos de producció i tenir informació en temps real del procés. La nanocel·lulosa proporciona l’oportunitat de reinventar els materials en diferents sectors, al mateix temps que proposa molts reptes en la caracterització, disseny, processat i escalat. Per a la producció de CNF, generalment se segueixen dues etapes consecutives: (i) els pretractaments, que poden ser mecànics, químics o combinats, i (ii) la desestructuració consisteix en aplicar energia mecànica per individualitzar les fibres pretractades, obtenint així fibres de diàmetres nanomètrics The current growth in the demand for nanocellulose in the market, as a consequence of its excellent physico-mechanical properties, makes it imperative development of cellulose nanofiber (CNF) production technologies a large scale that allow to reduce production costs and to have information in real time of the process Nanocellulose provides the opportunity to reinvent materials in different sectors, while at the same time proposing many challenges in the characterization, design, processing and scaling. For the production of CNF, two consecutive stages are generally followed: (i) the pretreatments, which can be mechanical, chemical or combined, and (ii) la destructuring consists of applying mechanical energy to individualize the fibers pretreated, thus obtaining fibers with nanometric diameters

The transition of nanocellulose production from laboratory to industrial scale requires robust monitoring systems that keeps a quality control along the production chain. The present work aims at providing a deeper insight on the main factors affecting the rheological behavior of (ligno)cellulose micro/nanofibers (LCMNFs) and cellulose micro/nanofibers (CMNFs) and how they could correlate with their characteristics. To this end, 20 types of LCMNFs and CMNFs were produced combining mechanical refining and high-pressure homogenization from different raw materials. Aspect ratio and bending capacity of the fibrils played a key role on increasing the viscosity of the suspensions by instigating the formation of entangled structures. Surface charge, reflected by the cationic demand, played opposing effects on the viscosity by reducing the fibrils' contact due to repulsive forces. The suspensions also showed increasing shear-thinning behavior with fibrillation degree, which was attributed to increased surface charge and higher water retention capacity, enabling the fibrils to slide past each other more easily when subjected to flow conditions. The present work elucidates the existing relationships between LCMNF/CMNF properties and their rheological behavior, considering fibrillation intensity and the initial raw material characteristics, in view of the potential of rheological measurements as an industrial scalable characterization technology Authors wish to acknowledge the financial support of the Spanish Economy and Competitiveness Ministry to the Project NANOPROSOST (references CTQ2017-85654-C2-1-R and CTQ2017-85654-C2-2-R), as well as the support of Universidad Complutense de Madrid and Banco de Santander for the grant of J.L. Sanchez-Salvador (CT17/17). Also thanks to the Spanish Ministry of Science and Innovation for the Juan de la Cierva aid of Cristina Campano (Ref. FJC2019-040298-I) and the Spanish National Centre of Electronic Microscopy for the support during image acquisition. Marc Delgado-Aguilar is a Serra Húnter Fellow Open Access funding provided thanks to the CRUE-CSIC agreement with Elsevier

The specific surface area (SSA) of cellulosic or lignocellulosic fibers is seldom reported in the recent literature on papermaking, despite its close relation with the degree of refining and other key pulp properties. Amidst outdated assays (Pulmac permeability test) and methods that, while accurate, are of doubtful usefulness for papermaking purposes (N2 adsorption–desorption), we suggest a methodology based on the cationic demand. A commonly used cationic polyelectrolyte, poly(diallyldimethylammonium chloride) (PDADMAC), became adsorbed onto thermomechanical pulp samples. Then, a potentiometric back titration with an anionic polyelectrolyte measured the cationic demand, expressed as microequivalents of PDADMAC per gram of pulp. Multiplying this value by the surface area of a microequivalent of polymer, considering rod-like conformation in the case of minimum ionic strength, yielded the SSA of the lignocellulosic pulp. Our system assumes that the quaternary ammonium groups were anchored through electrostatic and ion–dipole interactions. Measuring the carboxyl content allowed for discriminating between both kinds of forces. Finally, the model could be validated by plotting the estimated SSA values against the Schopper-Riegler degree, attaining high correlation coefficients (R2 ~ 0.98). Owing to the high molecular weight of the polyelectrolyte of choice (107 kDa), and more particularly in the case of fine-free pulps, SSA values estimated from the cationic demand were consistently lower than those from dye (Congo red) sorption. Instead of being a drawback, the limited diffusion of PDADMAC through fibers can enable papermakers to attain a more helpful quantification of the available surfaces in operations with low residence times Authors wish to acknowledge the financial support of the Spanish Ministry of Economy and Competitiveness to the Project NANOPROSOST, Reference CTQ2017-85654-C2-1-R. Marc Delgado-Aguilar is a Serra Hu´nter Fellow Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature

Fiberboards are used in a variety of applications that can be for interior as well as for exterior. However, their production involves the consumption of virgin wood fibers and the use and production of formaldehyde-based adhesives, with the consequent impact on the environment and health. The removal of these adhesives results in a significant loss of physico-mechanical properties. To confront these major problems, the use of wheat straw, an agricultural waste, as raw material for the production of binderless fiberboards has been explored. As an alternative to synthetic adhesive, enzymatic treatment of fiber and lignocellulose nanofibers (LCNFs) addition, as well as their combination, have been studied. The different treatments produce an important increase in the mechanical properties in front of the untreated fiber and commercial fiberboard, being the combination of both which presents the best results. Separately, the enzymatic treatment produces a greater strengthening effect than the addition of LCNF. In terms of structural stability, the addition of LCNFs and treatment combinations shows the best results for water absorption and thickness swelling. The results obtained show the possibility to obtain fiberboards without synthetic adhesives with mechanical properties far superior to commercial fiberboardsas as such as bending strengths higher than 100 MPa, flexural modulus 5.5 GPa, internal bond 1.6 MPa, and 122.52 kJ/m2 of impact strength with an estimated added cost of 1 /m3 Open Access funding provided thanks to the CRUE-CSIC agreement with Elsevier

The growing concern about environmental pollution has generated an increased demand for biobased and biodegradable materials intended particularly for the packaging sector. Thus, this study focuses on the effect of two different cellulosic reinforcements and plasticized poly(3-hydroxybutyrate) (PHB) on the properties of poly(lactic acid) (PLA). The cellulose fibers containing lignin (CFw) were isolated from wood waste by mechanical treatment, while the ones without lignin (CF) were obtained from pure cellulose by acid hydrolysis. The biocomposites were prepared by means of a melt compounding-masterbatch technique for the better dispersion of additives. The effect of the presence or absence of lignin and of the size of the cellulosic fibers on the properties of PLA and PLA/PHB was emphasized by using in situ X-ray diffraction, polarized optical microscopy, atomic force microscopy, and mechanical and thermal analyses. An improvement of the mechanical properties of PLA and PLA/PHB was achieved in the presence of CF fibers due to their smaller size, while CFw fibers promoted an increased thermal stability of PLA/PHB, owing to the presence of lignin. The overall thermal and mechanical results show the great potential of using cheap cellulose fibers from wood waste to obtain PLA/PHB-based materials for packaging applications as an alternative to using fossil based materials. In addition, in situ X-ray diffraction analysis over a large temperature range has proven to be a useful technique to better understand changes in the crystal structure of complex biomaterials.

Novel biobased materials from fungal hyphae and cellulose fibers have been proposed to address the increasing demand for natural materials in personal protective equipment (PPE). Materials containing commercially available kraft fibers (KF), laboratory-made highly fibrillated hemp fibers (HF) and fungal fibers (FF) obtained from fruiting bodies of lignicolous basidiomycetes growing in nature were prepared using paper production techniques and evaluated for their mechanical and air permeability properties. SEM and microscopy revealed the network structure of materials. The tensile index of materials was in the range of 8&ndash, 60 Nm/g and air permeability ranged from 32&ndash, 23,990 mL/min, depending on the composition of materials. HF was the key component for strength, however, the addition of FF to compositions resulted in higher air permeability. Chemical composition analysis (Fourier-transform infrared spectroscopy) revealed the presence of natural polysaccharides, mainly cellulose and chitin, as well as the appropriate elemental distribution of components C, H and N. Biodegradation potential was proven by a 30-day-long composting in substrate, which resulted in an 8&ndash, 62% drop in the C/N ratio. Conclusions were drawn about the appropriateness of fungal hyphae for use in papermaking-like technologies together with cellulose fibers. Developed materials can be considered as an alternative to synthetic melt and spun-blown materials for PPE.

The construction sector is one of the most demanding of raw materials that exist at present. In turn, the greenhouse gas emissions that it produces are important. Therefore, at present there are several lines of research in which industrial by-products are incorporated for the manufacture of bituminous mixtures and the reduction of CO2 emissions, framed inside the circular economy. On the base of the aforementioned, in this research, bituminous mixtures of the Stone Mastic Asphalt type were developed with electric arc furnace slag, ladle furnace slag and discarded cellulose fibers from the papermaking industry. To this end, the waste is first characterized physically and chemically, and its properties evaluated for use in bituminous mixtures. Later, different groups of samples are conformed with conventional materials and with the waste in order to be able to compare the physical and mechanical properties of the obtained bituminous mixtures. The physical tests carried out were bulk density, maximum density and void index, as well as the Marshall test for the evaluation of the strength and plastic deformations of all the bituminous mixtures manufactured. The study and evaluation of the results showed that the incorporation of slag makes it possible to absorb a greater percentage of bitumen and obtain better mechanical properties, while maintaining a similar deformation and void content. Therefore, it is feasible to use the mentioned slags to create sustainable, resistant and suitable pavements for important traffic.

Trošenje neobnovljivih resursa i ispuštanje velikih količina ugljičnog dioksida(CO2) dovelo je do potrebe pronalaženja ekološki i ekonomski prihvatljivih materijala. Danas se u svijetu pokušavaju pronaći efikasna rješenja kao zamjena za sintetička vlakna. Korištenje celuloznih vlakana u kompozitima pokazalo je svoje prednosti. U radu su izrađeni uzorci morta ojačani vlaknima brnistre tretiranih morskom vodom, uzorci su ispitani na savojnu i tlačnu čvrstoću te su dobiveni rezultati uspoređeni sa prijašnjim istraživanjima., Consumption of non-renewable resources and the release of large amounts of carbon dioxide(CO2) has led to the need to find environmentally and economically acceptable materials. Today the world is trying to find effective solutions as a replacement for synthetic fibers. The use of cellulose fibers in composites has shown its advantages. In this paper, mortar samples with spanish broom fibers treated with sea water were made, the samples were tested for flexural and compressive strength, and the obtained results were compared with previous research.

X-ray microtomography (XμCT) combined with a material testing unit (MTU) is used to obtain 3D images of fiber samples while tensile testing them. The thickness of the sample is analyzed as a function strain percentage. The results indicate thickening on fiber samples during the straining. The method has potential to provide essential new information of complex structures under forced deformation.