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After the production cycle of latex, Hevea brasiliensistrees becomeresidual living plants for this activity, although their woody trunks are still potentially subject to industrial utilization. Bio-composites derived from rubberwood particles were manufactured using two different configurations as a strategy to examine the potential of this species with respect to mechanical behavior. Homogeneous panels were developed from particles at the saturation condition, and heterogeneous panels were obtained from dry particles conditioned at 12% moisture content. Both examples were heat-pressed and glued with castor oil-based polyurethane resin. Density, short-term water absorption and thickness swelling, modulus of rupture and modulus of elasticity in the static bending and perpendicular tensile were evaluated. Panels derived fromrubberwood particles proved to be viable according to the technical standards.

Tectona grandis wood presents decent dimensional stability as well as highly suitable physical and mechanical properties. These characteristics have encouraged the intense usage of this species, which also includes the reuse of wood processing waste for panel production. Using teak wood waste, this study aims to manufacture and evaluate heat-pressed particleboards at 5 MPa and 100 °C, by being glued with castor oil-based polyurethane resin at proportions of 10% for the homogeneous boards and 12% for the heterogeneous solutions. Single-layer (homogeneous) boards were compared with three-layer particleboard specimens (heterogeneous) having the finer particles in the outer layers. The basic density, moisture content, modulus of rupture and modulus of elasticity in the static bending and perpendicular tensile, water absorption, and thickness swelling after 24 h were evaluated to support this comparative study. All the manufactured particleboards met the standardized requirements of performance, thus being very feasible for usage as non-structural boards. When the two different compositions were analyzed, a considerably better performance of the three-layered particleboards was identified when compared to the homogeneous panels.

Hybrid nanocomposite hydrogels, as admixtures for internal curing of cementitious materials, have been widely studied. This study analyzes the effect of applying 0.5% (wt/wt cement) of pre-soaked hydrogels based on polyacrylamide, carboxymethylcellulose, and three different concentrations of Cloisite-Na+ (0, 10, and 20% wt/wt) on the fresh and hardened properties of cementitious mortars. In general, all mortars with hydrogel decreased the consistency index, mainly M20, due to the high concentration of Cloisite-Na+ that modifies the release kinect of the hydrogel. The results showed a slight variation, with an overall average value of 99% water retention in all mortars. This behavior is due to the portion of hydrogel-mortars dosage water retained to reduce the availability of free water in the mixture because this amount of water is stored, a priori, within the polymer particles. At 28 d, the mortars produced with hydrogels containing 20% of nanoclay (M20) exhibit mechanical behavior similar to the reference mortar (M), which corroborates the percentage of voids found. Scanning electron microscope images confirm that the M and M20 mortars are uniform and possess few pores or microcracks. Thus, these hybrid hydrogels have the potential to be innovative materials for water control improvements in cementitious materials technology.

Diante da crescente preocupação com os impactos ambientais relacionados ao uso de polímeros sintéticos, estudos visando à obtenção e aplicação de materiais poliméricos de fontes renováveis vêm aumentando, como por exemplo, o desenvolvimento de filmes comestíveis à base de polímeros naturais. Com isso, este trabalho teve como objetivo produzir filmes comestível e biodegradável por meio de uma matriz de polissacarídeos (goma arábica, carboximetilcelulose e alginato de sódio) com adição de óleo essencial (OE) de erva doce para possível utilização em embalagens primária de mistura de bolo de caixinha. Os filmes obtidos foram avaliados quanto a análise de espessura, permeabilidade ao vapor de água (WVP), solubilidade e propriedades mecânicas. As espessuras dos filmes foram diferentes, pois as condições de preparo nem sempre são as mesmas. Os valores de WVP aumentaram significativamente, em média 150 %, em relação aos filmes de controle com a incorporação de emulsão de OE e principalmente a goma arábica (GA). Com a adição de GA nos filmes de AS e CMC, diminuiu a tensão máxima e a elongação, pois uma quantidade menor de energia foi requerida para a ruptura do filme quando este sofreu um estresse mecânico. A solubilização dos filmes, em condições próximas ao preparo de um bolo na batedeira, mostrou-se eficiente. Com o desenvolvimento dessa pesquisa, foi possível atingir o objetivo inicial de obter uma solução filmogênica satisfatória e a formação de uma embalagem comestível contendo polissacarídeos e emulsão de óleo essencial de erva-doce.

Made available in DSpace on 2021-06-25T10:36:52Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-10-14 Cellulose is everywhere and renovates in nature continuously and rapidly, while petroleum does not. Unlike the latter, cellulose biodegrades and may represent a carbon sink. Inspired by the multiscale architecture of cellulose, we report on all-cellulose composites comprising cellulose ether as a matrix and highly pure bacterial cellulose nanocrystals (BCNCs) as fillers. Optimum performance as a packaging material was achieved by engineering BCNC surface chemistry as well as the filler-in-matrix dispersion, targeting the replacement of unsustainable, fossil-derived plastics intended for single-use applications. Cost could pose a hurdle, eliminated through the valorization of underutilized scraps from industrial operations, which is also in line with the circular bioeconomy in terms of the integral use of biomass. As far as performance, the optically transparent hydroxypropyl methylcellulose (HPMC) films presented improved tensile strength (from 61 ± 6 to 86 ± 9 MPa) and Young's modulus (from 1.5 ± 0.2 to 2.7 ± 0.4 GPa) while reduced elongation at break (from 15 ± 2 to 12 ± 2%) and water vapor permeability (from 0.40 ± 0.02 to 0.31 ± 0.01 g mm h-1 m-2 kPa-1) when filled with only 5 wt % of (120 ± 31) nm long, (13 ± 3) nm wide, 88% crystalline BCNC. This dual, win-win effect of BCNCs on the mechanical and barrier properties of HPMC films was enabled by a suitable dispersion state, achieved via high-energy mixing, and quenched by casting. This study adds to the current literature on all-cellulose composites and helps pave the route for the technical and economical feasibilities of replacing non-renewable, non-biodegradable plastics in short-term applications by materials that are both renewable and biodegradable, that are also produced through green protocols and isolated from surplus biomass, and that still perform similarly or even better. Grupo de Compósitos e Nanocompósitos Híbridos (GCNH) Department of Physics and Chemistry Ilha Solteira School of Engineering São Paulo State University (UNESP) Institute of Chemistry University of Campinas (UNICAMP) Laboratory of Biopolymers and Biomaterials (BioPolMat) University of Araraquara (UNIARA) Grupo de Compósitos e Nanocompósitos Híbridos (GCNH) Department of Physics and Chemistry Ilha Solteira School of Engineering São Paulo State University (UNESP)

Hidrogéis compostos em polímeros naturais que tenham sido usados em diferentes setores devido a suas propriedades de biocompatibilidade, biodegradabilidade, custo relativamente baixo e atoxicidade. O objetivo deste estudo foi preparar hidrogéis de alginato / amido reticulados com diferentes ícones (Mn 2+ , Zn 2+ ou Ca 2+ ), incluir zeólito ou nanoclay, e avaliar o efeito do reticador e nanoestrutura na adsorção e comportamento de seleção do herbicida paraquat. Os hidrogéis e seus nanocompósitos foram preparados por imersão de soluções de alginato / amido, alginato / amido / nanoclay ou alginato / amido / zeólita em recipientes que recebem uma solução reticuladora (MnCl 2 , ZnCl 2ou CaCl 2 ) a 25 ° C. Todos os hidrogênios apresentaram boa capacidade de adsorção, principalmente os hidrogênios nanoestruturados com nanoclay e zeólito. Como recursos polares, selecione alta interação com moléculas de paraquat. O comportamento da liberação também foi muito interessante, sendo que a quantidade de solução de formação de nanocompósitos de hidrogel pode controlar a liberação de paraquat, que tipos de materiais podem ser usados como veículos de transporte no sistema de liberação controlada.

RESUMO A madeira trata-se de uma matéria-prima de fonte renovável amplamente utilizada pelo setor da construção civil devido às suas características de fácil manuseio e processabilidade, boas propriedades mecânicas, sustentabilidade, entre outros. Por se tratar de um material de origem vegetal faz-se necessário a realização de um tratamento preservativo antes de sua aplicação na construção civil. Neste contexto, a busca de novas soluções como opção de tratamento superficial biodegradável para garantir melhoria das propriedades das madeiras é uma das necessidades a serem sanadas para que o material apresente um bom desempenho e amplie sua durabilidade. Assim, tratamentos por imersão em emulsões de óleos essenciais (OE) no material, como uma alternativa de mitigar a ocorrência de patologias comuns na madeira, demonstra-se ser uma opção potencialmente inovadora para o setor moveleiro e da construção civil. O presente estudo objetivou avaliar os efeitos dos tratamentos de hidrofobização e odorização da madeira após a inserção de óleos essenciais nas condições de nanoemulsão, emulsão e óleo puro. Para tanto, foram utilizadas amostras de madeira do tipo Hymenaea sp popularmente conhecida como Jatobá devido a suas características de alta resistência mecânica, odor forte e de comum aplicação na construção civil. Os óleos essenciais utilizados foram de melaleuca (Melaleuca alternifólia) e copaíba (Copaifera Officinalis), devido às suas propriedades antimicrobianas, antifúngicas, antissépticas e odor característico. A aplicação por imersão nas amostras de madeira foi realizada nas seguintes condições: emulsão 25% (m/m) de OE de melaleuca; emulsão 25% (m/m) de OE de copaíba; nanoemulsão 2% (m/V) de OE de melaleuca; nanoemulsão 2% (m/V) de OE de copaíba e a aplicação dos mesmos óleos puros. Os resultados demonstraram que a suspensão que apresentou maior retenção foi a nanoemulsão, sendo OE de copaíba 44,10% e OE de melaleuca 40,41% em relação a massa da amostra sem tratamento. As emulsões resultaram em 21,32% para OE de copaíba e 20,51% para OE de melaleuca e, na condição de óleo puro, a retenção observada foi de 15,11% para o OE de melaleuca e 23,82% para o OE de copaíba. Os resultados obtidos podem estar relacionados a característica hidrofílica da madeira, sendo que a suspensão mais aquosa foi a mais absorvida. Através do ensaio de Microscopia Eletrônica de Varredura (MEV) foi possível identificar uma cobertura uniforme das amostras para o óleo puro, um aspecto rugoso de cobertura para a emulsão e uma superfície mais fendilhada e ressecada nas amostras com nanoemulsão. O ensaio de ângulo de contato não apresentou um aumento significativo na hidrofobicidade das amostras, com resultados positivos de 7°±9° a 23°±15°, sendo que na condição de nanoemulsão diminuiu 12°± 9° em comparação com a amostra não tratada para o OE de copaíba e 16°± 9° para o OE de melaleuca, indicando uma maior permeabilidade de água. ABSTRACT Wood is a raw material from renewable source widely used by the construction industry due to its characteristics of easy handling and processability, good mechanical properties, sustainability, among others. Since it is a vegetal material, it is necessary to perform a preservative treatment before its application in civil construction. In this context, the search for new solutions as an option for biodegradable surface treatment to ensure the improvement of wood properties is one of the needs to be addressed so that the material performs well and increases its durability. Thus, treatments by immersion in emulsions of essential oils (EO) in the material, as an alternative to mitigate the occurrence of common pathologies in wood, proves to be a potentially innovative option for the furniture and construction industries. The present study aimed to evaluate the effects of hydrophobing and wood odorization treatments after the insertion of essential oils in nanoemulsion, emulsion, and pure oil conditions. The essential oils used were melaleuca (Melaleuca alternifolia) and copaiba (Copaifera officinalis), due to their antimicrobial, antifungal, antiseptic properties, and characteristic odor. The immersion application on the wood samples was conducted under the following conditions: 25% (w/w) melaleuca EO emulsion; 25% (w/w) copaiba EO emulsion; 2% (w/w) melaleuca EO nanoemulsion; 2% (w/w) copaiba EO nanoemulsion and the application of the same pure oils. The results showed that the suspension that presented the highest retention was the nanoemulsion, being OE of copaiba 44.10% and OE of melaleuca 40.41% in relation to the mass of the untreated sample. The emulsions resulted in 21.32% for OE copaiba and 20.51% for OE melaleuca, and in the pure oil condition, the observed retention was 15.11% for melaleuca OE and 23.82% for OE copaiba. The results obtained may be related to the hydrophilic characteristic of the wood, and the most aqueous suspension was the most absorbed. Through the Scanning Electron Microscopy (SEM) test it was possible to identify a uniform coverage of the samples for the pure oil, a rough aspect of coverage for the emulsion and a more cracked and dried surface in the samples with nanoemulsion. The contact angle test did not show a significant increase in hydrophobicity of the samples, with positive results from 7°±9° to 23°±15°, and in the nanoemulsion condition it decreased 12°± 9° compared to the untreated sample for copaiba EO and 16°± 9° for melaleuca EO, indicating a higher water permeability.

The concern about consuming eco-friendly products has motivated research in the development of new materials. Therefore, films based on natural polymers have been used to replace traditional polymers. This study consists of a production of films based on gelatin reinforced with black pepper essential oil-loaded nanoemulsions and Cloisite Na+. The films were characterized by water vapor permeability, mechanical and thermal properties, surface contact angle, X-ray diffraction and scanning electron microscopy. It was observed that the films containing the nanoemulsion have higher permeability values and an increase in their mechanical resistance. The addition of nanoclay contributed to an increase in the surface hydrophobicity of the film and an increase in the tensile strength at break by about 150%. The addition of essential oil nanoemulsions led to an increase in thermal stability. The presence of clay dispersion contributed to the formation of a surface that was slightly rougher and grainier. The addition of the black pepper essential oil nanoemulsion resulted in an increase in porosity of the gelatin matrix. Through X-ray diffraction analysis, it was possible to conclude that both the polymeric gelatin matrix and the essential oils nanoemulsion are intercalated with the clay dispersion.

Every year, the residues generated by the disposal of packaging materials produced from fossil fuels have been growing, denoting a major environmental problem that can be mitigated by the development of biodegradable materials from natural polymers, particularly edible films. This work aimed at the development of pectin films added by cupuassu puree and chitosan nanoparticles and to evaluate the improvement of the physical-mechanical performance of the composite films. The nanostructures displayed an average size of 110 nm and a zeta potential of approximately +40 mV. The films were produced by casting, and they exhibited manageability, homogeneity, and continuity. Based upon the mechanical analysis of maximum stress and elongation, it was concluded that the nanoparticles functioned as fillers, increasing the toughness of the pectin films. Water vapor permeability assays demonstrated that the nanostructured films containing cupuassu exhibited improved barrier properties. The glass transition temperature of the films was not strongly affected by the addition of nanoparticles. Conversely, the initial degradation temperature decreased with the addition of nanoparticles and cupuassu puree. The outcomes of this research pave a new route for the development of nonconventional food packaging materials.

O objetivo deste trabalho foi produzir filmes biodegradáveis com nanopartículas de quitosana em matriz de pectina. As nanopartículas foram obtidas por condensação de refluxo e os filmes foram produzidos pela técnica de casting, utilizando-se uma solução filmogênica composta por nanopartículas de quitosana (NPsQs) e pectina. As nanopartículas em solução foram caracterizadas quanto ao seu tamanho, através de espalhamento dinâmico de luz (DLS) e sua estabilidade, medida pelo potencial Zeta. Os filmes foram analisados por Espectrometria de Infravermelho com Transformada de Fourier (FT-IR). Os filmes obtidos apresentaram uma superfície bastante homogênea. DOI: http://dx.doi.org/10.30609/JETI.2019-7766

O processo de embalagem de alimentos é de imensa importância quando se trata de preservação de alimentos frescos ou processados. A maioria desses materiais são fabricados com plásticos sintéticos e sua eliminação representa um problema ambiental. Este estudo teve como objetivo preparar e caracterizar filmes compostos de biopolímeros, alginato de sódio (AS) e carboximetilcelulose (CMC), com adição de goma arábica e óleo essencial de erva doce. A análise de ângulo de contato mostra que os filmes são hidrofílicos. A superfície dos filmes apresentou estrutura firme, densa e coesa, porém com algumas rugosidades. Nas micrografias das amostras de filme contendo óleo essencial de erva doce nota-se estruturas parecidas com cristais sobre a matriz polimérica de CMC e AS. A umidade dos filmes foi, no geral, baixa (média de 14 %). Os menores percentuais de umidade apresentados foram para os filmes com de óleo essencial. Os filmes são biodegradáveis, esse processo ocorre, pois, as macromoléculas naturais, como proteínas, polissacarídeos, celulose e goma geralmente são degradáveis em sistemas biológicos pela hidrólise seguida de oxidação. Portanto, foi satisfatório a formação de embalagem comestível contendo polissacarídeos e emulsão de óleo essencial de erva-doce.

A producao de biofilmes e revestimentos polimericos a base de polimeros naturais, a fim de aplica-los como embalagens de alimentos e alvo de constantes pesquisas, devido a necessidade de diminuir o volume de embalagens plasticas descartadas e otimizar as propriedades e validade dos alimentos. Dentre a imensa variedade de polimeros utilizados para esse fim, a carboximetilcelulose (CMC) destaca-se por apresentar caracteristicas favoraveis para a formacao de solucoes filmogenicas, alem de ser biodegradavel e apresentar baixo custo. Visando potencializar as propriedades naturais desse polimero, pesquisadores tem utilizado aditivos que sao incorporados a solucao filmogenicas como nanoparticulas de quitosana (NSQ) e Curcuma longa (C). A quitosana tambem e um polimero natural, amplamente utilizado em aplicacoes nos campos da farmacologia, tecnologia de biomateriais, biomedicina, agricultura e industrias cosmetica e alimenticia. A Curcuma longa derivada do acafrao, apresenta propriedade antioxidantes e antimicrobianas, que tem despertado bastante interesse, principalmente na industria alimenticia, visando a substituicao de antioxidantes sinteticos por esses materiais naturais. Neste trabalho, foram preparadas nanoparticulas de quitosana por gelificacao ionotropica e incorporadas ao polimero (CMC), juntamente com a Curcuma longa, com o intuito de reforcar e potencializar as propriedades naturais desse polimero, para a preparacao de biofilmes comestiveis. Apos a preparacao, caracteriza-los atraves de analises das propriedades mecânicas, permeabilidade ao vapor de agua e ângulo de contato. Palavras-chave: biofilmes comestiveis; polimeros naturais; nanoparticulas de quitosana; curcuma longa

Made available in DSpace on 2021-06-25T10:26:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 This study investigated the effect of different surface-charged lamellar materials on the swelling and diffusion properties of synthesized polyacrylamide-methylcellulose hydrogels (HG). Montmorillonite and thermally activated hydrotalcite (300 °C and 550 °C) were incorporated during the preparation of nanocomposite (NC) hydrogels. A series of NC hydrogels were prepared by varying the lamellar material content (1:1, 2:1 and 4:1). The results showed that the HG with hydrotalcite (550 °C) was strongly dependent on the ionic intensity, and that the swelling degree increased by 50%, 65% and 78% with reducing the hydrotalcite content at (1:1), (2:1) and (4:1), respectively. The water absorption capacity of HG containing montmorillonite or hydrotalcite (300 ºC) was slightly affected when the pH was decreased from 7 to 3. However, the pH variation from 7 to 10 increased the water absorption capacity of most HG, except those containing hydrotalcite (550 °C) at (2:1) and (4:1). The presence of lamellar nanoparticles in hydrogels made the polymer matrix more rigid, and less likely to absorb water. In contrast, HG with hydrotalcite (550 °C) at (2:1) and (4:1) showed anomalous behavior with an increase in their water absorption capacity. The results support that the developed NC-HG can be suitable candidate materials for controlled released applications. Universidade Federal de São Carlos, Rodovia Washington Luiz, km 235 Laboratório Nacional de Nanotecnologia para o Agronegócio (LNNA) Embrapa Instrumentação, Rua 15 de Novembro 1452 Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP) Instituto de Química Avenida Professor Francisco Degni, 55, Jardim Quitandinha Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), Avenida Brasil, 56 Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP) Instituto de Química Avenida Professor Francisco Degni, 55, Jardim Quitandinha Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), Avenida Brasil, 56

Made available in DSpace on 2021-06-25T10:56:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Zeolite-based nanocomposites have become an efficient option for application in herbicide removal and controlled release systems. Our group previously described the degree of swelling in water and salt solutions, spectroscopic and structural properties, and fertilizer desorption from carboxymethylcellulose-poly(methacrylic acid-co-acrylamide)-zeolite nanocomposites. Here, morphological and thermal properties, and swelling degree studies at different pH was investigated in these same nanocomposites. Their water-uptake in these various swelling media was correlated with sorption and desorption profiles of diquat. SEM-EDX technique indicated the presence of zeolite in the nanocomposites, as well as the increase in the quantity of water hydration molecules trapped in the zeolite cavities was confirmed by DSC. Improved diquat sorption from 8.3 to 9.4 mg/g was recorded when 1.5% zeolite was added into nanocomposites, indicating a significant increase in herbicide–matrix interaction. This increase also led to a small decrease in the desorption process, but in a more controlled manner. Variation of pH of the swelling media might have changed the elasticity of nanocomposite chains, which in turn adjusted release rate. A better understanding of nanocomposite–herbicide interaction can help design novel matrices with enhanced pesticide sorption, contributing to reduce contaminations caused by the indiscriminate use of agrochemicals. Grupo de Compósitos e Nanocompósitos Híbridos (GCNH) Department of Physics and Chemistry Ilha Solteira School of Engineering São Paulo State University (UNESP) Grupo de Compósitos e Nanocompósitos Híbridos (GCNH) Department of Physics and Chemistry Ilha Solteira School of Engineering São Paulo State University (UNESP)

Magnetic hydrogels are considered smart materials because they can respond to the magnetic field, and in some case, it can also present other sensibilities, like temperature, pH, etc. It can be obtained employing various techniques. Generally, their synthesis consists of a polymeric matrix and at least one magnetic component. The synthesis methods include the most common physical interactions (mixing method) and chemical crosslinking method (grafting method). Hydrogels and magnetic hydrogels can be used in different ways, since biomedical applications until agriculture and the environment. This diversity is based on their properties such as biodegradability, biocompatibility, atoxicity, absorption capacity, hydrophilicity. Beyond these properties, the incorporation of these magnetic particles is relatively easy, producing composites with good stability. It is believed that magnetic hydrogels will soon be able to replace existing materials with the full capacity both for application and for acceptance by the consumer likely.

The use of natural polymers, such as gelatin and other proteins, has increased in an attempt to replace part of the consumption of petroleum-based packaging. This study evaluated the influence of green tea extract and lemon nanoemulsion on mechanical, thermal and permeability properties of gelatin matrix. The results showed that green tea increased the gelatin tensile strength (TS) from 86 ± 7 MPa to 101 ± 5 MPa, on the other hand, the nanoemulsion decreases to 78 ± 8 MPa. The incorporation of green tea and nanoemulsion enhanced the water vapor permeability of gelatin film; this could be due to the interacting with the hydrophobic domains of gelatin. This was indicated by melting point (Tm) in differential scanning calorimetry (DSC) and degradation temperatures in the thermogravimetric analysis (TG), respectively. Changes in FTIR spectra of gelatin film were observed when the green tea and nanoemulsion were incorporated. Therefore, this study showed a new characterization and formulation of gelatin films incorporated by green tea extract and lemon nanoemulsion and their potential for edible film.

Made available in DSpace on 2018-12-11T17:20:45Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-09-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Universidade Estadual Paulista Polymeric hydrogels are important biomaterials with potential for various applications including the controlled release of drugs. Clay and zeolite nanostructures can enhance the absorption and release properties of hydrogels. In our previous work, a procedure was optimized for making hydrogel beads. The objectives of this study were to use the optimized bead forming procedure to prepare clay and zeolite nanocomposite hydrogel beads and characterize their microstructure, thermal and chemical properties. The hydrogels were prepared by dripping solutions of either sodium alginate or sodium alginate/nanostructure (clay and/or zeolite) into beakers containing different concentrations of CaCl2 at 25 °C. Fourier transform infrared spectroscopy (FTIR) analysis detected the presence of functional groups associated with alginate, clay and zeolite. The microstructure of the alginate beads was somewhat rough with small protrusions. Flakes were visible in micrographs of beads containing nanoclay. The elemental composition of the hydrogels was investigated by energy dispersive X-ray spectrometry (EDX). EDX spectra revealed magnesium, sodium, aluminum, silicon and increased the levels of oxygen in the nanoclay compositions. The incorporation of nanoclays decreased the percentage of organic matter lost as detected by thermogravimetric analysis (TG). TG was also able to detect the incorporation of nanoclay in hydrogels. The nanoclays proved to be more effective than zeolites in producing alginate hydrogels with satisfactory swelling characteristics. Grupo de Compósitos e Nanocompósitos Híbridos (GCNH) Department of Physics and Chemistry Programa de Pós-Graduação em Ciência dos Materiais São Paulo State University (Unesp) School of Engineering, Ilha Solteira Bioproduct Research Unit USDA-ARS WRRC Grupo de Compósitos e Nanocompósitos Híbridos (GCNH) Department of Physics and Chemistry Programa de Pós-Graduação em Ciência dos Materiais São Paulo State University (Unesp) School of Engineering, Ilha Solteira FAPESP: 2013/03643-0 CNPq: 405680/2016-3

Made available in DSpace on 2018-12-11T17:34:28Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-03-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) The use of fertilizer and water availability are essential factors limiting the agricultural production. The controlled release technology is very promising because it allows the maintenance of fertilizer concentrations within an ideal range avoiding inefficiency and toxicity problems, minimizing the environmental impacts and improving their efficiency. In this context, the nanostructured hydrogels appear as a possible carrier vehicle for these controlled release systems due to their inherent properties, such as biodegradability, low toxicity, and cost, rapid absorption and desorption controlled capacity of water and solutes. In this work, we performed the synthesis of nanostructured hydrogels based on poly(methacrylic acid) (PMAA)/Cloisite-Na+ via free radical polymerization. SEM images indicated a similarity in the basic structure of all nanocomposites. The porous diameter of the hydrogels increased with increasing of nanoclay content. EDS analysis showed the ions belonging to nanoclay present in the nanocomposites, confirming the formation of true nanocomposites. TG–DTG and DSC techniques confirmed an improvement in the thermal stability of nanocomposites caused by the addition of nanoclay. For instance, the degradation initial temperature of the hydrogel was increased from 198.5 to 203.5 °C, and inversely, the degradation rate of the 2° thermal event was decreased from 0.694 to 0.472% min °C−1, when the nanoclay was increased from 0 to 20 mass/%. Moreover, the controlled release investigation showed an improvement in the release time and quantity of the fertilizer released with nanoclay content. This result is very required for this specific application. Grupo de Compósitos e Nanocompósitos Híbridos (GCNH) Programa de Pós-Graduação em Ciência dos Materiais School of Engineering São Paulo State University (Unesp) Departamento de Química Universidade Federal de São Carlos (UFSCar) Grupo de Compósitos e Nanocompósitos Híbridos (GCNH) Programa de Pós-Graduação em Ciência dos Materiais School of Engineering São Paulo State University (Unesp)

Grupo de Compositos e Nanocompositos Hibridos (GCNH) Faculdade de Engenharia de Ilha Solteira UNESP - Univ. Estadual Paulista Programa de Pos-graduacao em Ciencia Dos Materiais

O objetivo deste trabalho foi sintetizar bionanocompositos hibridos a partir da acrilamida, polissacarideo carboximetilcelulose e nanoargila e avaliar as propriedades fisico-quimicas, tais como: hidrofilicas, cineticas, morfologicas e espectroscopicas. Os hidrogeis foram preparados fixando as concentracoes de acrilamida em 6% m/v e carboximetilcelulose em 1% m/v, e incorporando diferentes concentracoes de nanoargila (cloisita-Na + ) (0-20 % m/v). A tecnica de difracao de raios-x permitiu notar que as plaquetas de nanoargila se encontram intercalada na matriz polimerica. A tecnica de microscopia eletronica de varredura indicou uma morfologia de estruturas porosas, com formas bem definidas e tamanhos de poros heterogeneos. A analise termica evidenciou uma estabilidade termica abaixo de 200 oC para todas as amostras analisadas. Os resultados das propriedades hidrofilicas e cineticas em agua destilada e em solucoes salinas indicaram que as concentracoes de nanoargila e o efeito da carga ionica influenciam o intumescimento e os parâmetros cineticos. A constante de perda de agua indicou que a presenca de nanoargila proporcionou uma liberacao controlada de agua destilada. Portanto, as propriedades fisico-quimicas indicam que estes bionanocompositos hibridos sao uma alternativa promissora para aplicacao na agricultura, sendo sua potencialidade investigada na parte II deste trabalho.

O objetivo deste trabalho foi testar o efeito de hidrogel biodegradavel (composto por 6% m/v de acrilamida e 1% m/v de carboximetilcelulose) e seus bionanocompositos contendo diferentes concentracoes de nanoargila (0-20% m/v) incorporados em um substrato de cultivo utilizado para germinacao e desenvolvimento de mudas de alface ( Lactuca sativa). Os experimentos foram conduzidos com um delineamento inteiramente casualizado. O primeiro experimento estudou doses crescentes de hidrogel incorporado no substrato. O segundo experimento avaliou os bionanocompositos com crescentes concentracoes de nanoargila. Os parâmetros analisados foram indice de velocidade de germinacao, porcentagem de germinacao, diâmetro do caule, massa fresca e seca, tamanho da raiz e alturas das partes aerea e total da planta. No primeiro experimento, notou-se que a aplicacao de 5% foi a que apresentou os melhores resultados na germinacao e o desenvolvimento do cultivo de alface. As aplicacoes dos bionanocompositos demonstraram resultados positivos em todos os parâmetros analisados, causando tambem um melhor desenvolvimento do sistema radicular (segundo experimento). Sendo que os bionanocompositos contendo 20% de nanoargila foram os mais promissores. Portanto, os hidrogeis e os bionanocompositos otimizam a germinacao da hortalica Lactuca sativa , demonstrando ser um produto promissor para a aplicacao na agricultura.

The objective of this paper was to study the effect of pH, concentration and ionic species on the water absorption of the bionanocomposite hydrogels based on carboxymethylcellulose polysaccharide and laponite nanoclay. Bionanocomposite hydrogels were obtained via free radical polymerization. It was possible to observe that the swelling degree (Q) and kinetic properties were strongly influenced, and controlled, by the presence and quantity of ionic species, decreasing their water uptake when compared to the same values obtained in distilled water. Furthermore, the addition of nanoclay decreased the water uptake sensibility of the hydrogel in ionic media. It was also observed that the presence of the nanoclay decreased the Qeq distilled water values from 32.5 g g-1 to 22.5 g g-1. The pKa variation of the bionanocomposites was a good indication of the possible interaction of the nanoclay-polymeric chains. The possibility of the control of water absorption (velocity and quantity) whereas these nanocomposites are pH- and salt-responsive may potentiate their application in agriculture. Agronomical studies are in progress, which can confirm its applicability in this area.

Os hidrogéis utilizados como polímeros de liberação controlada podem contribuir para o melhor desenvolvimento das reações de hidratação das partículas de cimento ao longo do tempo e, minimizar a retração na microestrutura da matriz cimentícia, através de uma cura interna mais efetiva. Este estudo propôs otimizar a metodologia de síntese de pastas cimentícias e efetuar a análise morfológica e mecânica de compósitos híbridos, obtidos a partir do uso de hidrogéis com cimento Portland. Inicialmente, foram sintetizados hidrogéis compostos por poliacrilamida polissacarídeo carboximetilcelulose, para que posteriormente fossem aplicados na confecção de pastas com cimento Portland, variando a concentração do polímero (0,5, 1,5 e 2,5% de hidrogel), aplicando diversas relações água/cimento (a/c = 0,3, 0,325, 0,35 e 0,4) e diferentes tipos de cimentos. As amostras foram submetidas a ensaios de compressão axial, determinação de densidade aparente e análise de microscopia eletrônica de varredura (MEV). A partir dos resultados obtidos, observou-se que a concentração de 0,5% de hidrogel foi a que apresentou um desempenho mais satisfatório, assim como a relação a/c = 0,35 apresentou um aumento de 1,09% na resistência mecânica aos 28 dias. Com relação ao tipo de cimento, o CPII-Z-32 foi o que demonstrou um aumento da resistência ao longo do tempo. A análise de densidade não demonstrou variações significativas, que pode estar relacionado a formação de produtos hidratados com o aumento do tempo de cura. A técnica de microscopia eletrônica de varredura (MEV) permitiu identificar que o hidrogel foi homogeneamente incorporado na matriz cimentícia, visto que não foi observado separação de fases entre o polímero e o cimento. Assim, a aplicação de compósitos híbridos passa ser uma alternativa para o desenvolvimento de materiais cimentícios que utilizam o procedimento de cura interna, para evitar retração. DOI: http://dx.doi.org/10.30609/JETI.2019-7474

Devido à contínua necessidade de desenvolver materiais cada vez mais leves, mas que se enquadrem as severas normas de resistência mecânica exigida, a indústria aeronáutica vem impulsionando direta ou indiretamente o desenvolvimento de novos materiais compósitos estruturais ou o melhoramento dos materiais já empregados atualmente. Neste sentido, neste trabalho foi otimizada a metodologia de obtenção de compósitos baseados em fibra de carbono e resina epóxi visando aplicação em longarinas de Aerodesigns. Foi investigado o efeito do número de camadas fibra de carbono-resina epóxi, temperatura e tipo de laminação na densidade e nas propriedades mecânicas e morfológicas dos compósitos. Os resultados demonstraram boa reprodutibilidade na preparação dos compósitos, independente da metodologia aplicada, e que as propriedades mecânicas podem ser controladas pelos efeitos supracitados. A densidade dos compósitos obtidos pela laminação a vácuo foi em torno de 10 % menor em relação aos obtidos pela laminação manual. Além disso, tais compósitos apresentaram um acabamento melhor e mais refinado, em relação a laminação manual. Estes resultados podem auxiliar na projeção de longarinas utilizando novos materiais compósitos, nos quais são desenvolvidos por estudantes pertencente ao Projeto de Extensão Universitária Zebra Aerodesign da Unesp de Ilha Solteira – SP. DOI: http://dx.doi.org/10.30609/JETI.2019-7607

Made available in DSpace on 2021-06-25T10:17:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-12-01 Cement is a material widely used in civil construction due to its physical and chemical properties, ensuring a good performance. Some polymeric materials, such as hydrogels, have been frequently added to improve these properties and mitigate autogenous retraction in cementitious matrices. This paper aimed to evaluate the influence of polymeric hydrogel on the fresh and hardened properties of cementitious pastes (water/binder ratio = 0.35). Fresh properties results showed that the consistency and exudation indexes of these matrices decreased with an increase in the amount of hydrogel. The values of the bulk density of all cementitious matrices are around 2.1–2.2 g cm−3. Matrices containing up to 1.0% of hydrogel have satisfactory mechanical properties, reaching compressive strength of 60 MPa for 112 days of curing age. From these results, it is possible to conclude that hydrogels are promising materials for civil engineering applications, acting mainly as a filler and hydroretentor agent. Grupo de Compósitos e Nanocompósitos Híbridos (GCNH) Department of Physics and Chemistry Programa de Pós-Graduação em Ciência dos Materiais São Paulo State University (Unesp) School of Engineering Institute Federal of São Paulo (IFSP) Grupo de Compósitos e Nanocompósitos Híbridos (GCNH) Department of Physics and Chemistry Programa de Pós-Graduação em Ciência dos Materiais São Paulo State University (Unesp) School of Engineering

Made available in DSpace on 2020-12-12T01:12:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-06-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Universidade Estadual Paulista In this paper, a series of novel poly(methacrylic acid)/laponite RDS (PMAA/Lap RDS) nanocomposite hydrogels crosslinked by N,N’-methylene bisacrylamide were synthesized via free radical polymerization by using potassium persulfate as initiator. The main novelty of this paper refers to the detail investigation of how the laponite RDS influenced of the pKa, and consequently, the water-uptake of these nanocomposites. In parallel, the evidence of incorporation and interactions of the materials was confirmed by scanning electron microscopy and Fourier transform infrared spectra techniques. By the X-ray diffraction technique (XRD), it was possible to confirm the exfoliation/intercalation configuration of the nanoclay laponite RDS (Lap RDS) into the PMAA matrix. Hydrophilic properties, measured by swelling degree (SD), indicated that the presence of Lap RDS influenced the water uptake capability of the nanocomposite, reaching a maximum of 91 ± 2 g/g for nanocomposites constituted by 5 % of nanoclay. Besides, the pKa of the nanocomposite can be adjusted by nanoclay content. In this way, the ability of these hydrogels to respond to pH values can be useful to act as trigger in controlled release systems. Grupo de Compósitos e Nanocompósitos Híbridos (GCNH) São Paulo State University (Unesp) School of Engineering Grupo de Compósitos e Nanocompósitos Híbridos (GCNH) São Paulo State University (Unesp) School of Engineering

The growth in global population has caused an increase in the demand for food production, leading to an increase in the use of agrochemicals. Their overuse causes serious damage to the environment. In this way, nanocomposite hydrogels are promising materials for use as carrier vehicles for the controlled release of agrochemicals, which helps reduce the damage caused by their indiscriminate use. In this work, a novel hydrogel nanostructure based on carboxymethylcellulose (CMC) and zeolite with a poly(methacrylic acid)-co-polyacrylamide (PMAA-co-PAAm) support network was synthesized. The CMC polysaccharide increased the zeolite stability in the solution. Increasing the concentration of acrylamide (AAm) monomer improved the mechanical stability of the nanocomposites. FTIR, XRD and TG results confirmed the presence of zeolite in the PMAA-co-PAAm matrices. In addition, the zeolite decreased the water absorption of the nanocomposites from 33 ± 2 g/g to approximately 22 ± 1 g/g, but increased the thermal stability of the nanocomposites. However, the reduction in water absorption in saline solutions was more significant in hydrogels without zeolite. Fertilizer desorption studies confirmed the controlled release behavior and this trend may be improved by zeolite structure. Thus, the presence of zeolite increased the amount of monobasic potassium phosphate (KH2PO4) release from 250 to 275 mg of fertilizer per gram of hydrogel. Controlling the water absorption and kinetic properties by adjusting the nanocomposite constituents may increase the applicability of the composites in agriculture, specifically as carrier vehicles in the controlled release of agrochemicals.

In this paper, series of novel nanocomposite hydrogels based on polyacrylamide (PAAm), carboxymethylcellulose (CMC) and nanoclay were synthesized. Hydrophilic, kinetic, spectroscopic and morphological properties were investigated as function of their constituents. Spectroscopic properties confirmed the obtaining of the nanocomposites. It was also observed that the nanocomposites have walls of pores with a more rugged morphology compared with the morphology of the hydrogel without clay, contributing to repel the water molecules. Besides, the results showed that the velocity and quantity of water uptake may be controlled by adjusting of matrix rigidity, i.e., nanoclay content into polymeric matrix. This behavior is required to future application in agriculture fields, specifically as carrier vehicle in controlled release of agrochemicals. Thus, these nanocomposites have technological application.

International audience; Over the last decade, nanocellulose-based nanocomposite hydrogels have emerged as promising materials in different fields of application such as medicine, food, and agriculture. The present review addresses the advances in the synthesis methods and technological applications of these hydrogels. Different chemical and physical cross-linking methods used for the design of cellulose nanocrystals, cellulose nanofibrils, and bacterial cellulose hydrogels are discussed in detail. Nanocomposite hydrogels based on nanocellulose or reinforced with nanocellulose have good mechanical properties, biocompatibility, and biodegradability and allow the incorporation of several molecules or solutes, which can provide a slow and controlled release profile. The major advances exploring these hydrogels in biomedicine, food, and agriculture are reviewed. Finally, challenges and environmental issues related to their production are briefly discussed.