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Abstract Focussing on the insulating material of power transformer—cellulose insulation paper, this paper first introduces the basic characteristics and engineering application background of insulation paper. Then, the research progress of improving the mechanical properties, thermal stability and electrical properties of insulation paper by nano modification in recent years is compared, and the promotion mechanism is analysed. In addition, in practical engineering application, the oil–paper composite insulation system composed of insulation paper and insulating oil is used for the internal insulation of oil immersed transformer. Therefore, the influence of modified insulation paper on the performance of oil–paper composite insulation system is analysed. Finally, the newly reported new insulation paper is introduced, and the future development trend of modification of traditional insulation paper is analysed.

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A composite filler was developed by pre-flocculation of fiber fines and precipitated calcium carbonate (PCC) particles with flocculants such as cationic polyacrylamide (cPAM) and bentonite. The composite filler was compared with a conventional loading method in terms of physical properties of handsheet and filler retention. The handsheets using the composite filler showed higher strength properties than that using a conventional loading at a similar paper ash content level, implying that paper ash content can be increased maintaining same level of paper strength. Optical properties such as opacity and brightness of the paper with the composite were quite similar with the paper with the conventional loading. Filler retention of the composite filler was slightly higher than that of the conventional loading even though retention aids were not used for the composite filler. Paper formation of the composite filler was better than the case of the conventional loading. However, the sheet with the composite filler showed lower bulk than that with the conventional loading. Conclusively, the composite filler technology by pre-flocculation of fines and filler has a potential to be utilized to produce a high loaded paper. [ABSTRACT FROM AUTHOR]

The dielectric properties of oil-paper insulation degrade due to moisture ingression and ageing. This degradation significantly impacts the space charge accumulation and charge trapping behaviour in the insulation, which are vital parameters for insulation health under the high-voltage direct current environment. In this work, an improved model based on the isothermal relaxation current (IRC) has been developed to study the charge trapping behaviour of an oil pressboard under the influence of moisture and ageing. The conventional IRC model considers the total relaxation current because of charge de-trapping only. However, in the case of a composite dielectric like oil pressboard, dipolar relaxation also affects the relaxation current. In this work, a methodology has been proposed to investigate charge de-trapping behaviour of oil-pressboard insulation considering the dipole relaxation process from IRC measurements. For this purpose, frequency domain spectroscopy measurements and IRC measurements have been performed on oil-impregnated pressboard specimens carefully prepared in the laboratory having different ageing conditions and moisture contents. Results presented in this work depict that charge trapping parameters, i.e. the trap depth and trapped charge distribution are highly affected both by ageing and moisture. It was observed that ageing leads to the generation of deeper traps, while moisture mainly enhances the density of shallow traps.

ABSTRACT: Conventional cellulosic paper, rendered electro‐conductive, may hold considerable promise for diversified applications in such areas as electro‐magnetic interference shielding and energy storage. Here, an electro‐conductive cellulosic paper was prepared by surface application of multi‐walled carbon nanotubes (MWCNTs)/polyaniline (PANI) nanocomposites onto a conventional base paper. MWCNTs/PANI nanocomposites were prepared by in situ polymerization of aniline with different contents of MWCNTs and used as electro‐conductive filler for the fabrication of electro‐conductive surface‐coated paper. The achieved MWCNTs/PANI nanocomposites exhibited a core‐shell structure, as evidenced by TEM. Effects of feeding ratios of MWCNTs on the rheological behavior of nanocomposite coatings, as well as the mechanical properties and electrical conductivity of surface‐coated paper were studied. Results revealed that the rheological behavior of the nanocomposite coatings showed strong dependence on the MWCNTs content. Moreover, both the electro‐conductivity and mechanical properties of surface‐coated paper were improved as a function of surface application of MWCNTs/PANI nanocomposites, particularly, in presence of an optimum content of MWCNTs. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46329. [ABSTRACT FROM AUTHOR]

The moisture-induced degradations during the use of paper are of growing concern for the existing paper materials stored in libraries, archives and museums. Knowing the moisture profiles is therefore a primary step in order to understand paper deterioration and give an assessment of degradation rate of library collections in their preservation. In this paper, the theoretical models based on 2-D scanning electron microscope real image microstructure were established for describing moisture transport in paper sheet in response with external humidity and the moisture diffusion profiles. The acid-catalyzed hydrolysis kinetic in combination with moisture diffusion theory gave the complementary explanation for the time-dependent natural aging process of a paper sheet and book stacks. The differential equations were solved by a numerical approach based on the finite element method implemented in commercial COMSOL Multiphysics. The 2-D simulation results, with a mesh based directly on SEM characterization of microstructure, could show the equilibrium moisture contents and the degradation rates as a function of relative humidity in cellulose pores and cellulose fibers across the transverse section of paper. For the stacks composed of books, the air gaps between the books provided convenient channels for diffusion and transport, accelerating the moisture transport process in the book stacks. [ABSTRACT FROM AUTHOR]

High-density polyethylene (HDPE), bagasse fibers treated by four pulping processes (AS-AQ (alkaline sulfite anthraquinone), SODA-AQ (soda anthraquinone), MEA (monoethanolamine) and chemical–mechanical pulping (CMP)), three levels of nano-SiO2(0, 2, and 5 wt%), and maleic anhydride polyethylene as coupling agent were used to produce pulp–plastic composites (PPCs) by injection molding. The physical and mechanical properties of corresponding composites were evaluated according to ASTM standards. The results showed that compared to untreated bagasse/HDPE composite, the addition of bagasse pulp fibers increased significantly the mechanical properties such as tensile strength and modulus, flexural strength and modulus, and hardness. The chemical pulps-reinforced composites showed better mechanical strengths than that of CMP-reinforced composites, but in some properties, CMP pulp composites have comparable results to the chemical pulp-reinforced composites. Natural fibers (untreated and treated) increased water absorption and thickness swelling of composites compared to pure HDPE. The addition of nano-SiO2particles showed both increasing and decreasing trends on physical and mechanical properties ofPPCs. [ABSTRACT FROM PUBLISHER]

Natural fibers are gaining much interest in composite materials because of their potential to replace conventional glass fibers. In particular, unidirectional flax fiber composites have shown excellent mechanical properties with different thermoset matrices. However, few data are available when they are made with a biodegradable thermoplastic matrix. This paper compares the mechanical properties of two types of unidirectional flax composites using polylactic acid as the matrix: one made with layers of aligned flax rovings alone and the other containing an additional paper layer fabricated using paper making techniques. The results show that specific tensile properties of the flax/PLA (252 MPa·cm 3 ·g −1 ) and flax-paper/PLA (217 MPa·cm 3 ·g −1 ) composites are similar to those made using woven glass fabrics impregnated with epoxy (227–278 MPa·cm 3 ·g −1 ). Very high impact strength (600 J/m) was also obtained for UD flax-paper composites compared to unreinforced resin (15 J/m). Together these mechanical properties are promising for industrial applications of this new reinforcement. [ABSTRACT FROM AUTHOR]

A kind of paper-based composite was prepared with short carbon fibers (CFs) and para-aramid fibrids through the process of papermaking. The dielectric properties of the paper-based composites at microwave frequency were investigated. Based on the Lichtenecker Rule, the dielectric constants of CFs in composites at different CF concentrations were calculated. The absorbing performances of paper-based composites were calculated from the test results of electromagnetic parameters. It was shown that for the composites loaded with 1 mm CFs, the real part of complex permittivity rises at first then tends to be stable with the increase of the CF content, and the imaginary part rises at first then falls slightly, while for composites loaded with 3 or 6 mm CFs, both the real and imaginary part of complex permittivity grows at first and then falls rapidly with the CF content increasing. When the CF content is below 10 wt%, the composites containing longer CFs have larger permittivity at the same concentration. The Lichtenecker Rule is found to be not suitable for the system studied in this paper, especially when the content of CFs is high. The variations of reflectance and absorbance with the content of CFs generally have analogous trends . It is also found that to achieve better absorbing performance, the length and content of CFs together with the thickness of composites should be considered. In this study, the lowest reflection loss at 10 GHz reaches –27.59 dB when the paper-based composite is loaded with 1 mm CFs at the concentration of 10 wt% and the optimum thickness of 1.84 mm. [ABSTRACT FROM AUTHOR]

Cellulose nanofibers have been showing much greater potential to enhance the mechanical and physical properties of polymer-based composite materials. The purpose of this study is to extract the cellulose nanofibers from waste bio-resources; such as waste newspaper and paper sludge. The cellulosic raw materials were treated chemically and physically in order to extract individualized cellulose nanofiber. The combination of acid hydrolysis and following mechanical treatment resulted in the extraction of cellulose nanofibers having diameter of about 40 nm. In order to examine the reinforcing effect of the extracted cellulose nanofibers, fully biodegradable green nanocomposites were fabricated by composing polyvinyl alcohol (PVA) resin with the extracted cellulose nanofibers, and then the tensile tests were conducted. The results showed that the enhancement in mechanical properties was successfully obtained in the cellulose nanofiber/PVA green nanocomposites. [ABSTRACT FROM AUTHOR]

Short carbon fibers (SCF) were modified with oxidation and coupling treatment to improve their water-wettability and bonding properties. Four types of dispersants were studied and discussed. Short carbon fibers/plant fiber (PF) composite papers were prepared by papermaking techniques. Scanning electron microscopy (SEM) and tests to determine zeta potential, absorbance, tensile index, and conductivity were carried out to investigate the modified effect of SCF and the interfacial properties. Modification experimental results showed that the surface grooves were deepened and new superficial grooves were generated by the liquid acid oxidation. The reaction with the silane coupling agent provided higher density and more uniform distribution on the SCF surface than that of organic titanate, and it obviously increased the roughness and the absolute value of zeta potential. After modification, the hydrophilic properties and dispersion in aqueous solutions were improved, the SCFs could form a good mechanical grip with plant fibers, and the conductivity and physical strength of SCF/PF composite papers were enhanced. It was shown that there was obvious adhesive binding at the fiber overlap nodes by the SEM analysis. It was confirmed that the improvement of physical properties of composite paper can be ascribed to the interfacial enhancement. [ABSTRACT FROM AUTHOR]

The effect of nanosilica particles on the water resistance of a polyurethane/nanosilica composite coated paper substrate was investigated. The polyurethane/nanosilica composite coating was prepared by dispersing nanosilica powder into solvent-based polyurethane using high mechanical stirring force. Paper substrate was coated with polyurethane/nanosilica composite using a Rod Mayer technique. Various compositions of polyurethane/nanosilica composite coatings on paper substrate were prepared. The total thickness of the paper coated with polyurethane/nanosilica composite was 0·3 mm. The field emission scanning electron microscopy images indicated that the presence of nanosilica has improved the surface roughness and porosity of paper substrate. The addition of nanosilica in polyurethane coating had increased the water resistance ability of the coated paper. It was demonstrated that polyurethane/nanosilica-6% shows better water resistance and exhibits better thermal stability than the nanocomposites with lower nanosilica loading. Fourier transform infrared spectroscopy result shows that there was no chemical reaction between nanosilica and polyurethane. [ABSTRACT FROM AUTHOR]

This paper examines the main physical and mechanical properties of aged and non-aged polymer composites made of a matrix filled with 10 % fiberized or chopped old newspaper oxo-degradable into polypropylene. The impact of the modification of the filler with a polyvinyl acetate water dispersion and with carboxymethyl cellulose on the properties of the extruded flat foil made of composites was studied. Adding a lignocellulose filler worsens the properties of the products obtained, but significantly accelerates the degradation of the composite material. The used filler modifiers improve the examined physical and mechanical properties, but increase the weather resistance of the foil products. [ABSTRACT FROM AUTHOR]

Highlights: [•] We deposited multi-wall carbon nanotubes on carbon fiber paper with a simple CVD. [•] We investigated the inherent mechanism of Ni particle's self-dispersion. [•] The MWCNTs/CFP composite possesses wonderful electrical conductivity. [ABSTRACT FROM AUTHOR]

Inorganicfillers, the second largest component of the papermakingprocess, have poor bondability with cellulosic fibers, interfere ininterfiber bonding, and reduce paper strength. Filler preflocculation/modificationis a practical method for enhancing interactions between the fillerparticles and fibers. This article reports on the effects of fillercontent and preflocculation on the filler bondability factor calculatedbased on first-pass ash retention and paper strength properties suchas the tensile, Z-direction tensile, and compositetensile indexes. Talc filler preflocculated using 0.1–0.8%dosages of cooked cationic starch based on the dry weight of fillerwas loaded in paper to obtain varying filler contents of 15–24%.The filler bondability factor (FBF) and various tensile propertiesof paper were calculated and analyzed for all experiments. FBF andpaper strength were reduced with increasing filler content in paper,whereas they were improved upon addition of preflocculated fillerin paper. Noticeably, preflocculated filler resulted in increasesin FBF and composite tensile index of 13–24% and 7–15%,respectively, at a 24% filler content in paper. [ABSTRACT FROM AUTHOR]

ABSTRACT A novel strategy via paper as an effective substrate has been introduced as a thermoelectric material in this work. Free-standing poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/paper composite films are conveniently prepared by a one-step method of directly writing PEDOT:PSS solution on paper, making the process simple, rapid, and facile. The free-standing composite films display excellent flexibility, light weight, soaking stability in water, and great potential in large-scale production. Improved thermoelectric properties are obtained in PEDOT:PSS/paper composite films, owing to the simultaneously enhanced Seebeck coefficient (30.6 μV K−1) and electrical conductivity, and a low thermal conductivity (0.16 W m−1 K−1) compared with pristine PEDOT:PSS films. The results indicate that paper as an effective substrate is suitable for the preparation of high-performance and flexible thermoelectric materials. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 737-742 [ABSTRACT FROM AUTHOR]

Abstract: Natural continuous bast fibres (hemp, flax, etc.) are gaining popularity in composite materials because they can advantageously replace glass fibres. It is found that intrinsic properties of unidirectional (UD) composites are almost equivalent to those of unidirectional glass fibre composites. Unfortunately it is difficult to get repeatable results because of the inherent variability in the properties of bast fibres compared to glass fibres. Their quality is largely affected by the weather conditions, the extraction location along the plant and the techniques used to extract them (retting, bleaching, etc.). In this work, unidirectional hemp/paper/epoxy and flax/paper/epoxy composites are manufactured by adding one or two sheets of paper at the surface of a unidirectional layer of hemp or flax fibres before molding. The composites are tested under tensile loads and the results compared with those obtained for UD composites made without paper. The results show a significant increase in strength and modulus repeatability when the paper layer is present. A significant increase in strength and modulus was also obtained compared to the base epoxy properties. The resin permeability of the flax–paper reinforcement has also been evaluated and compared to that of a standard glass fabric. Globally, the results suggest that adding thin sheets of paper at the surface of reinforcement layers stabilizes and increases the composite strength but slightly reduces the Young’s modulus. However the permeability of the flax–paper reinforcement was much lower than that of the glass fabric. Modifications to the paper architecture will be required to improve this aspect. [Copyright &y& Elsevier]

The influence of temperature and relative humidity on the moisture content of paper honeycomb sandwich panels was studied, and the ideal three-dimensional diagram between the moisture content of paper honeycomb sandwich panels and the temperature and relative humidity was constructed by the GAB model. The evaluation equation of critical stress and plateau stress were obtained. The results indicate that the moisture content of paper honeycomb sandwich panels rises with the increase of relative humidity and declines with the increase of temperature; as the moisture content increases, the critical stress and plateau stress of paper honeycomb sandwich panels decline linearly; with the increase of the moisture content, the energy absorption of paper honeycomb sandwich panels increased firstly and then decreased; the evaluation equation of critical stress and plateau stress can predict the mechanical properties of paper honeycomb sandwich panels in different temperatures and relative humidities. [ABSTRACT FROM AUTHOR]

Paper and prints on it are analyzed as composite materials. Printing, varnishing and lamination are described in terms of the formation of the composite material. The article discusses why and how the properties of a print should differ from the properties of paper. [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]

Novel sandwich composites made of syntactic foam core and paper skin were developed as potential building materials. Interface bonding between core and skin was controlled by varying starch content. Two different microsphere size groups were employed for syntactic foam core manufacturing based on the pre-mold processing method. Properties of skin paper with starch adhesive on were found to be affected by drying time of starch adhesive. Mechanical behavior of manufactured sandwich composites in relation with properties of constituent materials was studied. Skin paper contributed to increase up to 40% in estimated flexural strength over syntactic foams, depending on starch content in adhesive between syntactic foam core and paper skin. Small microsphere size group for syntactic foam core was found to be advantageous in strengthening of sandwich composites for a given starch content in adhesive. This finding was in agreement with calculated values of estimated shear stress at interface between skin and core. Failure process of the sandwich composites was discussed in relation with load–deflection curves. Cracking of syntactic foam core was detected to be the first event in sandwich composite failure sequence. Hygroscopic behavior of syntactic foam panels was investigated. Moisture content in the foam was measured to be high for high starch content in the foam panels. No significant moisture effect on flexural strength of syntactic foam panels after being subjected to moisture about 2 months was found for both microsphere size groups. However, substantial decrease (28%) in flexural modulus was found for the foam panels made of large microspheres although not much moisture effect was found on that of small microspheres. [ABSTRACT FROM PUBLISHER]

This article describes a facile method for the preparation of cellulosic catalyst paper: the in situ synthesis of gold nanoparticles (AuNPs) on zinc oxide (ZnO) whiskers, the preferential support for AuNPs, preloaded into a paper matrix. The ZnO paper composites were fabricated using a high-speed and low-cost paper-making technique, and immersed in an aqueous solution of HAuCl4. After drying, fine 5 nm AuNPs were successfully formed on the ZnO whiskers inside the paper matrix. As- prepared AuNPs@ZnO whisker-containing paper (AuNPs@ZnO paper) is similar to ordinary paper products, being flexible, lightweight, and easy to handle. The AuNPs@ZnO paper exhibited a high catalytic efficiency towards the reduction of 4-nitrophenol to 4-aminophenol in aqueous media. Furthermore, the addition of a polyamideamine epichlorohydrin resin provided a wet strength to the AuNPs@ZnO paper, which enables several catalyst recycles with no significant losses in catalytic activity. [ABSTRACT FROM AUTHOR]

Abstract: This paper highlights an innovative model of waste management combined with poverty reduction, which has been developed by the organisation Waste for Life (wasteforlife.org) – a network of academics, students, practitioners and on the ground cooperative partners in low income communities. The Waste for Life teams work with local cooperatives to create waste-based composites, which may be sold in local markets, thereby creating an income stream. The application of this model to the context of cartoneros (waste picker) cooperatives in Buenos Aires, Argentina, reveals that viable products can be made from paper and plastic waste, with low-impact material preparation that circumvents the need for chemically intensive, polluting and mechanically degrading procedures, preserving recycled fibre integrity. Tests on material samples indicate mechanical properties comparable to products made with more complex processing. The production model is based on the philosophy that not only the waste materials, but also the production equipment should be locally sourced and manufactured and products created to suit local markets. A simple reproducible model has been developed for the local manufacture of composites from waste, which can provide an income source for waste pickers as well as providing an innovative waste management solution. [Copyright &y& Elsevier]

Wood and cellulose derivatives, in both fibrous and water-soluble macromolecular form, are emerging as outstanding candidates for organic electronics applications due to their large-scale availability, low cost, and easy processability. Paper and wood fibre-based derivatives are considered to be materials of choice as supports for communication world-wide. The interest in producing inexpensive and universally available conducting polymer/cellulose fibres substrates resides in the possibility of creating new materials that can be used for a broad range of advanced applications. For instance, PPy/cellulose fibres composites can be used for the preparation of energy storage devices thanks to the conjugation of the high specific area of cellulose fibres and the electrochemical properties of PPy. Other possible applications of such composites are in the area of the antistatic materials, sensors, electromagnetic interference shielding materials, smart packaging, and tissues. Concerning the woody polymers, some of them (i.e. cellulose derivatives) also exhibit biocompatibility, as well as film-forming properties and transparency. In combination with the electrical properties of PPy, these features make PPy/macromolecular cellulose composites suitable for applications as displays, lighting, and photovoltaics. Due to their chemical structure, macromolecular wood derivatives have been proposed with success as enhancing conductivity additives in Py polymerisation. The aim of the present review is to provide an overview of PPy chemistry and of the most relevant advances attained in the production of PPy/wood derived materials conducting composites. [ABSTRACT FROM AUTHOR]

Abstract: Environment-responsive membranes were prepared by coating filter paper with poly (N-vinylcaprolactam) hydrogel. These membranes could be made to switch between hydrophobic and hydrophilic states in a reversible manner by the addition or removal of lyotropic salts. The effects of polymer loading and salt concentration on hydraulic permeability and human immunoglobulin G (hIgG) binding property of these membranes were studied. A candidate membrane possessing high hydraulic permeability and hIgG binding property was selected for carrying out protein purification experiments. This membrane demonstrated selective antibody binding, and could be used for hIgG purification from simulated cell culture supernatant. [Copyright &y& Elsevier]

Abstract: The diffusion process of deuterated water (D2O) in washi (Japanese traditional paper) was investigated by means of a deuterium exchange method and Fourier-transform near-infrared (FT-NIR) transmission spectroscopy. The samples were the modern (AD 2003) hand-made washi and those from an archival collection of cultural artifacts (AD 1791 and 1615). Four absorption bands were identified in the NIR spectral range from 7200 to 6000cm−1 which are due to OH groups in the amorphous, semi-crystalline and two types of crystalline regions of cellulose. The accessibility of D2O increased with decreasing state of order of cellulose, and the saturation accessibility increased with the age of the samples. It was suggested that during aging hemicellulose, which forms a composite with cellulose in paper, was progressively hydrolyzed, resulting in the expansion of inter-molecular distance between cellulose chains. The oldest sample showed a low diffusion rate compared with the others. SEM observation of the textile structures indicated that the oldest sample had two layers due to beating. It was estimated that the tight surface layer blocked the diffusant in the initial stage of the diffusion process. [Copyright &y& Elsevier]

The effects of partial or complete replacement of two commercial fillers, carbon black (CB) and silica on cure characteristics, tensile properties, fatigue life, morphological properties, and rubber-filler interaction of paper sludge (PS) filled natural rubber composites were elucidated. Compounding was carried out on a two-roll mill with total filler loading of 30 phr. Results indicate that maximum torque, tensile strength, elongation at break, tensile modulus, and fatigue life increased the cure time while the scorch time decrease with increasing carbon black loading ratio of PS/CB filled natural rubber composites. On the other hand, increased loading of silica in PS/silica weight ratio resulted in an increment in cure time, scorch time, maximum torque, elongation at break, and fatigue life but not significantly altering tensile strength and tensile modulus of the natural rubber composites. In addition, PS/silica filled natural rubber composites exhibit lower maximum torque, tensile properties, and fatigue life compared to the PS/CB filled natural rubber composites. Rubber-filler interaction and SEM micrograph studies proved that the higher interaction between carbon black and natural rubber occurred in PS/CB filled natural rubber composites rather than PS/silica filled natural rubber composites. [ABSTRACT FROM AUTHOR]

The article presents a study which investigated the mechanism of foaming with a combination of high-speed photography, scanning electron microscopy, and infrared thermography using foamed paperboard of different compositions prepared both in the laboratory and on a commercial machine. The study addresses the fundamental mechanism of foaming and identify the characteristics of the board that lead to a product with evenly distributed bubbles of a uniform size. The study attempts to understand the fundamental mechanism of foaming on paper-polymer composites.

Abstract: In this study, a computational micromechanics material model for the unloading behavior of paper and other nonwoven materials is presented. The asymptotic fiber and bond (AFB) model for paper elastic–plastic behavior [Sinha, S.K., Perkins, R.W., 1995. Micromechanics constitutive model for use in finite element analysis, In: Proceedings of the 1995, Joint ASME Applied Mechanics and Materials Summer Meeting, Los Angeles, CA, USA, Jun 28–30, 1995] has been extended to model the unloading process through a computational algorithm and implemented using the UMAT subroutine in ABAQUS finite element code. For every unloading increment, the material model assumes elastic unloading with a slope equal to the initial elastic modulus. The Jacobian matrix of the constitutive model is updated at every unloading increment by applying the incremental form of AFB model for a planar element with an elastic fiber and bond condition. A uniaxial tensile and a biaxial Mullen burst loading–unloading experiments were carried out for a paperboard sample and simulated using the model. The stress–strain curve and residual strain for the uniaxial loading were in good agreement with experimental results. The finite element model of the burst test with the AFB unloading material model predicted the general shape of the pressure versus deflection curve. However, the model over predicted the residual deflection by more than 50%. The loading portion of the pressure–deflection curve had a significant offset from experimental curves, and the nonlinearity in the unloading curve towards the end was not predicted. The discrepancies with experimental results are attributed to the burst test itself, model parameter estimation inadequacies, boundary conditions used in the FEA, and neglecting time-dependant effects. Nevertheless, the model can be useful in parametric studies relating microstructure to unloading behavior in structural problems. [Copyright &y& Elsevier]

Abstract: A porcelain body traditionally used to produce ceramic art and design objects was re-formulated using additional waste paper. The aim of this study was to develop knowledge into the technological properties of paper-composite porcelain in its green state, for use within the traditional practices of ceramic art and design production. Characterisation was made by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Two different production methods used by potters, slip casting and free-hand pressing, were used. The presence of the paper fibre, the paper type and the content amount are the important factors in strengthening development. Significant differences were found in relation to the content amount of paper fibre, between the mother porcelain body and the different content amount of paper fibre in the paper-composite porcelain body. [Copyright &y& Elsevier]

The basic types of polymer composite materials (PCMM) made from different kinds of reinforcing fibre fillers: short-cut fibres, paper, yarns, tow, sliver, fabrics, and nonwovens, and their properties and use are examined. Information on the fabrication and properties of the different kinds of composites are reported: extruded fibre plastics, getinaxes, textolites, unidirectional composites, honeycomb plastics, and others. New kinds of composites with ultrahigh mechanical and thermal characteristics are also examined. Some of the reported information was previously covered very sparely in the literature. Based on the examination, the features of polymer fibre composites are summarized in comparison to other materials, and they can be summarized as the following basic points: 1) combining different kinds of fibre fillers and matrices (binders) allows fabricating PCM with a wide range of properties by selecting the optimum indexes for articles with a broad spectrum of applications; 2) articles made of fibre PCM are not very materials-intensive and are technologically effective for processing in comparison to many traditional materials, metals and ceramics in particular; 3) with respect to the specific mass characteristics, fibre PCM can be many times superior to articles made of traditional materials—metals, etc., so that the mass (weight) characteristics of articles made of fibre composites can be significantly reduced, which is especially important for using them in vehicles, aircraft, rescue equipment, and sporting goods; 4) articles made of composites have high performance reliability, are almost immune to corrosion, and do not require special protection or periodic painting of the surface. Due to the features of the properties and use, fibre PCM have a great future in the most varied areas of application. [ABSTRACT FROM AUTHOR]

Abstract: Conducting polymers have generated a great deal of interest because of their physical and chemical properties as well as their potential in industrially useful materials. However, one of the shortcomings of most conducting polymers is that they are often formed as intractable films that are difficult to process [1]. To overcome this problem we have incorporated various conducting polymers into sheets of paper in order to create new composite materials which combine the universal properties of a paper sheet or paper products with the chemical and electrically conducting properties of the conducting polymer. Various composite paper – conducting polymer products have been prepared by polymerizing polypyrrole and polyaniline directly onto the paper sheet using ferric chloride as the oxidant. Electronmicroscopy shows that the polymers comprise spheres of about 50–150 nanometers in size fused together such that they fully encapsulate the individual cellulose fibres in the paper sheet. The open matrix of fibres characteristic of the original paper sheet is maintained and hence provides a much greater specific surface area for the conducting polymer than that of a continuous flat sheet which would be the case if the polymer simply formed a laminar coating on the paper surface. In the case of polyaniline, it was also possible to form a different morphology of the polymer comprising a mix of nano-size spheres, rods and plates using ammonium persulfate as the oxidant. Conductivities of up to 6 Scm−1 have been measured for paper-polypyrrole composites and up to 2x10−3 Scm−1 for paper-polyaniline composites. [Copyright &y& Elsevier]

Abstract: Cellular structures currently applied in various engineering fields are mainly made of metals and papers. To engineering design textile composite cellular structures, in this paper, comparisons of various essential structural parameters affecting energy absorption and deformation are carried out. These parameters include the opening angle, the cell-wall length, the cell-wall thickness, the bonded cell-wall length, and the bonded cell-wall thickness. The structure geometries are created by in-house computer package which exports IGES files. Two-dimensional finite element analyses are conducted by MSC.Marc Mentat 2001 which imports these IGES files to numerical calculation. Orthotropic mechanical properties of the textile composite cellular structure laminate are applied for the finite element analyses. It is found that the opening angle, the cell-wall length and the cell-wall thickness affect significantly energy absorption and deformation. Strain energy density concentrations appear very seriously around the cell corners during quasi-static impact. [Copyright &y& Elsevier]

In this work, a number of handsheets made from unbeaten and unbleached kraft, refiner mechanical and cotton linter pulps and crack propagations on paper samples under monotonic loading, were analyzed and possible links with the properties of fibrous networks were investigated. Crack initiation and propagation on the tested paper strips were also investigated under a scanning electron microscope to determine visually the state of the paper matrix under applied loads. Furthermore, paper samples were subjected to a series of mechanical tests, such as tearing resistance, folding endurance and tensile strength. The primary goal of this study concentrated on determining the fatigue life responses of paper samples under cyclic loading. An empirical equation for the fatigue life responses of paper samples tested was developed. It was found that paper, being a heterogeneous composite material, responds differently to applied loads depending on the properties of its constituent individual fibers and the nature of interfiber bonding in its structure. Kraft handsheets, for instance, showed the highest mechanical properties, followed by samples made from refiner mechanical pulps and cotton linters respectively. Overall, the equation developed proved to be a good way of predicting the fatigue life of paper materials subjected to variable loads. [ABSTRACT FROM AUTHOR]

This paper presents a thorough study on the prediction of the elastic-material constants ratios of blended short-fiber yarns, based on the theory developed by the author for yarns of a single fiber type by considering the structures as transversely isotropic and combined with the techniques used in dealing with hybrid composite materials. The mean tensile strengths of the blended staple-fiber yarns are also predicted, with the exclusion of the statistical and hybrid effects, which will be dealt with in a separate paper because of their extreme complexity. The so-called minimum blend ratio, below which the mean yarn strength will not follow the rule of mixtures, and the critical blend ratio, below which the mean yarn strength will be weakened rather than strengthened owing to the addition of the reinforcing fibers, are calculated, and the variables involved are discussed. Finally, the effects of the breaking strains between the blending-fiber types on the yarn properties are investigated. All results are schematically illustrated and the necessary parametric studies are provided. [ABSTRACT FROM AUTHOR]