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Phosphorylated fibers offer a broad range of applications, particularly in thermal insulation, notably with wood fibers, provided they exhibit improved mechanical characteristics. Despite encountering challenges in applying traditional papermaking methods, the creation of paper or board sheets with phosphorylated pulp fibers remains a challenge. Findings suggest that phosphorylation-modified fibers show increased roughness. Moreover, in comparison with unbeaten kraft sheets (KF) and thermomechanical pulp sheets (TMP), those made from phosphorylated kraft fibers (PKF), using a cationic coagulant and a flocculant, demonstrate significant enhancements in burst index, break index, and tensile energy absorption by 2.12 times, 1.7 times, and 2.77 times, respectively. Similarly, phosphorylated TMP sheets, prepared with a dual polymeric system (coagulant/flocculant), exhibit improvements of 1.42 times, 1.33 times, and 1.82 times, respectively, in these properties. The study emphasizes the ameliorating effect of cationic polymeric agents on the charge impact of phosphorylated fibers on overall sheet quality, while also highlighting the substantial influence of hot-pressing lignin-containing paper on all determined physical properties. [ABSTRACT FROM AUTHOR]

The three cellulosic key chromophores, 2,5-dihydroxy-[1,4]-benzoquinone, 5,8-dihydroxy-[1,4]-naphthoquinone and 2,5-dihydroxy-acetophenone, are nearly ubiquitous in cellulosic materials because of their special structures and resonance stabilization with highly delocalized double bonds that renders them thermodynamically very stable and resistant towards bleaching. All of these compounds possess acidic hydroxyl groups. The current work explores the derivatization of these OH groups by a phosphitylation agent followed by 31P NMR analysis, an approach that is very frequently used for quantitative OH group analysis and differentiation in lignins and lignin derivatives. The chemical shifts are reported and structural peculiarities of the chromophore derivatives are discussed. The 31P NMR approach adds to the toolbox of methods applicable in cellulose chromophore analysis, bleaching and aging studies. [ABSTRACT FROM AUTHOR]

Banana stem is a known alternative to wood for the production of pulp and paper. During the production of paper, it is extremely important to save costs and time while at the same time enhancing quality of produced paper. In the present study, paper was developed from banana stem fiber by optimizing its density. Response surface methodology (RSM) using Box-Behnken design (BBD) was used to determine optimum blending parameters of the developed papers. The influence of banana stem fiber amount (250-1000 g), water amount (1-2liters) and blending time (5-10 min) on paper density was ana)lyzed using software Stat-Ease 360, Version 13. The optimum conditions of banana stem fiber amount, water amount and blending time to achieve a density of 675.75 g/m3 were determined as 461.83 g, 1.31liters, and 8.53 min, respectively. ANOVA results revealed that the quadratic model best fits the density response, with blending time and banana stem fiber amount as the most significant model terms. Linear effects were more predominant than quadratic and interaction effects. The developed density model was in close agreement with experimental findings with an R² value of 0.9748. Developed paper had cellulosic contents, with volatiles as high as 82.11%wb and 2.11% wb ash composition. Future works on thermal properties of paper are encouraged. [ABSTRACT FROM AUTHOR]

The production of release coatings has been increasing in recent years because of their use in various fields. However, commercially available release coatings are regarded as non-recyclable. As a consequence, the repulping of these residues is difficult, and their presence in the recycling stream represents an important source of contamination. One solution to this problem is to use new coating materials that can replace the siliconized backing, provided that these new materials are recyclable. As a solution to this problem, the authors propose the use of alkylated phosphorylated fibers to produce an environmentally friendly and inexpensive release paper. The results show that a surface application of hydrophobic phosphorylated fibers reduces the surface free energy of the paper support, as well as the peel strength, which facilitates the separation of the adhesive tape. [ABSTRACT FROM AUTHOR]

This paper presents the limitations and potential of ATR-FTIR spectroscopy applied to the study of cellulosic textile collections The technique helps to differentiate natural fibres according to the content of lignin, pectin, hemicellulose, and wax, although some problematic issues should be considered. The spectral differences derived from the environmental humidity uptake and the plant composition are reviewed and discussed in the light of new experimental data. Diagnostic bands are proposed that can discriminate between different fibres from different plants. The contribution of ageing is also considered, demonstrating that sometimes aged fibres cannot be reliably recognised. In contrast, the potential of ATR-FTIR spectroscopy to discriminate between natural and modified fibres is discussed and proven. The best results were obtained when microinvasive ATR-FTIR spectroscopy was coupled with SEM observations. The proposed protocol was tested on microsamples of various cellulosic materials from traditional Japanese samurai armours dating from the 16th to the 20th centuries (Morigi Collection, Museo delle Culture, Lugano, Switzerland). The results facilitated a complete characterisation of the materials and demonstrated that the protocol can be used to study a wide variety of cellulosic materials, including both natural and man-modified fibres, and paper. [ABSTRACT FROM AUTHOR]

This publication presents the results of the fundamental research on the interaction of laser radiation and lignocellulosic fibres with respect to the melting of the fibre main components cellulose, hemicellulose and lignin. In the first part, hand sheets made of different lignocellulosic fibres were irradiated with laser radiation from a carbon monoxide laser. Fluence-dependent interaction regimes, the dynamics of flash pyrolysis and chemical changes due to irradiation are discussed. Using a high-speed camera, an intermediate liquid state could be observed as a result of the irradiation. This is decomposed into gaseous reaction products by a highly dynamic boiling process. In addition to the time-resolved investigations, extensive FTIR studies were carried out. The second part is intended to further investigate former work on melting of cellulose. The basic idea is to combine laser radiation and mechanical pressure by compressing the sample between two steel bolts and simultaneously irradiating the joint. The processed samples show some visual indications of intermediate melting, such as increased transparency or flow behaviour. However, these can be traced back to effects that do not require a melting state. [ABSTRACT FROM AUTHOR]

Superhydrophobic and strong cellulosic paper was fabricated in a two-step process consisting of heavy refining and dip coating with PDMS (trimethylsiloxy-terminated poly (dimethylsiloxane)) and Hf-SiO2 (hydrophobic fumed silica) solution. Results showed that the heavy refining produced extensive fibrillated fibers, which significantly increased the tensile strength. Meanwhile, the density of the paper sheet increased, and the porosity decreased. Benefiting from these changes, the subsequent dip coating operation was improved, producing paper with a very high water contact angle (WCA), yet with a low up-take of the hydrophobic solution. Finally, superhydrophobic paper sheets were fabricated with 155o WCA and 1o sliding angle (SA). At the same time, its tensile strength increased by 12.7 fold (from 0.85 MPa of the original paper to 10.8 MPa), with additional benefits, such as high transparency (75% at 550 nm). The superhydrophobic and strong paper is highly desirable for high value-added utilization of fiber. [ABSTRACT FROM AUTHOR]

Three commercially-available conductive filaments were evaluated for 3D printing flexible circuits on paper. While all three filaments were printed successfully, the resulting conductive traces were found to have significantly different impedances when characterized by electrochemical impedance spectroscopy. Using a graphite-doped polylactic acid filament, the flexibility of paper-based conductive traces was evaluated, methods of integrating common electrical and electronic components with the conductive traces were demonstrated, and the resistive heating of the traces was characterized. The ability to 3D print conductive traces on paper using commercially available materials opens many opportunities for rapid prototyping of flexible electronics and for integrating electronic circuits with paper-based microfluidic devices. [ABSTRACT FROM AUTHOR]

• 72% − 80% of fibre was recovered from disposable coffee cups. • 2% and 3% consistency shredded cups required > 100 kWh/tonne to repulp with 3 refiner passes. • Pulp quality did not significantly diminish after repulping using a single-disk refiner. Over 64 billion paper-plastic laminate (PPL) coffee cups are consumed between the United States and Canada annually, the majority accumulating in landfills due to a hydrophobic plastic inner-lining. Recycling can mitigate environmental damage and provide economic value from repurposed products. We found that standard repulping methods were insufficient to separate fiber from plastic due to the low intensity of treatment. To increase process intensity, we mechanically refined shredded PPL coffee cups and Kraft eucalyptus sheets (control) at 2%, 3%, and 4% consistencies with three passes to determine the energy required to separate fibers from plastic and the effects on fiber quality. 2% and 3% consistency PPL cups measured under 40 kWh/tonne of input material for one refiner pass and ∼ 80 kWh/tonne for 4% consistency PPL cups. Recovered fiber fraction totaled 87.7%, 85.3%, and 80.5% of input mass of Kraft eucalyptus and 72.3%, 72.6%, and 79.6% of input mass of PPL cups at 2%, 3%, and 4% consistency, respectively. Fines content of PPL cups jumped from 8% pre-refining to ∼ 30% post-refining while Kraft eucalyptus fibers were unaffected, suggesting that breaking the plastic-fiber bonds results in fines generation. Mean fiber length of PPL cups slightly decreased with consistency and tensile strength improved. Freeness decreased with consistency only in PPL cup samples. These results demonstrate a low energy requirement to effectively separate fiber and plastics in PPL cups as well as minimal impact on fiber quality using existing refining technology, and provides an estimate of the financial costs of local recycling efforts. [ABSTRACT FROM AUTHOR]

This contribution focuses on understanding of paper wet-strength properties, by taking a closer look at the spatial distribution of wet-strengthening polymers inside the cellulosic fiber network deposited under different treatment conditions using confocal laser scanning microscopy as in situ imaging tool. We compare the behavior of paper samples treated with a photochemically cross-linkable copolymer using an impregnation process employing three different solvents, namely water, 2-propanol (IPA) and 1-butanol (BuOH), respectively. As these solvents swell paper fibers to quite different extents, the deposition of the polymer, on, in or in-between the cellulosic fibers varies quite strongly, as is shown by in-depth analysis using confocal laser scanning microscopy. The difference in accessibility of distinct surface sites exclusively on or also in and between the fibers controls the macroscopic tensile strength under both dry and wet conditions. [ABSTRACT FROM AUTHOR]

Xylan is primarily found in the secondary cell wall of plants providing strength and integrity. To take advantage of the reinforcing effect of xylan in papermaking, it is crucial to understand its role in pulp fibers, as it undergoes substantial changes during pulping. However, the contributions of xylan that is added afterwards (extrinsic) and xylan present after pulping (intrinsic) remain largely unexplored. Here, we partially degraded xylan from refined bleached softwood kraft pulp (BSKP) and adsorbed xylan onto BSKP. Enzymatic degradation of 1 % xylan resulted in an open hand sheet structure, while adsorption of 3 % xylan created a denser fiber network. The mechanical properties improved with adsorbed xylan, but decreased more significantly after enzymatic treatment. We propose that the enhancement in mechanical properties by adsorbed extrinsic xylan is due to increased fiber-fiber bonds and sheet density, while the deterioration in mechanical properties of the enzyme treated pulp is caused by the opposite effect. These findings suggest that xylan is decisive for fiber network strength. However, intrinsic xylan is more critical, and the same properties cannot be achieved by readsorbing xylan onto the fibers. Therefore, pulping parameters should be selected to preserve intrinsic xylan within the fibers to maintain paper strength. [Display omitted] [ABSTRACT FROM AUTHOR]

The main structural component of wood fibers is cellulose, which, being highly hydrophilic, interacts with water. Cellulose‐based paper has, therefore, the same affinity with water. However, for most products such as decorative paper, this is more of a disadvantage, where water uptake both as liquid and from humid air not only weakens the paper by breaking hydrogen bonds but also alters its dimension and stability over time. The dimensional stability (ability of the paper to retain the size as its moisture content changes) is a critical parameter when the paper is submitted to printing, copying, and converting operations. Humidity can cause sheet wrinkling or warping, thus compromising the processability and the results achievable. The modification of fibers with chemical additives can be a way to improve the performance of paper against water and water vapor uptake. For this reason, several tests of horizontal diffusion of solvents were carried out to evaluate the change in uptake of as‐is paper and of papers modified by several different chemical treatments. Solvent uptake tests were performed to assess the interaction of chemically treated and untreated papers with water, dichloromethane, and ethanol. Diffusion mechanisms of the solvents flow within the fiber networks and their movement through the porous solids were analyzed. The chemical treatments of the fiber with silane, siloxane, and polyelectrolyte multilayer were found to considerably influence both solvent contact angles and absorption times of the papers, thus affecting the rate of solvent (more interestingly, of the water) diffusion into the fiber wall. By comparing all the treated and untreated samples, the contact angles with the solvents decreased by performing siloxane, oligo‐siloxane, and silane treatments. More specifically, the diffusivity rates of water decreased because of the disappearance of a fraction of the hydrophilic sites and the onset of higher crystallinity regions on the paper sheets. [ABSTRACT FROM AUTHOR]

In this work, barium sulfate (BS) fibers with a three‐level nanorod‐assembled hierarchical structure have been synthesized in a large scale by the barium oleate precursor hydrothermal method. A new kind of anti‐acid and anti‐alkali fire‐resistant BS inorganic paper has been developed using BS fibers, glass fibers and inorganic adhesive, and it has advantages such as high flexibility, good tensile strength, excellent fire‐resistant properties, excellent corrosion resistance to strong acids and strong alkalis. It is expected that the anti‐acid anti‐alkali fire‐resistant BS paper has promising applications under various high‐temperature and harsh conditions. [ABSTRACT FROM AUTHOR]

Holocellulose fibers produced by mild delignification form strong fiber networks, without beating or dry-strength agents. Recently, sequential batch delignification using peracetic acid (PAA) on finely cut wood sticks resulted in high-quality holocellulose fibers. Here, single step PAA delignification is developed for wood chips, which is simpler and can be used for larger fiber batches (400 g) with similar, high yield (60%). Such fibers have 1.4% lignin, 25% hemicelluloses content and well-preserved cellulose and hemicellulose molar mass. The corresponding paper sheet materials with a porosity of ~ 50%, have a Young's modulus of 9 GPa and a strength of 90 MPa. Holocellulose fibers can now be readily investigated for use in larger scale paper, molded fiber and polymer biocomposite materials applications, or for cellulose nanofibril preparation. [ABSTRACT FROM AUTHOR]

A computationally efficient method to study the in-plane and out-of-plane dimensional instability of thin paper sheets under the influence of moisture changes is presented. The method explicitly resolves the bonded and the free segments of fibers in the sheet, capturing the effect of anisotropic hygroexpansion at the fiber level. The method is verified against a volumetric model. The importance of longitudinal fiber hygroexpansion is demonstrated in spite of the absolute value of longitudinal hygroexpansion being an order of magnitude lower than the transverse hygroexpansion component. Finally, the method is used to demonstrate the formation of macroscopic sheet curl due to a moisture gradient in structurally uniform sheets in the absence of viscoelastic or plastic constitutive behavior and through-thickness residual stress profiles. [ABSTRACT FROM AUTHOR]

This study analyzed the effect that pulp fibers have on the surface softness component of hygiene paper. The surface softness component has more of an influence on the evaluation of subjective softness results than the bulk softness component. Using the surface softness measurement technique, this study aimed to evaluate the effect that fibers have on the softness of hygiene paper substrate via objective numerical values to measure the surface softness component of hand sheets composed of various pulp species. The results indicate that coarseness effects had the largest effect on softness among the various fiber characteristics, such as average fiber length, width and coarseness. As fiber coarseness increased, a rough surface formed, which resulted in an increase in the mean deviation from the average friction (MMD). Nonwood fibers had long fiber length and low coarseness, which enables the production of hygiene paper with high strength and softness. This study hopefully could lead to the development of various process technologies that may improve the softness of hygiene paper products. [ABSTRACT FROM AUTHOR]

The porous, cellulosic fiber networks in commercial paper are generally regarded as continuum materials when the sheet is large compared to the size of fiber agglomerates (flocs). In this manuscript we reveal that even when the average macroscopic tensile response of copy paper specimens is well described by orthotropic anisotropy, the local deformation characteristics inside a specimen and among different specimens are not uniform as predicted by continuum theories. Using a non-contact, high resolution full-field strain measurements, we present specimen orientation specific strain maps and deformation fields. The characteristic length scales of strain hot spots are obtained using thresholding and lineal path correlation and are compared to the characteristic size of flocs. We quantify the spatial distribution and extent of nonaffine (non-continuum) deformations during tensile loading of a commercial paper, and show how they are critical features of deformation and tearing mechanisms in paper. [ABSTRACT FROM AUTHOR]

Information on industrial paper obtained from special purpose heat-resistant and fire-resistant fibers by the method of fiber swelling is presented. Results of a study of the effect of fiber cutting length on the mechanical properties the paper are presented. Corresponding dependencies are established. [ABSTRACT FROM AUTHOR]

With the increase in demand for wood and wood products, there is need to find alternative sources for the production of pulp and paper. Non wood plants have attracted interest due to their short growth cycles, moderate irrigation and fertilizer requirements and low lignin content. This study aimed at investigating the fibre characteristics of Agave sisalana for pulp and paper production. Leaves were collected from three sisal plant stands in Oyo State, Nigeria. The plant whorl was divided systematically into bottom, middle and top from which five leaves were randomly collected from each whorl position. The fibres of the leaves were extracted from which 2cm of fibres were taken from three positions on the leaf (top, middle and base). Extracted fibres were macerated and 3375 fibres were measured. The result shows that the fibre length of sisal increased with increasing length of the leaves from base to top with a mean value of 1.68mm. The fibre diameter and cell wall thickness averaged 16.98µm and 2.32µm respectively decreasing from the stem base to the top. The slenderness ratio averaged 99.4 while the coefficient of flexibility averaged 72.61. The highest value of the runkel ratio of Agave sisalana was 0.42. The fibres from sisal (Agave sisalana) leaves possess good fibre dimensions and derived values which will make it suitable for the production of high quality paper. [ABSTRACT FROM AUTHOR]

Wood is versatile, inexhaustible and renewable. These made the wood an outstanding material used in different domain such as raw material for production of pulp, paper and fibre based products. In Nigeria, one of the problems in pulp and paper industry is inadequate supply of long fibre for paper production. Also, overexploitation of materials having desirable fibre characteristic was observed. Therefore, there is need to research into lesser known wood species so as to ascertain its suitability for paper making. This study presents the potential of Aningeria robusta wood as source for adequate fibres for paper making. Samples of 20x20x20mm were collected from the three trees of Aningeria robusta wood at different position; base (10%), middle (50%) and top (90%) along the merchantable height and prepared into slivers of 3mmx10mm for examination of the fibre characteristics. Thereafter, it was macerated and viewed under microscope. Further morphological indices were calculate accordingly. The mean fibre length, fibre diameter, lumen, cell wall thickness (CWT), slenderness, flexural ratio and runkel ratio were 1.55mm, 11.71µm, 8.78µm, 1.46, 132.12, and 75.07 respectively. Variation of indices along sampling heights were not significant except for CWT. A. robusta has shown good properties and could be added to already known wood species suitable for paper making. [ABSTRACT FROM AUTHOR]

Abstract: Previously unreported line patterns visible under ultraviolet light were observed on a proportion of plain white A4 printer/copier paper from different manufacturers. These Ultraviolet Line Patterns (UVLPs) usually appear as stripes down the vertical length of the paper. Typically, the UVLPs were found to “repeat” through the ream in a predictable way, while also changing. It is postulated that the repeating nature of the UVLPs is a result of the way that paper is manufactured. This leads to the ability to sequence the sheets compared to their original source paper. Even in the absence of UVLPs, it is possible to use our observation of the manufacturing process to anticipate the order of several sheets of paper and conclusively associate them, in some cases, by physically fitting their machine cut edges and crossing paper fibers. Such a novel approach to examining questioned documents would be highly useful in forensic casework. [ABSTRACT FROM AUTHOR]

Understanding water absorbency in paper is challenging as fibre swelling and out-of-plane deformation occur simultaneously during liquid imbibition. Liquid absorption is commonly accessed by gravimetric tests, which provides limited information on the local spatial and temporal distribution of fluid in the substrate. In this work, we developed iron tracers to map liquid imbibition in paper by in situ precipitation of iron oxide nanoparticles during passage of the wetting front. The iron oxide tracers were found to be robustly attached to the cellulosic fibres. After liquid absorption tests, absorbency was investigated by mapping the distribution of iron in 3D using X-ray micro-computed tomography (μCT) and in 2D using energy-dispersive X-ray spectroscopy. We demonstrate a difference in tracer distribution between the wetting front and the fully saturated region supporting that imbibition proceeds in two phases, i.e. liquid percolation through the cell wall initially prior to filling of the external pore spaces. Critically, we demonstrate that these iron tracers enhance image contrast and allow for new imaging modalities in μCT for fibre networks. [Display omitted] [ABSTRACT FROM AUTHOR]

The article presents information on creation of a coating which would meet the requirements of defect free surfaces at the time of handling paper coils. Polyurethane coating samples were tested by material property characterization tool XRD as well as a surface roughness tester to know their structural and morphological features after load testing.

To protect forest resources and increase the value of agro-industrial residues, it would be helpful to produce paper-based materials from non-woody or recycled fiber resources. This study investigated the reinforcement mechanism of bacterial cellulose (BC) on paper sheets made from different sources including softwood, hardwood, sugarcane bagasse, bamboo, wheat straw, and recycled fiber, which represent a selection of high quality, medium quality, and low quality fibers. The results showed that by maintaining BC addition at a low level of 0.5-1.5% (total paper dry weight), the paper sheets made from high and medium quality fibers have the maximum tensile index improvement, with 5-25%. The tensile index of low quality fiber including wheat straw pulp and recycled fiber pulp increased slightly and gradually with the level of BC addition; at 5% BC addition, the tensile indexes increased by 9 and 40%, respectively. To investigate the BC reinforcement mechanism, different fiber characteristics, SEM images of BC reinforced paper, BC retention rate on paper, and the effects of dispersant addition were evaluated. It was found that high BC addition or retention rate in paper sheets do not necessarily result in good BC reinforcement effects but that proper dispersion of BC is important. [ABSTRACT FROM AUTHOR]

A new concept for fluid flow manipulation in microfluidic paper-based analytical devices (μPADs) is presented by introducing ionogel materials as passive pumps. μPADs were fabricated using a new double side contact stamping process and ionogels were precisely photopolymerised at the inlet of the μPADs. The ionogels remain mainly on the surface of the paper and get absorbed in the superficial paper-fibers allowing for the liquid to flow from the ionogel into the paper easily. As a proof of concept the fluid flow and mixing behaviour of two different ionogels μPADs were compared with the non-treated μPADs. It was demonstrated that both ionogels highly affect the fluid flow by delaying the flow due to their different physical and chemical properties and water holding capacities. [ABSTRACT FROM AUTHOR]

This review describes the state-of-the-art of material derived from the forest sector with respect to its potential for use in the packaging industry. Some innovative approaches are highlighted. The aim is to cover recent developments and key challenges for successful introduction of renewable materials in the packaging market. The covered subjects are renewable fibers and bio-based polymers for use in bioplastics or as coatings for paper-based packaging materials. Current market sizes and forecasts are also presented. Competitive mechanical, thermal, and barrier properties along with material availability and ease of processing are identified as fundamental issues for sustainable utilization of renewable materials.

A análise morfométrica das fibras das folhas de Astrocaryum murumuru var. murumuru Mart. revelou que as fibras do pecíolo apresentaram comprimento e espessura da parede superiores às regiões da ráquis e folíolo, com médias variando de 1.266,09 µm a 3.270,56 µm e 5,56 µm a 10,67 µm, respectivamente. Em relação ao índice de Runckel e coeficiente de flexibilidade, as regiões pecíolo e ráquis obtiveram valores considerados favoráveis para sua utilização na indústria papeleira e, o índice de enfeltramento demonstrou que provavelmente as fibras dessas regiões apresentarão uma boa resistência ao rasgo quando submetidas às avaliações físico-mecânicas. Diante dos resultados, a espécie se revela promissora como fonte alternativa de matéria-prima para a produção de papel, sendo necessários, entretanto, estudos de resistências físico-mecânicas a consolidação deste pré-diagnóstico.The analysis morphometric of the leaf fibers of Astrocaryum murumuru var. murumuru Mart. demonstrated that the petiole's fibers had presented length and wall thickness superiors than the rachis and leaflets, with yours means varying of 1.266,09 µm to 3.270,56 µm and 5,56 µm to 10,67 µm, respectively. In relation the index of Runckel and flexibility's coefficient the petiole and rachis had gotten values considered favorable for its use in the paper industry and, the felting index it probably demonstrated that the fibers of these regions will present good crash resistance when submitted to the evaluations physical-mechanical. therefore, the results show the species is a alternative source of raw material to produce paper, but its necessary to do physical-mechanical resistance studies to consolidate this pre diagnostic.

The tensile response of dense fiber-based materials like paper or paperboard is mainly dependent of the properties of the fibers, which store most of the elastic energy. In this paper, we investigate the influence of geometrical and material parameters on the mechanical response of the pulp fibers used in paper manufacturing. We developed a three-dimensional finite element model of the fiber, which accounts for microfibril orientation of cellulose fibril, and the presence of lignin in the secondary cell wall. The results showed that the change in the microfibril orientation upon axial straining is mainly a geometrical effect, and is independent of the material properties of the fiber, as long as the deformations are elastic. Plastic strain accelerates the change in microfibril orientation and thus makes it material-dependent. The results also showed that the elastic modulus of the fiber has a non-linear dependency on microfibril angle, with elastic modulus being more sensitive to the change of microfibril angle around small initial values of microfibril angles. Based on numerical results acquired from a 3D fiber model supported by available experimental evidence, we propose an anisotropic-kinematic hardening plasticity model for a fiber within a beam framework. The proposed fiber model is capable of reproducing the main features of the cyclic tensile response of a pulp fiber, such as stiffening due to changing microfibril angle. The constitutive model of the fiber was implemented in a finite-element model of the fiber network. By using the fiber network model, we estimated the level of strain that fiber segments accumulate before the typical failure strain of the entire network is reached. [ABSTRACT FROM AUTHOR]

During 1994 278 million tons of paper were produced worldwide, while around 330 million tons were produced in 2002. The forecast for paper production in 2010 is 420 million tons. From these data, it may be concluded that the paper production industry, which exists for around 2000 years, is still a very attractive industrial branch. This work represents the conditions in the production of the major and auxiliary raw materials for paper production, as well as paper production in the World and production forecasts until 2010. It was indicated that the fraction of secondary fibers obtained from recycled paper increases every year in regard primary fibers. In 2010 secondary fibers will be the major source of primary raw materials for paper production in the World. It was pointed out that in the last fifteen years the quantity of paper produced during one season grew rapidly. This growth was achieved by advance stock preparation of paper and increased velocity of the paper machine and the width web of the produced paper. Activities regarding environmental protection undertaken by manufacturers of paper and fibers are presented.

Significant dimensional variations may occur in paper-based materials when subjected to changes in moisture content. Moisture induced deformations are governed by the swelling of individual fibres, which is transferred through inter-fibre bonds to the entire fibrous network. Complex interactions between mechanical and hygro-expansive properties take place in the bonding areas, affecting the overall material response. In most network models, the role of these inter-fibre bonds is not explicitly incorporated. This work presents a periodic meso-structural model for the discrete fibrous network, which considers the free-standing fibre segments and inter-fibre bonds. Despite its simplicity, the reference unit-cell enables the incorporation of relevant micro- and meso-structural features such as network structure, fibres and bond geometry and hygro-elastic properties. The proposed model is solved analytically through a proper homogenization strategy, allowing to recover the paper’s anisotropic hygro-mechanical response in terms of effective elastic constants and effective hygro-expansive coefficients, exploiting the coupling at the meso-structural level between hygroscopic and mechanical behavior. A comparison with experimental results obtained from the literature shows that the presented approach is quite accurate in predicting the overall paper response, thereby revealing the influence of several meso-scale parameters (e.g. fibre orientation, dimensions, mechanical strength). [ABSTRACT FROM AUTHOR]

Reconstituted parchment is, besides Japanese paper and parchment, a feasible and widely used material for filling in losses in parchment. This study investigates changes in haptic and visual qualities of the material caused by modifications with different ingredients like paper and parchment fibres. Additionally, selected procedures processing parchment to parchment powder were examined. As a brief introduction, the paper gives an overview over the existing types of reconstituted parchment that are used traditionally in parchment conservation. In addition it attempts to clarify the terminology for this material. Parchment powder was produced with simple and readily available equipment, by different methods: sanding, grating, grinding, shredding, milling and ice-crushing. The different types of home-made powder were compared to a pre-fabricated parchment powder obtained from a parchment maker. The test series showed that the type of preparation of parchment powder influences the fibre texture which in turn affects the material's properties visually and haptically. While all methods are clearly more time-consuming than buying ready-touse material, some preparations, e.g. grating, shredding and ice-crushing, showed superior properties. [ABSTRACT FROM AUTHOR]

Roll coating is a comparatively simple and common technology for coating of continuous substrates like paper, coils, or foils, where the fluid is metered through the gap between two rolls. Rolls wrapped with a deformable rubber layer enable a precise metering for low fluid amounts and lead additionally to higher process stability. Many efforts have been made to investigate the influencing factors of deformable roll coating by experimental and numerical methods. Beside configurations with positive gaps, which are comparable to rigid roll setups, negative gaps, where only the elasticity of the rubber layer prevents overlapping of the rolls, are of interest as such configurations enable thin liquid layers. The main influencing factors on the volume flow rate through the gap are viscosity, average velocity, effective radius, Young's modulus, load or pre-set gap height, and partly rubber thickness, when an influence of the layer height is assumed. The dependency is often given in empirically or numerically based power law relationships. In contrast to this, in the present study, an analytically based solution is used to investigate the influencing factors in deformable roll coating with negative gaps. This continues the authors' previous work, in which the analytical solution was derived. As a result, a general agreement with numerical and experimental results from literature is found. Additionally, the analytical approach allows for the first time the ability to quantify further trends. The proposed power law exponent for the dimensionless load and elasticity numbers from literature cannot be considered as constant in the whole common application range of roll coating but remarkable trends appear. Additionally, a new criterion for the critical rubber cover thickness is developed analytically which describes the limit value of the negligible influence of the rubber cover thickness on the volume flow rate. The present investigation enables the explanation of different literature results and offers a more general view in the understanding of roll coating processes. [ABSTRACT FROM AUTHOR]

SUMMARY This paper is concerned with the distributed [ABSTRACT FROM AUTHOR]

Highlights: [•] The Lucas–Washburn equation is inadequate in predicting water intake at short contact times. [•] The Lucas–Washburn equation inadequate for predicting intake as a function of temperature. [•] The absorption rate increase with temperature is controlled by molecular processes. [•] The adsorbed water on fiber surfaces lowers the solid–gas interfacial energy. [ABSTRACT FROM AUTHOR]

ABSTRACT To improve the paper properties of the poly(1,3,4-oxadiazoles) (POD), the POD pulps were prepared by prechemical and mechanical methods to increase their polarity, contact area, and interaction. The fibrillated degree of the staple fibers was evaluated by the Canadian Standard Freeness and the specific surface area, while the surface free energy was calculated by the Micro-wilhelmy method. Meanwhile, the functional groups and compositions on the surface of the POD fibers were confirmed by the FTIR-ATR and the X-ray photoelectron spectroscopy, and the surface morphological structure and the crystalline structure of the POD fibers were observed by the fiber analyzer, scanning electron microscope, and Wide-angle X-ray diffraction, respectively. It was found that the pronounced abrasive and distinctive grooves were formed on the surface of the POD fibers after prechemical and mechanical treatment. The surface free energy of POD fibers increased 8.41%, and the polar part increased by 32.10% after treatment. It was confirmed that the polar functional groups and fibril were formed after chemical and mechanical treatment, so the interaction of the POD fibers was highly enhanced, and as a result the apparent density, tensile strength, fold endurance, and tear strength of the paper formed by those treated fibers were all improved apparently. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39818. [ABSTRACT FROM AUTHOR]

Paper is a material exhibiting a complex microstructure that is composed of a network of fibres at the micro-level. When subjected to external loading or variations in moisture conditions over different time scales, changes in strain that are non-linear with respect to time are observed at the sheet level (macro-scale). In order to investigate this time-dependent behaviour of paper, a creep power law model is implemented within a finite element approach at the level of single fibres. This rate-dependent model is found to capture experimental results available in literature for single fibres with a good agreement (both quantitatively and qualitatively). Based on the identified model at the level of single fibres, the time-dependent hygro-mechanical response is upscaled towards the network scale. To this end, random model networks of ribbon shaped fibres are generated and their response is simulated. The network-scale response, emerging from the rate-dependent fibre model, demonstrates the ability to predict the response of networks subjected to relaxation at a constant moisture level. The developed numerical model predicts lower values of overall stress response in single fibres as compared to networks. Also, stress relaxation predicted by the rate-dependent model in the cross-direction of the networks is in agreement with the experimental observations by Johanson and Kubát (1967). Therefore, one of the remarkable findings of the present work is that the developed rate-dependent model is robust enough to capture the sheet scale response also qualitatively. Based on the study of these computational results, a better understanding is achieved regarding the influence of mechanical and rate-dependent properties of single fibres on the hygro-expansion of complete fibre networks, and in particular of paper sheets. • A rate-dependent non-linear model is developed to study creep in paper networks. • It is calibrated with experiments on the single paper fibres with a good match. • It also captures the experimental response of the networks qualitatively. • One of the remarkable achievement of our work is the robustness of the model. [ABSTRACT FROM AUTHOR]

This review describes the state-of-the-art of material derived from the forest sector with respect to its potential for use in the packaging industry. Some innovative approaches are highlighted. The aim is to cover recent developments and key challenges for successful introduction of renewable materials in the packaging market. The covered subjects are renewable fibers and bio-based polymers for use in bioplastics or as coatings for paper-based packaging materials. Current market sizes and forecasts are also presented. Competitive mechanical, thermal, and barrier properties along with material availability and ease of processing are identified as fundamental issues for sustainable utilization of renewable materials. [ABSTRACT FROM AUTHOR]

The strong matching preclusion number of a graph is the minimum number of vertices and edges whose deletion results in a graph that has neither perfect matchings nor almost-perfect matchings. This is an extension of the matching preclusion problem and has recently been introduced by Park and Ihm.15 In this paper, we examine properties of strong matching preclusion for alternating group graphs, by finding their strong matching preclusion numbers and categorizing all optimal solutions. More importantly, we prove a general result on taking a Cartesian product of a graph with K2 (an edge) to obtain the corresponding results for split-stars. [ABSTRACT FROM AUTHOR]

Abstract: Calendering of paper is an industrial finishing process designed to smoothen its surface so as to improve gloss as well as printability. In this article, we describe how calendering affects paper roughness on both microscopic and macroscopic length scales. We also discuss how these modifications relate to the morphology of the fibers composing the paper sheets. The characterization of the surface is carried out using an optical profilometer and two different species of fibers, as well as their mixture, are used. We first show that calendering induces modifications of the surface on all length scales measured and that these modifications are related by straightforward transformations. We also show that these results hold for papers formed from a mixture of fibers. [Copyright &y& Elsevier]

Abstract: A new two-dimensional network model is proposed as a micromechanics model to simulate paper’s failure process due to sequentially breakages of fibers and/or bonds. Paper is approximated as a network composed of fibers any two of which link to each other by their intersecting point, namely so-called bond. Fibers distribute along three particular directions, leading to network’s macro-level isotropy. In the framework of finite element method, nodes correspond to fiber-to-fiber bonds, while elements are fiber segments between every two neighboring nodes and described by Timoshenko beam theory. Element breaks when its equivalent internal tensile stress reaches the tensile strength of fiber. Strength of nodes, i.e. fiber-to-fiber bonds is assumed to be dependant on shearing interaction between fibers, considering the dominant interaction is shearing in a plane problem. Numerical examples show the model’s capacity of reflecting basic failure characteristic in paper. Influences of fiber length and the ratio of fiber strength to bond strength are analyzed in detail. [ABSTRACT FROM AUTHOR]

Rheological properties of fiber/polymer suspensions and dynamic mechanical analysis (DMA) of paper sheets containing the same polymers were measured. Correlations between viscoelastic properties of suspensions and strength of paper sheet are presented. Rheological properties of suspensions of microfibrillar cellulose (MFC) and a set of water soluble polymers were measured. Rheological properties of these complex fluids vary considerably depending on the added polymer. A suspension of fiber and carboxymethyl cellulose (CMC) exhibits a viscosity higher than the sum of the viscosity of the individual components in the suspension. In contrast, when cationic starch (CS) is used together with the fiber, the yielding behavior rather than the viscosity is characteristic of the suspension. Dynamic mechanical properties of paper sheets containing CMC or CS as additives were studied at different humidity levels. Different yielding behavior observed in oscillatory rheology can be correlated with straining behavior in dynamic mechanical properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [ABSTRACT FROM AUTHOR]

This paper presents an anisotropic damage model to deal with the fragmentation induced by impact loadings on glass samples. As small-scale (i.e. sub-element) damage is described as well as cracks extending above the element scale, an approach referred to as “meso-damage” is developed. The latter, which is based on the knowledge of random distributions of initiation sites, predicts different regimes such as single or multiple fragmentation. The experimental opening crack pattern obtained in edge-on-impact test is reproduced numerically. [ABSTRACT FROM AUTHOR]

Mixtures of stickies-containing and stickies-free pulps were investigated for their deposition potential in an attempt to better understand the interactions of dissolved and colloidal material (DCM) when mixing two different pulps. The filtered pulp mixtures were tested in a deposition apparatus which measures both the dynamic fluid as well as impact deposition by an established optical scanning method. A pulp filtrate of model stickies led to deposition according to the proportion of stickies-containing pulp in the mixture. Other mixtures of pulps, however, led to deposition that differed from the predicted value. It is theorised that pulp fibres present in the mixture could adsorb the polysaccharides that would otherwise keep the colloidal system electrostatically stable. This destabilisation was most prominent at lower proportions of the stickies-free pulp suspensions used for mixing. These results show that care must be taken when mixing different pulps for paper and board production, as even a small amount of replacement pulp can lead to destabilisation of DCM and formation of deposits. Furthermore, special care must be taken when mixtures of pulps are used to validate stickies measurements. [ABSTRACT FROM AUTHOR]

The activation parameter developed is based on the fiber wall thickness distribution, fiber curl distribution, and water retention value of the unrefined fibers. The mechanical properties of paper that contain chemical pulp depend, among other things, on the free fiber segment activation between fiber-fiber crossings that is created during drying. Experimental data revealed that the degree of fiber swelling is responsible together with the fiber shape factor (curl) and fiber wall thickness for the extent of fiber network activation. The amount of bonding between fibers also affects fiber segment activation. Based on the experimental data, it was deduced that interfiber bonding ability of fibers, characterized as the water retention value, was mainly responsible for the development of handsheet density. Tensile index development was more affected by the morphology of fibers, which was the main determinant for high activation potential of fibers. Factor analysis was used to identify the main causes of variation for a refining data set of 20 Eucalyptus grandis samples. Three independent descriptors were found to be responsible for the majority of the variation: the bonding and activation factor, the factor of microcompressions, and the factor of fiber wall thickness and fiber curl. The activation parameter developed in this study can be used to determine the effect of fiber segment activation and inter-fiber bonding on the inplane mechanical properties of paper. [ABSTRACT FROM AUTHOR]

The article focuses on the prediction of the tensile breaking strength, the most commonly used physical property for paper characterization. It develops a novel three-dimensional computational simulator of paper structure to better understand the influence of fiber morphology on paper properties. It also discusses the development of the tensile strength model.

The purpose of this investigation was to study the effect of fiber characteristics, especially fiber wall thickness, on the hygroexpansion behavior of paper due to humidity changes. Five different eucalyptus Kraft pulp samples were studied with an OPTIDIM hygroexpansivity tester. As a reference, birch and acacia were included. In all, seven pulp samples were refined at low consistency (LC), using a Voith Sulzer refiner. Both anisotropic and isotropic sheets were investigated. The sheets were dried under restraint. The results showed that fiber wall thickness is an important factor in controlling the hygroexpansivity of paper through fiber network activation. [ABSTRACT FROM AUTHOR]

The retention behavior of polymers having the specific affinities of glycohydrolases for pulp fibers was investigated with regard to paper-strength enhancement in contaminated papermaking systems. Carbohydratebinding modules (CBMs) of cellulases derived from Trichoderma viride and T. reesei, and of xylanase from Thermomyces lanuginosus, were obtained by site-directed digestion with papain, then introduced into anionic polyacrylamide (A-PAM) via a peptide condensation reaction. Three types of CBM-conjugated A-PAMs (CBM-A-PAMs) displayed different retention behavior, depending on the kind of pulp substrates, i.e. hardwood and softwood fibers. The CBM-A-PAM from T. viride demonstrated good additive retention for hardwood pulp fibers, resulting in high tensile strength of paper sheets, even under contaminated conditions in the presence of Ca2+ ions and ligninsulfonate. The CBM-APAM from T. reesei showed better performance for softwood than for hardwood sheets. The xylanase CBM-A-PAM was preferentially retained on hardwood fibers in which hemicelluloses might be present. Such an additive retention system, with inherent affinities of enzymes for pulp fibers, is expected to expand the application range of CBM-polymers in practical wet-end processes. [ABSTRACT FROM AUTHOR]

In the field of sustainable design an important place occupies life cycle of printed products. One of the possibilities to increase the quality of the environment in this area arises from the selection of paper in the fiber type context, expenditures of water and energy and ink in relation to the share of renewable raw materials. In this paper the research results of chromatic characteristics of the fibers obtained by recycling prints made on different types of paper and with conventional and environmentally more favorable inks are presented. Influence of the composition of graphic materials and the dynamics of aging prints, which are processed by deinking flotation are discussed. The research results are scientific contribution in the field of deinking mechanism of aged prints and influence of graphic materials on the chromatic characteristics of the recycled fibers. Results are applicable in the field of sustainable product design and formulation of new materials. [ABSTRACT FROM AUTHOR]