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Free-standing flexible supercapacitive electrodes have practical application for wearable energy storage devices. In this paper, graphene paper (GP), a flexible electrode substrate, was prepared by one-step reduction of graphene oxide (GO) using HI solution. GP can be used independently as a flexible electrode with specific capacitance of 227 F/g. In order to make up for the shortage of GP specific capacitance storage, polyaniline (PANI) with high specific capacitance and good electrical conductivity was selected to composite with GP by electrochemical polymerization approach. This method to fabricate electrode material by direct electrochemical polymerization avoids the use of conductive binder and organic solvent. Owing to the specific capacitance contribution of PANI and GP, the PANI/GP composites exhibit higher specific capacitance when the polymerization time is 30 s and the polymerization voltage is 0.8 V. At 1 A/g current density, the specific capacitance of composite is up to 759 F/g, which is 3.34 times of neat GP.

In recent years, the need for portable, low-cost, and eco-friendly devices for testing and monitoring has arisen. Paper-based devices have emerged as a response to these needs due to the properties induced by capillarity, flexibility, disposability, and biodegradability. In this work, the authors explored the possibility of tuning the hygro-mechanical response of paper-based cantilever beams using glycerol. A lumped-parameter model with non-linear stiffness is used to describe the dynamic response of the beams using three parameters. An experimental method based on resonance frequency tests is used to study the influence of glycerol on the dynamic response of four different beam configurations. The obtained results demonstrate that the resonance frequency of paper-based mechanical systems can be easily tuned by the imbibition of a glycerol–water solution. This study could lead to the development of tunable paper-based mechanical systems for specific applications such as energy harvesters and hygro-mechanical-based sensors.

Studies have shown that reinforced paper-based friction material with 600 µm carbon fiber length possesses a high dynamic friction coefficient but is subjected to abrasive wear during sliding contact. This work is devoted to further investigate the effect of operating variables on this friction material subjected to high operating conditions. A pin-on-disc test was carried out to determine the tribological behavior of this friction material sliding against 65Mn steel. The friction and wear rate results from measurements were discussed. The highest friction value of about 0.3 was obtained by varying the applied load at 120 N while the lowest friction value close to 0.02 was obtained when the sliding speed was 0.026 m/s. Increasing the sliding speed above 0.30 m/s caused constant temperature (175 °C) to fluctuate due to high friction heat generation on the sliding surface. The highest wear rate was 1.42 × 10−15m3/Nm by varying the sliding speed at 1.31 m/s. In contrast, the lowest wear rate was 2.1 × 10−16m3/Nm when the temperature was at 400 °C.

In paper-based microfluidics, the simplest devices are colorimetric, giving qualitative results. However, getting quantitative data can be quite a bit more difficult. Distance-based devices provide a user-friendly means of obtaining quantitative data without the need for any additional equipment, simply by using an included ruler or calibrated markings. This article details the development of a quantitative DNA detection device that utilizes the aggregation of polystyrene microspheres to affect the distance that microspheres wick through filter paper. The microspheres are conjugated to single-stranded DNA (ssDNA) oligomers that are partially complementary to a target strand and, in the presence of the target strand, form a three-strand complex, resulting in the formation of aggregates. The higher the concentration of the target strand, the larger the aggregate, and the shorter the distance wicked by the microspheres. This behavior was investigated across a wide range of target concentrations and under different incubation times to understand aggregate formation. The device was then used to successfully detect a target strand spiked in extracted plant DNA.

In this study, polyimide (PI) chopped fibers were modified by ethylenediamine, and PI paper-based composites were fabricated using the as-modified PI chopped fibers and para-aramid fibrids which served as raw materials through the wet-forming process. The influence of different alkali treatment durations on the properties of PI fibers and composites was investigated. In sharp contrast with the pristine PI fibers, there was a satisfying difference in modified PI fibers including rougher surfaces and improved wettability due to the introduction of hydrophilic groups as confirmed by scanning electron microscope and Fourier transform infrared spectrometer. With increase in the modification time, the tensile index, the tearing index, and the internal bond strength of the composites were improved by 40.6, 27.0, and 103.57%, respectively, due to the hydrogen bonds. Meanwhile, the dielectric strength of the composites increased by 77.2% compared with the unmodified ones. These remarkable changes were mainly attributed to the enhanced interfacial bonding of the composites and decreased porosity in the three-dimensional network structure of the paper. Moreover, thermal stability was kept preferably within a certain range in spite of slight decrease.

This article reports on the design, fabrication, and characterization of an in-pipe worm-like soft robot with pneumatic actuators based on origami paper-fabric composites in which the paper and fabric serve as the skeleton and skin of the robot, respectively. The robot is assembled with an extensor of a bellow-like structure for implementing peristaltic locomotion and a clamp fabricated using a Kresling crease pattern at each end of the robot for anchoring. The performances of the pneumatic actuators, as well as the worm robot, are characterized and their dependence on some material, structural, and pneumatic parameters are investigated. Stepwise inflation of the clamp actuator takes place as the pressurization duration increases. The extension ratio of the extensor has a nonlinear relationship with the pressurization duration. The higher rigidity of the paper with a high weight per unit area can facilitate faster retention near the end of the extension process for the extensor with a small number of creases, while it becomes a resistance for the extension of the extensor with a large number of creases. The softness, lightweight features, low cost, ease to fabricate, modular design, and mobility of the worm robot indicate it has potential to find application in pipeline inspection, etc.

It was found beneficial to manufacture bacterial cellulose (BC) obtained from waste food sources to create value-added packaging products by firstly performing purification and disintegration processing of the BC and then reinforcing it with paper pulp. The purification treatment involved using sodium hydroxide (2% w/v at 100°C for 1 h) on BC pulp to remove the bacterial protein and the resulting cultured medium film was characterized with respect to its physical properties. An acid treatment on the purified BC pulp was applied to disintegrate cellulose network before forming a film. The results showed that the sodium hydroxide treatment increased the film burst index and brightness. Heating the BC pulp to 70–100°C in 1.25–5.00% v/v sulfuric acid treatment for 30 min degraded the film’s mechanical properties. Also, a study of the addition and mixing of paper pulps or modified cationic starch to the BC was found to improve the film properties with respect to packaging properties. Inclusion of short fiber paper pulp by 30 wt.% created a good synergistic effect by improving the mechanical properties of film especially for tear strength. Moreover, cationic-modified cassava starch (2% w/w) improved the tensile and burst index as well as resistance to oxygen permeation of the BC film. The results indicate that the BC pulp could be used to improve mechanical properties and resistance to water vapor and oxygen permeation of the short fiber paper pulp film which is ideal for packaging materials.

Background Until now, environmental sustainability issues are almost entirely unsolved for packaging materials. With the final aim of finding materials with a single recycling channel, cellulose fiber/poly(vinyl)alcohol composites were investigated. Methods After extrusion and injection molding, samples of composite with different cellulose fiber content (30%, 50% and 70% w/w) were tested. Results Tensile mechanical tests exhibited an improvement in composite stiffness when the reinforcement content was increased together with a decrease in composite elongation. Solubility tests performed at room temperature and 45°C showed different behavior depending on the water-resistant film applied on the composite (50% cellulose fiber content). In particular, the uncoated composite showed complete solubility after 2 hours, whereas at the same time point, no solubility occurred when a non-water-soluble varnish was used. Conclusions The proposed composites, named Poly-paper, appear to warrant further investigation as highly sustainable packaging.

The behavior of a wet clutch during engagement is of great importance to the durability of the clutch and the drivability of a vehicle. While many different factors influence the engagement behavior, the focus of this paper is to investigate only one factor, the permeability of the wet clutch friction material. Two test cells for measuring the permeability of friction material mounted on clutch discs have been developed. The test cells were then used to examine the effect of clutch material ageing through clutch engagement on the permeability of the material. The tests were performed on full size friction discs including the steel core prior and subsequent to testing in a wet clutch engagement test rig. The ability of the friction material to allow for oil flow both through the sliding surface layer and the bulk of the material was measured. The results indicate that repeated clutch engagements will increase the bulk permeability. However, the repeated engagements will decrease the ability to pass fluid through the friction material sliding surface. This contradictory behavior could be explained by a combination of an increase in pore size through repeated compression and the surface glaze clogging of the friction interface surface pores.

Authentication devices transform cheap paper into legitimate documents. They are the sensory, informational, and computational features that make up valuable papers like banknotes and passports, and they provide the confidence required in moments of exchange and passage. These devices – which include techniques like watermarks and specialized threads, proprietary substrates and inks, or RFID chips – are the product of security printing, an industry that continuously reinvents the possibilities of paper. Importantly, these components protect paper things from counterfeiting, allowing it to function as an original and authentic copy and to do the logistical work of connecting quotidian materials to global networks. The value of valuable papers is therefore not purely extrinsic, socially or discursively established, but is also performed through its intrinsic material qualities. These are the authentication devices that are read, assessed, and trusted as paper things are circulated, and they are what securely connects paper to infrastructures of mobility.

This study introduces the opinion of the corrugation hierarchy to develop the second-order corrugation paperboard, and explore the deformation characteristics, yield strength, and energy absorbing capacity under out-of-plane static evenly compression loading by experimental and analytical approaches. On the basis of the inclined-straight strut elements of corrugation unit and plastic hinge lines, the yield and crushing strengths of corrugation unit were analyzed. This study shows that as the compressive stress increases, the second-order corrugation core layer is firstly crushed, and the first-order corrugation structures gradually compacted until the failure of entire structure. The corrugation type has an obvious influence on the yield strength of the corrugation sandwich panel, and the yield strength of B-flute corrugation sandwich panel is wholly higher than that of the C-flute structure. At the same compression rate, the flute type has a significant impact on energy absorption, and the C-flute second-order corrugation sandwich panel has better bearing capacity than the B-flute structure. The second-order corrugation sandwich panel has a better bearing capacity than the first-order structure. The static compression rate has little effect on the yield strength and deformation mode. However, with the increase of the static compression rate, the corrugation sandwich panel has a better cushioning energy absorption and material utilization rate.

The composite layered structures including paper corrugation, paper honeycomb and expandable polyethylene are innovative structures of cushioning energy absorption, and the compression and impact resistances of the expandable polyethylene can be enhanced by laminating the corrugated paperboard or honeycomb paperboard. This article evaluated the compression performance and cushioning energy absorption of the composite layered structures by the static compression and drop impact compression tests. On one hand, the static compression properties showed that the total energy absorption, energy absorption per unit volume and stroke efficiency of the composite layered structures were all higher than those of expandable polyethylene. The specific energy absorption was enhanced with the increase in compression strain but almost not affected by the compression rate. The specific energy absorption of the composite layered structures including the expandable polyethylene and honeycomb paperboard was greater than those of the expandable polyethylene and corrugated paperboard. The energy absorption efficiency of the composite layered structures including the expandable polyethylene and corrugated paperboard was large for the low compression stress level, yet that of the composite layered structures including the expandable polyethylene and honeycomb paperboard was large for the high compression stress level. On the other hand, the dynamic compression characteristics showed that the peak stress, energy absorption per unit area, energy absorption per unit volume and specific energy absorption of the composite layered structures embodying paper sandwich cores and expandable polyethylene had linear increasing trends with the increase of drop shock energy. At the same drop impact condition, the composite layered structures including the honeycomb paperboard and expandable polyethylene had better cushioning energy absorption, the peak stress decreased by 23.6% on average, the energy absorption efficiency raised by 8.85% on average and the specific energy absorption increased by 18.1% on average than those including the corrugated paperboard and expandable polyethylene. Therefore, the corrugated paperboard and honeycomb paperboard can helpfully improve the cushioning energy absorption of the expandable polyethylene, and the composite layered structures embodying the expandable polyethylene, corrugated paperboard and honeycomb paperboard may hold excellent packaging protection.

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.

Nanofiber has shown outstanding performance in many studies. Blending nanofibers into fibrous filter media is a promising way to improve the filtration performance. This paper discussed the modeling method for multi-fiber filter paper and the proper way to apply nanofiber into filter paper. Sixteen different filter papers were prepared and these filter papers covered the range of coarse-fiber-dominant and fine-fiber-dominant fibrous structure. The theoretical modeling method in this study for pressure drop and penetration of multi-fiber filter paper showed accurate results compared with the experiment data. It was found that for the higher quality factor, the nanofibers should be effectively separated by the coarse fibers. This study presented the idea of the fiber's effective contribution to filtration efficiency, which can lead to a comprehensive and distinct understanding of fibrous structure and filtration properties.

The vibration transmissibility of paper honeycomb sandwich plate was tested and the vibration transmissibility curve was simplified and characterized. Based on the basic principle of vibration mechanics, the equation for calculating the energy dissipated by damping of paper honeycomb sandwich plate-block system during vibration was deduced. Furthermore, the effects of honeycomb structural parameters (cell length, sandwich plate thickness) and block mass on the damping energy dissipation were analyzed. The results showed that the curves of vibration transmissibility for paper honeycomb sandwich plate can be divided into three regions: plateau region, amplification region, and attenuation region. The vibration transmissibility ratio in different regions can be expressed as functions of frequency. The energy dissipated by damping of paper honeycomb sandwich plate-block system depends on its vibration transmissibility. If the vibration transmissibility ratio–frequency curve is obtained, the damping energy dissipation of the system can be calculated. The total energy dissipation of paper honeycomb sandwich plate-block system during vibration is about equal to that of plateau region, and the energy dissipated in amplification and attenuation region can be neglected. Different honeycomb structural parameters have the same effect on the damping energy dissipation of the system. Block mass has little effect on the damping energy dissipation in plateau region and the total energy dissipation during vibration but has a greater impact on the energy dissipation in the amplification and attenuation regions. The purpose of this paper is to provide a basic method for calculation of energy dissipated by damping and evaluation of anti-vibration property for packaging material.

In view of cushioning energy absorption of paper composite sandwich structures with sinusoidal corrugation and hexagonal honeycomb cores, the static yield strength and compression deformation were firstly analyzed by experiments, then the unit volume energy absorption, unit area energy absorption, and specific energy absorption were evaluated. Further, the influences of static compression rate, corrugation types, and honeycomb thickness on the cushioning energy absorption were respectively studied. The experimental observations show that the paper composite sandwich structures are crushed layer by layer due to the difference in the yield strength of sandwiches, and the honeycomb core is crushed after the collapsing of corrugation core. The three evaluation indices of cushioning energy absorption have similar change rule with the compression rate, corrugation types, and honeycomb thickness. The influence of static compression rate on the yield strength and cushioning energy absorption of the paper composite sandwich structure is not obvious. The composite sandwich structures consisting of paper corrugation sandwich with large inertia moment and honeycomb sandwich with large thickness have more excellent cushioning energy absorption, the B-corrugation can increase the unit volume energy absorption of paper composite sandwich structures by up to 18% than C-corrugation, and the 3-honeycomb can increase the unit volume energy absorption of paper composite sandwich structures by up to 32% than 2-honeycomb.

Printing is not a new media technology, but it is continuously being renewed. In this sense, it is an example of novelty going largely unnoticed, woven into the quotidian and ordinary in unassuming ways. One reason for this is the incomplete way we tell the story of printed paper, which privileges narratives of readings, access, and dissemination. To complicate the way media scholars think printing, this article turns to the case of security printing, which produces objects like banknotes and passports that circulate with trust and authority. Here, printing emerges through the specific need to print securely, offering a narrative based on the need for order and protection. The work of security printing, always straddling between art and science, produces artefacts understood as authentic copies. Such a transformation of paper into valuable object relies on the technical artistry of the security printer, who sets the aesthetic and material standards of authenticity through physical features like watermarks, engravings, holographs, special substrates, threads, or inks. Drawing on a close reading of informational materials produced by the major actors of today’s security printing industry, this article explains how the need to print better than the (counterfeiting) competition fuels the need for novelty in the how of printing. It expands on three guiding principles that work in unison to keep printing on paper new: printing as material science, as complex composition, and as the display of matchless quality. Ultimately, this material quality of securely printed papers helps us think about the new in a way that is not tied up to the digital, so that security printing both complicates the way media scholars engage with printing and offers a reconsideration of the ways we categorize and theorize the differences between media ‘old’ and ‘new’.

This paper presents an investigation conducted on the development of banana fiber-reinforced paper pulp biocomposites. The investigations focus on parameters, such as fiber length, fiber volume fraction, and composite thickness, those affect the properties of the biocomposites. Regression models, using Box and Behnken experimental design, have been developed to predict acoustic performance of the biocomposite along with the analysis of these parameters. The correlation coefficient between observed and predicted values was found to be 0.95. The maximum Noise Reduction Coefficient is observed (through experimental) in the bulk density of 154 kg/m3 at frequency ranges between 250 Hz and 4000 Hz with the average value of 0.55.

One of the largest movers of the world economy is the oil and gas industry. The industry generates billions of barrels of oil to match more than half the world’s energy demands. Production of energy products at such a massive scale is supported by the equally massive oil and gas infrastructure sprawling around the globe. Especially characteristic of the industry are vast networks of pipelines that traverse tens of thousands of miles of land and sea to carry oil and gas from the deepest parts of the earth to faraway destinations. With such lengths come increased chances for damage, which can have disastrous consequences owing to the hazardous substances typically carried by pipelines. Subsea pipelines in particular face increased risk due to the typically harsher environments, the difficulty of accessing deepwater pipelines, and the possibility of sea currents spreading leaked oil across a wide area. The opportunity for research and engineering to overcome the challenge of subsea inspection and monitoring is tremendous and the progress in this area is continuously generating exciting new developments that may have far reaching benefits far outside of subsea pipeline inspection and monitoring. Thus, this review covers the most often used subsea inspection and monitoring technologies as well as their most recent developments and future trends.

This paper describes the possibility of the use of paper twines as core reinforcement in thermoset pultruded sandwich composites. Paper twines and glass fiber rovings were co-impregnated with polyester resin and co-pultruded to form sandwich rods. Pultruded sandwich rods were up to 26% lighter with regard to typical monolithic glass fiber reinforced polyester rods. The specific flexural strength and Young's modulus of the sandwich rods were up to 25% higher than those of monolithic glass fiber/polyester commercial rods. Thanks to its light weight and its availability as a continuous twine, paper twines may be used with great flexibility in pultrusion of sandwich structures. This may lead to up to 20–30% weight reduction and cost saving without losing flexural performance.

Waste paper-reinforced sodium alginate/carboxymethyl cellulose (NaCMC)-based bio-composite films were prepared by solution casting method by optimum combination of 1.5% sodium alginate and 1.5% NaCMC. The optimum combination was selected on the basis of good tensile strength and low moisture sensitivity. This film was further subjected to aqueous solution of potassium aluminium sulphate (potassium alum) to reduce water vapour permeability and moisture content. This potassium alum solution treatment further enhanced the mechanical and thermal properties, and the film biodegradability was not affected either due to the cross linking or colour addition, which has potential as a substitute for the currently used polyethylene-based films. Molecular interactions between polymers and potassium alum affected mechanical, thermal, and other properties and was confirmed by Fourier transform infrared spectroscopy, X-ray diffraction, energy dispersive X-ray, and thermo gravimetric analysis of the films. This bio-composite film may be suitable to replace non-biodegradable and costly biodegradable packaging materials.

The experimental values of Young's modulus for filter paper samples were obtained as a function of temperature. These experimental modulus values for the filter paper samples, along with literature modulus values for regenerated cellulose and chromatography paper, were used to derive equations that relate Young's modulus values of filter paper to the phosphorescence lifetimes of adsorbed phosphors on filter paper as a function of temperature. In addition, an equation was derived for one of the phosphors that relates the changes in phosphorescence quantum yield with temperature to Young's modulus. The basis for the equations is a theory for hydrogen-bond-dominated solids that considers Young's modulus as related to the average force constant for the hydrogen bonds in paper and the effective number of hydrogen bonds in paper. For all the systems investigated, linear relationships were obtained between ln(phosphorescence lifetime) and ln(Young's modulus). Also, a linear equation was obtained between ln(phosphorescence quantum yield) and ln(Young's modulus) for one of the phosphors. In general, the results of this work form the basis of a fundamental theory for the phosphorescence of compounds adsorbed on filter paper.

Air quality control has become increasingly important in many industrial areas. Glass fiber filter paper is widely used for the collection of airborne particulate matter. Since glass fiber is fragile, fiber dispersion is believed to be important for controlling filter paper properties. In this paper, the impact of fiber dispersion on filtration performance and tensile properties was studied. Two types of glass fiber filter paper prepared from six different dispersing methods were used to analyze the impact of dispersion on filtration and tensile properties. Rotational viscosity was used to characterize the fiber dispersion process. Dispersing strength and time had no significant effect on filtration properties, namely the pressure drop, penetration and figure of merit. The fiber composition should be the determining factor of filtration properties. Dispersing strength and time had little effect on the virgin tensile strength of glass fiber paper, while the tensile strength retention after folding was highly affected by dispersion. It is suggested that fiber cutting should be reduced in the fiber dispersion process for higher tensile strength retention.

Facial masks are beauty products which composed of a facial mask paper and beauty solution. Silk contains the amino acid structure closest to the human skin, and has the skin-friendly, cosmetic and antibacterial functions, but the common method for making nonwoven facial mask paper is not suitable for silk. In this paper, the silkworm’s spinning path is intervened manually to obtain a smart silk facial mask paper (SMC) of controllable thickness, so that the sericin on the silk fiber is well preserved. In the experiment where the SMC is compared with the nonwoven 384-cuprammonium rayon facial mask paper (CRMC) which is the most widely used in the market, it is found that the ways of forming the two facial mask paper are completely different, and therefore the morphologies under SEM are obviously different. The thickness of the SMC is 0.183 mm and the areal weight of it is 38.0 g/m2. It is very close to the CRMC (0.187 mm, 38.4 g/m2). The porosity of the SMC is 84.0%, which is slightly lower than that of the CRMC (86.3%), but its pores are well distributed. Compared with the CRMC, the smart SMC has higher dry and wet strength, lower elongation, slightly lower air permeability and liquid entrainment rate, and better antibacterial performance.

In the current scenario, the paperboard industries are experimenting the reinforcement of their products with various natural fibers. Based on affordability, low weight, biodegradability and recycl...

Water, oxygen, and air were investigated for their abilities to quench the room-temperature fluorescence (RTF) and room-temperature phosphorescence (RTP) of the protonated forms of benzo[f]quinoline (B[f]QH+) and benzo[h]quinoline (B[h]QH+), and α-naphthoflavone. As with earlier studies, H2O was found to be a more potent quencher of RTP than O2. However, both species were able to quench RTP. A simple method was developed for reporting the percentage decrease in RTP or RTF for a given quencher, and thus easy comparisons could be made among the component contributions to the overall quenching of the RTF and RTP signals. The RTP quenching data for the three phosphors were found to fit an equation of the form, Y = aXb. This equation allowed some conclusions to be made about the interactions responsible for the quenching of RTP by moisture. Also, it was found that RTF was much less sensitive to H2O and O2 quenching than was RTP.

Paper is a composite of fibers, air and additives where the fiber/fiber joints keep the network structure together. A study was undertaken to establish the link between the properties of the contact zone between fibers and paper performance under mechanical loading. The contact zone between fibers was investigated using light microscopy. A staining technique was developed for evaluating the influence of surface charge on fiber/fiber joint strength. The joint strength was linearly correlated with paper tensile strength and with the average amplitude of the acoustic events measured by acoustic emission testing. The fiber surface conformability was improved by changing the surface charge. This resulted in increased fiber/fiber joint strength as the relative contact area became larger. Increasing the molecular adhesion in the contact zone with the aid of strength additives also improved the fiber/fiber joint strength.

Porous carbon fiber papers, which are formed by randomly distributed carbon fibers, are commonly used as gas diffusion layers of proton exchange membrane fuel cells. Several key properties of the gas diffusion layers, for example, air permeability, thermal conductivity, and electrical resistance, are inevitably controlled by the strain it experienced, which is always a nonlinear function of the applied compressive stress. In the present study, a logarithmic-type constitutive model is proposed to characterize the nonlinear stress–strain relation of carbon fiber papers under compressive loading. A hexahedral configuration of carbon fibers is adopted as a typical microstructure of carbon fiber papers. Contact and bending deformation of carbon fibers are accounted for with use of Hertz’s contact model and beam bending model, respectively. The logarithmic-type constitutive model is eventually obtained by solving a differential equation considering the variation of structural porosity. The stress–strain curves of the present model and experimental data are compared for a number of commercial gas diffusion layer samples. The comparisons indicate that the present model is capable of predicting the mechanical performance of carbon fiber papers, and may be useful for analytical and numerical analysis of gas diffusion layers and fuel cells.

In this work, a study concerning the composition of Italian papers from the seventeenth to the twentieth centuries was carried out using energy dispersive X-ray fluorescence spectrometry (EDXRF), X-ray diffraction (XRD), and scanning electron microscopy coupled to energy dispersive spectrometry (SEM-EDS). The analyzed samples consisted of papers employed for drawing, writing, printing, and absorbance. Observations carried out by SEM magnified the typical paper morphology. EDXRF in combination with XRD and SEM-EDS allowed the determination of calcite, gypsum, kaolin, talc, magnesite, and dolomite, used as fillers in the production of the papers studied herein. The inks present in the handwritten and printed papers, investigated by SEM-EDS and μ-EDXRF, were synthetic, Fe based, and iron gall inks.

The effects of surface treatment of paper sludge (PS) with acrylic acid (esterification) and acetic acid (acetylation) on torque, stabilization torque, mechanical properties, water absorption, morphology, and thermal properties of PP/EPDM/PS composites were studied. It was found that esterified and acetylated composites exhibit higher stabilization torque than untreated composites. The esterification and acetylation treatment have improved the tensile strength, elongation at break, and Young's modulus but have reduced the water absorption of composites. The scanning electron microscopy (SEM) study of the tensile fracture surface of the esterified and acetylated composites indicates that the presence of acrylic acid and acetic acid increased the interfacial interaction between paper sludge and PP/EPDM matrix. The esterification and acetylation treatment also increase the thermal stability and crystallization of PP/EPDM/PS composites. It was found that paper sludge acts as a nucleation agent in the presence of acrylic acid and acetic acid.

The effect of paper sludge content and size on the processibility, mechanical properties, swelling behavior and morphology of PP-EPDM composites were examined. Results show that the increasing content of paper sludge in composites has increased the Young’s modulus and water absorption but decreased the tensile strength and elongation at break. At a similar filler content, PP-EPDM composites with the smallest size show the highest mechanical properties but the lowest water absorption resistance. SEM tensile fracture surface of composites show that the smallest size of paper sludge has better filler-matrix interaction than the larger size of paper sludge. Thermogravimetric analysis showed that the increase of paper sludge content has increased the thermal stability of PP-EPDM composites particularly at temperatures above 500 C.

This study investigates the effect of paper sludge’s mixing ratio and the types and concentrations of coupling agents on the physical and mechanical properties of paper sludge-thermoplastic polymer composites. In the experiment, four levels of mixing ratios of paper sludge to thermoplastic polymer (10: 90, 20: 80, 30: 70 and 40: 60) and three levels of coupling agent (Epolene G-3003TM) content (1, 3, and 5 wt.%) were designed to discuss the physical and mechanical properties of composite. Composite density, as expected, increased but melt flow index decreased when the paper sludge content increased. Thickness swelling and water absorption of composites was slightly improved by the addition of paper sludge compared with control specimens. Tensile properties of composites significantly increased as the mixing ratio of paper sludge increased. Especially, tensile modulus improved with the increase of paper sludge content. Flexural strength and modulus showed similar trends to that of the tensile properties. Notched and unnotched Izod impact strengths lowered by the addition of paper sludge. With the addition of coupling agent, G-3003TM, tensile and flexural properties improved considerably compared with control specimens (without any coupling agent). Epolene G-3003TM, with high molecular weight, was effective in the improvement of the composites’ tensile and flexural properties.

The effects of oxygen over a wide concentration range on the solid-matrix phosphorescence (SMP) of perdeuterated phenanthrene (D10) adsorbed on partially hydrophobic paper (1PS) were investigated. The SMP lifetime results of D10 adsorbed on Whatman 1PS paper and Whatman No. 1 paper were considered, and the SMP intensities and SMP lifetimes of D10 on 1PS paper were compared. The SMP quenching model employed showed that diffusional quenching was not very extensive for D10 adsorbed on both types of paper. In addition, a large fraction of the D10 phosphor molecules did not undergo diffusional quenching in either paper. The changes in the SMP intensities for D10 adsorbed on 1PS paper were much greater than the corresponding SMP lifetime changes, which indicated that static quenching by oxygen was very effective for D10 on 1PS paper. Also, the SMP intensity data indicated that a relatively large fraction of the D10 molecules were not quenched statically. The quenching data were interpreted and compared with equations that permitted both linear and nonlinear models to be employed.

Often hard implants undergo detachment from the host tissue due to inadequate biocompatibility and poor osteointegration. Changing surface chemistry and physical topography of the surface influences biocompatibility. At present, the understanding of biocompatibility of both virgin and modified surfaces of bioimplant materials is limited and a great deal of research is being dedicated to this aspect. In view of this, the current review casts new light on research related to the surface modification of biomaterials, especially materials for prosthetic applications. A brief overview of the major surface modification techniques has been presented, followed by an in-depth discussion on laser surface modifications that have been explored so far along with those that hold tremendous potential for bioimplant applications.

Poly(vinyl acetate) (PVAc) and vinyl acetate with butyl acrylate (VAc-BuA) copolymer latices are prepared by semicontinuous emulsion polymerization technique. The prepared latices are used in paper treatment using two different techniques. In the first technique, the latices are added during the paper sheet formation, but in the second one the untreated paper sheets are dipped in either the polymer or acetone polymer solution of different concentrations. The effect of different concentrations of the prepared emulsion latices by using different emulsifier and initiator concentrations on the paper sheet is studied. Increasing the initiator concentration in the preparation of PVAc latex decreases the retained polymer on the treated paper sheets. Also, increasing the butyl acrylate percentage in the copolymer latices improves the mechanical properties. The water uptake of the treated paper sheets is decreased by increasing the retained polymer. The effect of thermal treatment of the treated paper sheets is investigated.

Bleached wood pulp paper sheets were impregnated in a solution of methylene chloride containing different concentrations of vinyl acetate/vinyl chloride copolymer (2-6 gm/100 ml) for different time intervals (5-60 seconds). The effects of polymer concentration and dipping time on the retained polymer on paper sheets were determined. The effects of heating (softening) treated paper sheets at different temperatures [(100, 110, and 12000) for five minutes and at 110°C for different time intervals (3-15 minutes)] on the physical properties of paper sheets were also investigated. The physical properties of the impregnated paper sheets were highly improved. Breaking length increased from 2.2 to 5.4 km, burst factor increased from 12 to 38, tear factor increased from 64 to 105, and water absorbance decreased from 175 to 46. Softening temperature, heating time, and retained polymer play an important role in the improvement of the physical properties of paper sheets.

From the room-temperature fluorescence lifetimes of benzo(f)quinoline and 4-phenylphenol adsorbed on filter paper and earlier luminescence data, several photophysical parameters were calculated. Also, a number of equations that relate radiative and nonradiative rate constants to pre-exponential factors and activation energy terms were considered. By combining the luminescence data obtained in this work and previous luminescence data acquired as a function of temperature, it was possible to derive equations for the two model compounds that described fluorescence quantum yield and phosphorescence quantum yield as a function of the pre-exponential factors, activation energies, and temperature. These equations were somewhat complex, but some fundamental conclusions were revealed after a few simplifying assumptions were made.

A paper chromatographic study of the amino acid compositions of several histo logical fractions of wool has been conducted. The fractions considered were epicuticle, cortical cell membranes, paracortex, and regenerated oxidized keratin. Samples of these fractions were hydrolyzed with hydrochloric acid, and quantitative analyses of the amino acid content of these hydrolysates were accomplished through a modification of the standard two-dimensional paper chromatographic technique. The epicuticle was found to contain normal amounts of cystine but extraordinarily large quantities of aspartic acid and glutamic acid. In addition to confirming the results of the phosphotungstic acid analyses for cystine reported in a previous paper [14], the chromatographic studies of the paracortex showed large amounts of the basic and small amounts of the dicar boxylic amino acids to be present. The extremely low total of amino acid content found in the cortical cell membranes indicated the possible presence of some nonprotein constituent.

The manipulation of the physical characteristics of nonwovens and paper by variation of fiber and web geometry is briefly reviewed in terms of a new system of bonding in which the adhesive interfiber forces are a consequence of ionic chemical bonds. These bonds were created by the sequential covalent introduction of anionic sites onto the interior and exterior surfaces of microporous pulp and rayon fibers using a chloro-s-triazinyl fiber reactive dye and subsequent stoichiometric reaction with crosslinking polycations derived from ethylenimine. The tensile properties of both the pulp and rayon fiber assemblages were significantly augmented as a result of the development of both ionic inter- and intra-fiber bonds.

Seaweed fibre is usually discarded as biomass waste after extraction of useful ingredients from seaweed. However this seaweed fibre, a natural abundant cellulose material with uniform dimensions 10 times smaller than other plant-based fibre can be utilized as electrode material for energy storage. In this work, we converted seaweed fibre into conductive carbon electrodes by a thermal carbonisation method. The morphology, chemical composition and conductivity are highly influenced by the carbonisation temperature. In comparison to other biomass sources such as cotton pulp, seaweed fibre is finer, smoother and more conductive at low carbonisation temperature. These carbonized seaweeds were then used as a supercapacitor, giving a high supercapacitance (226.3 Fg−1) at the carbonisation temperature of 900°C, and good stability within 2400 cycles. This specific capacitance is significantly higher than values obtained from filter paper or cotton pulp.

When one end of a helically wound, laminated tube is free to rotate, axial loading alone will induce a torsional twist about the tube axis. This paper concerns an experimental investigation of this compressive deforma tion behavior of such tubes. Helically wound, laminated paper tubes serve to model the structure. The special apparatus used to accurately measure the free end rotation of the specimen is described. It is found that the total angle of twist reaches a critical value at roughly the same time that the axial compressive force achieves a maximum value at which the cylinder walls buckle by folding inward along the helical fiber lines of the tube. At the onset of buckling, the previously nonlinear and monotonically in creasing twisting rate changes rather abruptly to a constant value; thus, this effect further identifies collapse of the tube. Although the critical angle of twist increases with the tube length, for the short tubes studied here, there seems to be no apparent dependence of the critical load on the length. Empirical equations that relate the critical angle of twist and the subse quent uniform, post buckling twisting rate to the tube length are pre sented.

An experimental analysis was undertaken to establish the failure strengths in tension and compression along the strong direction (machine direction) and the weak transverse plane of isotropy (cross direction) for a typical paperboard. The principal strengths of the material along the strong machine direction and on the transverse plane which may be assumed to be approximately isotropic allowed the possibility of forming the elliptic paraboloid failure locus corresponding to this type of material. It was shown that papers in general are tension strong materials having the infinite part of their parabo loid failure surface turned toward the tension-tension-tension octant in the principal stress space.

The enzyme washing process is extensively applied in the industrial production of denim garments. The process parameters of enzyme washing have significant effects on washing performances and costs. Since the relationships between the process parameters and washing performances cannot be expressed explicitly, it is impractical to determine the process parameters to obtain the optimal production cost while satisfying requirements of customers intuitively. This paper proposes an optimization methodology by combining Kriging surrogate and differential evolution (DE) algorithm to address the production cost optimization of enzyme washing for indigo dyed cotton denim. First, an experiment using Taguchi L16 orthogonal array is conducted where temperature and concentration of cellulase enzyme are taken into consideration with processing time as the input parameters, while the washing performances (including color strength value, stiffness, and tensile strength in warp and weft directions of the washed denim fabrics) are the output responses. Second, the relationships between the inputs and outputs are established using the Kriging model. Third, the effects of the input parameters on the washing performances are analyzed, and the production cost optimization model is illustrated. Finally, a case study is given to depict the optimization process and a verification experiment is conducted to verify the effectiveness of the optimal values. On the whole, the proposed hybrid method, Kriging-DE, shows great capability of optimizing the production costs of the enzyme washing process for indigo dyed cotton denim.

This work aims to optimize the industrial extraction conditions of cellulose microfibers (CMFs) from Washingtonia palm fiber for application in starch bio-composite films. The CMF extraction was a mixed process that combines caustic soda treatment with hydrogen peroxide bleaching in a stirred thermostatic bath. To study the yield, whiteness index and α-cellulose content, three variables were selected; NaOH and H2O2 concentrations and treatment time. The optimum was determined using a Response Surface Methodology (RSM) approach for samples treated for 70 min with 5.21% NaOH and 5.54% H2O2. The optimized CMF was used to produce Starch/CMF bio-composite films with higher mechanical and barrier performance, which increased by 300% and 31%, respectively. Moreover, its moisture absorption and water solubility decreased by about 24% and 26%, respectively after adding 20 wt% CMF. In fact, morphological results showed that the higher CMF in the Starch/CMF20 leads to the heterogeneous CMF distribution and agglomerates resulting in weakened starch films. As a result, the extracted CMF can be a competitive nanofabrication filler.

Degumming is the dominant method for insolating lignocellulosic fibers in textile applications. Traditional alkaline degumming (TAL), as a common method, requires a high-concentration alkali and has been a severe challenge to the environment. In the research reported here, the possibility of innovative jute degumming by organic solvents 1-2 propylene glycol and a combination of additive green oxygen (GO-OS) was studied. The results revealed that fibers could be extracted by this system (under condition of 0.9% GO-OS, 180°C, 120 min), and obtained fibers with higher breaking tenacity (7.1 cN/dtex), yield (65.7%), breaking elongation (2.87%) and residual gum (11.7%), which all meet the requirement of the relevant Chinese Textile National Standards. Notably, the required reaction time (120 min) of the GO-OS system was 180 min shorter than that of the TAL method. Furthermore, the modifications introduced by the degumming effect on physicochemical aspects were characterized and confirmed by Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction. This study provides a promising degumming method for separating jute lignocellulose without acid and alkali consumption.

Coir fibre and pith are eco-friendly material used in the preparation of composites. Coir fibre and coir pith were treated with sodium hydroxide to study the effect of alkali for prolonged exposure on its properties. Fibre and pith were treated with different concentrations of NaOH from 5% to 30% for 24 hours at room temperature. Alkali treatment removes the impurities and the expose the crystalline cellulose and to enhance the surface properties. The alkali-treated coir fibre and pith were characterized by Scanning electron microscopy for morphology, X-ray diffraction for crystallinity index, thermogravimetry for thermal stability, Fourier-transform infrared spectroscopy for structural changes. The chemical composition was analysed for both fibre and pith. Physical properties such as bulk density, particle density and porosity were determined for pith. After alkali treatment, the properties (physical and chemical) of the treated fibre (5% to 20%) has been enhanced. For coir pith the properties has been diminished. Untreated/treated coir fibre/pith filter (CFP) were developed to study the removal of heavy metal ions from the waste water, where untreated (CFP) as a control. The removal efficiency of the developed CFP filter for heavy metal ions were determined by Inductively coupled plasma - optical emission spectrometry (ICP-OES). 5% CFP filter exhibited higher efficiency for removal of heavy metal ions.

A new source of natural dyes, which possessed antibacterial and UV protection properties, was proposed. Natural dyes were extracted from Fuji apple peel. The extract contained two anthocyanins and five quercetin glycosides. Silk and cotton fabrics were dyed using the extract with and without six types of mordants: Mg2+, Ca2+, Al3+, Ti4+, Fe3+, and Cu2+. The properties of the dyed fabrics were investigated by various means. The K/S values were used to show relative color strength of the dyed fabrics and the CIELAB color system was used to show the color hue of the dyed fabrics. The crystallinity of the silk was lower than that of the cotton. The silk was dyed deeper than the cotton regardless of the dyeing conditions, including dyeing temperature, dyeing period, and solution pH. This result comes from the existence of carboxyl and amino groups and low crystallinity of silk fibers. Fabrics with various colors, including pink, green, brown, and gray, were obtained by mordant dyeing. The dyed fabrics had splendid performance; that is, antibacterial and UV shielding properties. Color fastness to washing (color change) was comparably low but was enhanced with Ti4+ and Fe3+ mordants.