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Application of barrier dispersion coatings on paperboards, which must have proper moisture and grease resistance for food applications, has always been an interesting subject for the packaging industry. In this study, paperboards were coated with a novel dispersion barrier coating prepared through mixing soy protein isolate (SPI) and polyethylene wax (PE-wax). Different characterization methods were used to study the effects of coating and its composition on the physical, mechanical, and barrier characteristics of paperboards. The results indicated that the incorporation of PE-wax into the coating formulation caused significant reduction of the viscosity of coating slurries. It had no effect on the coating weight of the samples but increased the thickness of the coated paperboards as compared with those coated with SPI only. The increase of the wax content led to a reduction of 5-16% in the tensile strength values in comparison with the uncoated paperboards. Barrier characteristics, i.e., water vapor permeability (WVP), surface wettability, and water resistance, improved by adding PE-wax. In addition, it was found that there was a critical level for the addition of PE-wax, 50% of SPI, as no oil migration was detected when the paperboards coated with SPI coatings contained less than 50% PE-wax.

Insulation oil is an important dielectric in power devices, and many studies on mixed insulation oil have been conducted in recent years to improve the performance of insulation oils. To replace mineral oil directly, the authors previously developed a novel three-element mixed insulation oil successfully; the main parameters of which satisfy the IEC 60296-2012 standard for mineral oil. In the present study, the AC breakdown properties of insulation paper (pressboard) immersed by the new mixed oil and naphthenic mineral oil were compared. For both insulation oils, the increase in temperature cannot significantly reduce the breakdown strength of oil-immersed insulation paper (pressboard) at a low moisture content, and the increment of moisture content cannot reduce the breakdown voltage at a low temperature (25°C). The breakdown voltage decreases only when the two factors increase simultaneously. For the mixed and mineral oils, the AC breakdown voltage of oil-immersed paper (pressboard) with different thicknesses has significant difference. The mineral oil has a high breakdown voltage for the thin insulation paper, whereas the mixed oil has a high breakdown voltage when the thickness of the insulation paper (pressboard) exceeds 0.2 mm. This phenomenon is mainly caused by the breakdown field strength that varies with the increase of dielectric thickness and the different change trends of paper (pressboard) immersed with the mixed and the mineral oils. Moreover, the stack of thin multilayer insulation paper enables the mixed oil-immersed paper to have a higher breakdown strength than the mineral oil-immersed paper. For the AC breakdown voltage of oil-immersed pressboard with an oil-gap structure, the mixed oil is comprehensively superior to the mineral oil due to its larger relative permittivity.

In this study, the effect of air plasma on the surface properties of printed and coated cardboard was investigated. The material was activated by low-pressure cold plasma for 1, 10, 20, and 30 s. Wettability changes on the surface were examined by contact angle measurements using the sessile droplet technique. The differences in the surface free energy were calculated using the Lifshitz–van derWaals/acid–base and Contact Angle Hysteresis approaches. Optical profilometry was used for the surface roughness evaluation and an X-ray photoelectron spectroscopy analysis was performed to find changes in surface chemistry. Adhesive strength tests were carried out to estimate the adhesion changes after the material’s modification. It was found that the water and formamide contact angles increased after the plasma treatment while the diiodomethane contact angle did not change. As a result of the modification, the surface free energy also increased significantly and the surface roughness increased. The pull-off tests confirmed the improvement in the material’s surface properties. Moreover, it was demonstrated that the optimal effect can be obtained after just 10 s of the plasma process.

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.

In this study, the employment of the X-ray irradiation as bioremediation method to treat parchment has been deeply investigated. In particular, the effect of the irradiation doses on the structural stability of collagen, the main constituent of parchment, has been evaluated on a series of modern parchment samples by means of different opto-thermal and spectroscopic techniques in order to obtain the dose-dependent effect of irradiation on collagen. Moreover, the long-term behavior of the irradiated parchment has been considered by analyzing the same series of samples after being hygrothermally artificially aged. Characterizations by light transmission analysis, Fourier transform infrared spectroscopy and the ultraviolet–visible–near infrared (UV–Vis–NIR) reflectance one have been performed for the identification of the radio-induced effect on the parchment structure even in a dose range much wider than the need for sterilization. The obtained results have proved the safeness of the method in the short and long term confirming the applicability of this emerging procedure.

Funding Information: KSK and AB acknowledge funding by the UK Engineering and Physical Sciences Research Council (EPSRC) (EP/K014676/1). KSK also acknowledges Academy of Finland (Project number 310943). EK is grateful for the support by the FinnCERES Materials Bioeconomy Ecosystem. Funding Information: Open access funding provided by Aalto University. KSK and AB acknowledge funding by the UK Engineering and Physical Sciences Research Council (EPSRC) (EP/K014676/1). KSK also acknowledges Academy of Finland (Project number 310943). Publisher Copyright: © 2021, The Author(s). Copyright: Copyright 2021 Elsevier B.V., All rights reserved. Cellulose nanopapers provide diverse, strong and lightweight templates prepared entirely from sustainable raw materials, cellulose nanofibers (CNFs). Yet the strength of CNFs has not been fully capitalized in the resulting nanopapers and the relative influence of CNF strength, their bonding, and biological origin to nanopaper strength are unknown. Here, we show that basic principles from paper physics can be applied to CNF nanopapers to illuminate those relationships. Importantly, it appeared that ~ 200 MPa was the theoretical maximum for nanopapers with random fibril orientation. Furthermore, we demonstrate the contrast in tensile strength for nanopapers prepared from bacterial cellulose (BC) and wood-based nanofibrillated cellulose (NFC). Endemic amorphous polysaccharides (hemicelluloses) in NFC act as matrix in NFC nanopapers, strengthening the bonding between CNFs just like it improves the bonding between CNFs in the primary cell wall of plants. The conclusions apply to all composites containing non-wovenfiber mats as reinforcement.

This paper describes the use of fused deposition modeling (FDM) printing to fabricate paper-based analytical devices (PAD) with three-dimensional (3D) features, which is termed as 3D-PAD. Material depositions followed by heat reflow is a standard approach for the fabrication of PAD. Such devices are primarily two-dimensional (2D) and can hold only a limited amount of liquid samples in the device. This constraint can pose problems when the sample consists of organic solvents that have low interfacial energies with the hydrophobic barriers. To overcome this limitation, we developed a method to fabricate PAD integrated with 3D features (vertical walls as an example) by FDM 3D printing. 3D-PADs were fabricated using two types of thermoplastics. One thermoplastic had a low melting point that formed hydrophobic barriers upon penetration, and another thermoplastic had a high melting point that maintained 3D features on the filter paper without reflowing. We used polycaprolactone (PCL) for the former, and polylactic acid (PLA) for the latter. Both PCL and PLA were printed with FDM without gaps at the interface, and the resulting paper-based devices possessed hydrophobic barriers consisting of PCL seamlessly integrated with vertical features consisting of PLA. We validated the capability of 3D-PAD to hold 30 μL of solvents (ethanol, isopropyl alcohol, and acetone), all of which would not be retained on conventional PADs fabricated with solid wax printers. To highlight the importance of containing an increased amount of liquid samples, a colorimetric assay for the formation of dimethylglyoxime (DMG)-Ni (II) was demonstrated using two volumes (10 μL and 30 μL) of solvent-based dimethylglyoxime (DMG). FDM printing of 3D-PAD enabled the facile construction of 3D structures integrated with PAD, which would find applications in paper-based chemical and biological assays requiring organic solvents.

Дисертаційна робота присвячена розробці ресурсоощадної технології отриманню із недеревної рослинної сировини наноцелюлози та композиційних матеріалів на її основі. Доведена можливість отримання целюлози для виробництва наноцелюлози термохімічною обробкою недеревної рослинної сировини в органічних розчинниках. Розраховано константи швидкості та енергія активації процесу делігніфікації пшеничної соломи. Удосконалено процес гідролізу органосольвентної целюлози розчинами сульфатної кислоти зниженої концентрації. Розраховано математичні моделі процесу гідролізу целюлози із НДРС та ефективні значення технологічних параметрів отримання наноцелюлози. Встановлено позитивний вплив наноцелюлози як зміцнюючої добавки у композиції картонно-паперової продукції. Доцільність введення наноцелюлози в цементну композицію підтверджено актом впровадження на підприємстві цементної промисловості. The dissertation is devoted to the production from non-wood plant raw materials of nanocellulose and composite materials based on it. The processes of cooking pulp from non-wood plant raw materials in organic solvents in order to obtain cellulose suitable for chemical processing have been studied. It was found that preliminary alkaline treatment of plant raw materials with a 5% NaOH solution at a temperature of (97 ± 2) °С for 90 min leads to the removal of more than 50% of lignin and about 80% of minerals from plant materials, which contributes to subsequent efficient delignification in the process of organosolv pulping. Organosolv pulping in a mixture of peracetic acid for 180 min allows to obtain pulp with a minimum content of lignin (up to 0.61%) and minerals (up to 0.09%), which is suitable for subsequent production of nanocellulose from it. The process of hydrolysis of organosolv pulp with sulfuric acid solutions has been improved. Effective parameters of technological factors of nanocellulose production were obtained experimentally and with the use of mathematical methods. It has been proven that as a result of the hydrolysis of organosolv pulp from non-wood plant raw materials and the treatment of the suspension with ultrasound, nanoparticles with a transverse size of 10-60 nm and a crystallinity index of up to 80% were obtained. The obtained nanocellulose films are characterized by tensile strength up to 70 MPa and transparency up to 74% in the visible region of the spectrum. It were established, dependences of the quality indicators of nanocellulose (density, thickness, transparency, physical and mechanical parameters) of the main technological parameters: temperature, duration of hydrolysis and ultrasound treatment, concentration of sulfuric acid. In order to determine the quality indicators of organosolv cellulose and nanocellulose, a number of chemical and instrumental methods of analysis were performed. Analysis of the chemical composition of non-wood plant raw material showed the feasibility of using it as a source of cellulose. Images of scanning electron microscopy confirmed the size loss of stems and fibers of plant raw materials and cellulose as a result of their thermochemical treatment. The X-ray spectra of the feedstock, cellulose and nanocellulose indicate an increase in the crystallinity index of the material with each subsequent step of thermochemical treatment. Transmission electron microscopy and atomic force microscopy were performed to determine the size of obtained nanocellulose samples. Analysis of the study of nanocellulose solutions from the investigated representatives of non-wood plant raw materials, confirmed the receipt of nanoparticles of material in size 16 - 40 nm. The positive effect of nanocellulose application on the physical and mechanical properties of paper and cardboard was established. The use of nanocellulose on the surface of paper and cardboard has shown that the application of 5 g/m2 of nanocellulose, the resistance of corrugated paper to flat compression increases by 34% that is 15% more than the standard requirements. It was found that the use of 0.1% nanocellulose by weight of cement paste reduces the amount of water required for its mixing by 17% accelerates the curing process and increases the adhesion strength of cement samples by 37%, which allows the use of nanocellulose in cement slurries and repair mixtures. The feasibility of introducing nanocellulose into the cement composition is confirmed by the act of implementation at the cement industry enterprise.

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

Hybrid nanomaterials fabricated by the heterogeneous integration of 1D (carbon nanotubes) and 2D (graphene oxide) nanomaterials showed synergy in electrical and mechanical properties. Here, we reported the infiltration of carboxylic functionalized single-walled carbon nanotubes (C-SWNT) into free-standing graphene oxide (GO) paper for better electrical and mechanical properties than native GO. The stacking arrangement of GO sheets and its alteration in the presence of C-SWNT were comprehensively explored through scanning electron microscopy, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction. The C-SWNTs bridges between different GO sheets produce a pathway for the flow of electrical charges and provide a tougher hybrid system. The nanoscopic surface potential map reveals a higher work function of the individual functionalised SWNTs than surrounded GO sheets showing efficient charge exchange. We observed the enhanced conductivity up to 50 times and capacitance up to 3.5 times of the hybrid structure than the GO-paper. The laminate of polystyrene composites provided higher elastic modulus and mechanical strength when hybrid paper is used, thus paving the way for the exploitation of hybrid filler formulation in designing polymer composites.

BACKGROUND: Sneezes produce many pathogen-containing micro-droplets with high velocities of 4.5-50.0 m/s. Face masks are believed to protect people from infection by blocking those droplets. However, current filtration efficiency tests can't evaluate masks under sneeze-like pressure. The goal of this study was to establish a method to evaluate the filtration efficiency of mask materials under extreme conditions. MATERIALS AND METHODS: Efficiency of surgical masks, gauze masks, gauze, cotton, silk, linen and tissue paper on blocking micro-droplet sized starch particles (average 8.2 µm) and latex microspheres (0.75 µm) with a velocity of 44.4 m/s created by centrifugation was qualitatively analyzed by using imaging-based analysis. RESULTS: The 4 layers of silk could block 93.8% of microspheres and 88.9% of starch particles, followed by the gauze mask (78.5% of microspheres and 90.4% of starch particles) and the 2 layers of cotton (74.6% of microspheres and 87.5-89.0% of particles). Other materials also blocked 53.2-66.5% of microspheres and 76.4%-87.9% of particles except the 8 layers of gauze which only blocked 36.7% of particles. The filtration efficiency was improved by the increased layers of materials. CONCLUSION: Centrifugation-based filtration efficiency test not only compensates shortcomings of current tests for masks, but also offers a simple way to explore new mask materials during pandemics. Common mask materials can potentially provide protection against respiratory droplet transmission.

This study investigates the penetration forces during tufting of stacked dry carbon non-crimp fabrics (NCF). The stacked material with a thickness between 20 to 60 mm is made of several quadriaxial [0°/+45°/90°/-45°] NCF layers that are tufted at frequencies up to 2.3 Hz. Furthermore, the effects of the preforming process, the frequency of tufting and the thickness of specimen on the needle penetration force are investigated. Lastly, digital image correlation (DIC) is applied to study the displacement of the fabric during the unthreaded tufting of material. Future work will involve the integration of the experimental results into the simulation of the tufting process.

In this review, we summarize the recent progress in thermal conductivity analysis of nanocellulose materials called cellulose nanopapers, and compare them with polymeric materials, including neat polymers, composites, and traditional paper. It is important to individually measure the in-plane and through-plane heat-conducting properties of two-dimensional planar materials, so steady-state and non-equilibrium methods, in particular the laser spot periodic heating radiation thermometry method, are reviewed. The structural dependency of cellulose nanopaper on thermal conduction is described in terms of the crystallite size effect, fibre orientation, and interfacial thermal resistance between fibres and small pores. The novel applications of cellulose as thermally conductive transparent materials and thermal-guiding materials are also discussed.

This work investigates the spreading dynamics of three candidate sol-gel solutions, of ranging viscosities, surface tensions and densities, and compares them with water and two commercial blood substitute products. Droplets were created with different sizes (10 to75μL) and impact velocities (1.4 to 6.0m/s) to strike 176gsm cardstock. Over 2200 droplets were created using the six different fluids and their final dried stain diameter was measured. Droplet spread was plotted using the Scheller and Bousfield correlation and uses effective viscosity as a parameter for non-Newtonian fluids. Comparing the results to an expected whole human blood range validated the spread of the candidate FBS sol-gel material in passive drip bloodstain pattern simulation. These findings complement the practical application of the material as a safe substitute for demonstrating droplet spread under controlled conditions on hard paper surfaces.

Dynamic resistance can be observed in a superconducting tape carrying a DC current which is exposed to an oscillating magnetic field. This effect is attributed to the interaction between the transport current and moving fluxons, and can occur in various superconducting components including high temperature superconducting (HTS) flux pumps, fast-ramping magnets and HTS rotating machines. Although conventionally expressed in terms of a DC ‘resistance,’ the phenomenon is inherently transient in nature, and the voltage drop across the superconductor follows a time-dependent periodic waveform. Here we present experimental measurements of the dynamic resistance of different REBCO tapes carrying a DC current and exposed to an oscillating perpendicular field. Measurements of both the transient voltage waveforms and the time-averaged DC resistances are compared with numerical finite element simulations obtained using the H-formulation. We observe clear variations between the voltage response from different tapes, which can be understood in terms of their differing J c(B, θ) dependence. In particular, a key feature of the experimentally measured waveforms is the emergence of a split ‘double peak’ at higher applied fields. Graphical visualisations of the finite element data show that this coincides with a periodic increase in J c(B, θ) throughout the tape. This occurs during each cycle at those times when the applied field falls below the shielding threshold of the tape (as the penetrating field within the tape then approaches zero). Our findings show that models which assume a constant J c irrespective of local field strength cannot capture the full range of behaviour observed by experiment. This emphasises the importance of employing experimentally measured J c(B, θ) data when simulating transient effects in HTS materials.

The use of fibre-reinforced plastics or FRPs in various industries, such as aviation, automobiles, renewable energy, etc. has drastically increased over the past decades, owing to the significant strength to weight ratios they offer. The design phase of such components must also factor in thermal loads. Thermal expansions and contractions, when restricted, lead to the buildup of stresses in a material. The distribution of these stresses across the layers of a composite tube has been dealt with here with the help of an analytical study, taking into account any radially varying user-defined temperature profile. On account of geometry, the cases handled are axisymmetric and therefore, shear stresses aren’t considered.

With the aim of exploring an alternative method of nano-doping in cellulose paper and improving flashover strength of oil-impregnated paper, radio frequency (RF) magnetron sputtering method is introduced into the structural modification of insulating paper for converter transformers. In this experiment, insulating paper was treated with ZnO sputtering for 0, 7.5, 15 and 30 min, respectively. The surface morphology of dry paper was observed with a scanning electron microscope. The bonding mode of sputtered ZnO particles with cellulose matrix was investigated via attenuated total reflection infrared (ATR-IR) spectroscopy and mechanical property of the sputtered samples were studied. Surface and volume conductivities of the oil-impregnated sputtered paper were measured. Moreover, the charge dissipation characteristics of sputtered insulating paper was investigated by means of surface potential decay. In addition, trap distribution and carrier mobility of specimen were further obtained. Finally, the DC flashover strength were tested. The results showed that ZnO magnetron sputtering had a distinct influence on the structure of the insulating paper, resulting in the formation of hydrogen bond and chemical bond and an increase of the surface and volume conductivities. ZnO sputtering was found to decrease the initial potential and accelerate charge decay. Moreover, appropriate sputtering enhanced the surface flashover strength.

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.

International audience; The Covid-19 coronavirus, SARS-CoV-2, is inactivated much faster on paper (3 h) than on plastic (7 d). By classifying materials according to virus stability on their surface, the following list is obtained (from long to short stability): polypropylene (mask), plastic, glass, stainless steel, pig skin, cardboard, banknote, cotton, wood, paper, tissue, copper. These observations and other studies suggest that SARS-CoV-2 may be inactivated by dryness on water absorbent porous materials but sheltered by long-persisting micro-droplets of water on waterproof surfaces. If such physical phenomenons were confirmed by direct evidence, the persistence of the virus on any surface could be predicted, and new porous objects could be designed to eliminate the virus faster.

Nanofluids, formed by adding nanoscale particles to insulating oil, are stable and homogeneous suspensions that present advanced performance of electrical insulation and heat dissipation. This study shows a comprehensive literature review based on the related results of nano-modified insulating oils (both mineral and vegetable insulating oils) to analyse the preparation methods, stability, dielectric spectroscopy, thermal conductivity, breakdown characteristics under AC and DC voltage, the thermal aging performance of nanofluids and oil-paper interaction. Then theoretical models have been introduced to explain the electrical mechanism of nanofluids. In addition, future research is proposed for nanofluids which would be low cost, highly stable and practically applicable to the power transformers.

The effect of plant-fiber paper or silver nanowires-loaded paper interleaves on the electrical conductivity and interlaminar fracture toughness of composites was studied. Highly conductive paper was prepared by surface-loaded silver nanowires. The percolation threshold appeared at about 0.4 g/m2. The surface resistivity reached 2.3 &Omega, /sq when the areal density of silver nanowires was 0.95 g/m2. After interleaving the conductive papers in the composite interlayers, in-plane electrical conductivity perpendicular to the fiber direction was increased by 171 times and conductivity through thickness direction was increased by 2.81 times. However, Mode I and Mode II interlaminar fracture toughness decreased by 67.3% and 66.9%, respectively. Microscopic analysis showed that the improvement of conductivity was attributable to the formation of an electrical conducting network of silver nanowires which played a role in electrical connection of carbon fiber plies and the interleaving layers. However, the density of the highly packed flat plant fibers impeded the infiltration of resin. The parallel distribution of flat fibers to the carbon plies, and poor resin-fiber interface made the interlaminar fracture occur mainly at the interface of plant fibers and resin inside the interleaves, resulting in a decline of the interlaminar fracture toughness. The surface-loading of silver nanowires further impeded the infiltration of resin in the densely packed plant fibers, resulting in further decline of the fracture toughness.

The development of all-bio-based composites is one of the relevant aspects of pursuing a carbon-neutral economy. This study aims to explore the possibility to reinforce polylactic acid by the combination of cellulose and chitin nanofibers instead of a single reinforcement phase. Polylactic acid colloidal suspension, cellulose and chitin nanofiber suspensions were mixed using only water as mixing medium and subsequently dewatered to form paper-like sheets. Sheets were hot pressed to melt the polylactic acid and form nanocomposites. The combination of cellulose and chitin nanofiber composites delivered higher tensile properties than its counterparts reinforced with cellulose or chitin nanofibers alone. Cellulose and chitin appear to complement each other from the aspect of the formation of a rigid cellulose nanofiber percolated network, and chitin acting as a compatibilizer between hydrophobic polylactic acid and hydrophilic cellulose.

The effect of silica loading on the static frictional coefficient of nitrile rubber when paired with different types of papers is investigated. The influence of silica loading on the mechanical properties of nitrile rubber and its changes due to natural ageing is also examined. The objective of the study is to generate data for assessing the suitability of NBR as a lining material for impactive grippers. It is observed that the properties of NBR including frictional coefficient can be modified by varying the amount of silica. The static co-efficient of friction with most of the papers is highest at around 55 phr of silica. The properties like hardness, tear strength and resistance to oil increase with the amount of silica content while swelling index decrease with silica loading and the abrasion index peaks around 55 phr. The change in the mechanical properties due to natural ageing varies, though marginally.

Defense Threat Reduction Agency; # HDTRA1-14-C-0037, DTRA, Defense Threat Reduction Agency, M. T. Fernández-Abedul thanks the Spanish Ministry of Economy and Competitiveness (project MICINN CTQ2011-25814) for funding her stay at Harvard University. A. Ainla thanks the Swedish Research Council (VR) for a postdoctoral fellowship. A. C. Glavan acknowledges funding by the Bill & Melinda Gates Foundation, award # 51308 and DTRA award # HDTRA1-14-C-0037. M. M. Hamedi acknowledges support from Marie Curie IOF FP7 for project nanoPAD (Grant Agreement Number 330017).

Graphene has shown great potential for use in biosensors because of its versatile surface modification, good water dispersibility, and extraordinary electrical conductivity. Here, a novel enzyme-free and all-graphene electrochemical immunosensor, based on two novel graphene nanocomposites, for the ultrasensitive immunosensing of α-fetoprotein (AFP) was reported. Noncovalent ultrathin gold nanowire functionalized graphene sheets (GNWs/GO) with the extraordinary biological and electrical properties, which exhibited high water solubility and further biological molecule functionalization, was prepared in situ solution phase to be used as an enhanced electrochemical sensing platform. In addition, a new electrocatalyst, CuS nanoparticle-decorated graphene (CuS/GO) composites was successfully prepared by a simple method for in situ growth of CuS on the surface of graphene sheets. Covalent binding of the detection antibody of AFP on the CuS/GO composites produced a sensitive electrochemical bioprobe for detection of AFP by sandwich immunosensing. The corresponding immunosensor, employing an inexpensive and portable 3D paper-based analytical device, possessed a wide calibration range of 0.001–10 ng mL−1 and a low detection limit of 0.5 pg mL−1 (S/N=3), which was successfully applied to the detection of AFP in serum samples from both healthy people and cancer patients. The present work thus demonstrated the promising application of graphene-based nanocomposites in developing highly sensitive, environmentally friendly, and cost-effective electrochemical biosensors.

The aim of this study was to improve the electrical resistivity, mechanical properties, and interfacial properties between the carbon fiber (CF) and cellulose of conductive paper containing 10% CF so as to better meet the demands for electric heating wood floors. With waterborne polyurethane (WPU) treatment and nitrogen plasma modification methods, the interfacial properties between CF and cellulose were improved dramatically. Fourier transform infrared spectrometry (FTIR) revealed that the plasma modification method reduced the C-H contents and introduced numerous polar groups onto the CF surface. Scanning electron microscopy (SEM) showed that the CF modified by WPU and plasma had good adhesion with cellulose. The tensile index, tensile energy absorption index, and burst index of the paper were enhanced because of the plasma and WPU coating. The carbon fiber and WPU method presented good synergistic action with respect to mechanical properties and electrical resistivity, and the lowest electrical resistivity of conductive paper was reduced from 0.68 •cm2 to 0.44 •cm2.

The in-plane shear strengths (IPSS) of copy paper, filter paper, and sack paper were obtained from an asymmetric four-point bending (AFPB) test. Rectangular tabs of medium-density fibreboard (MDF) were bonded to the paper specimen. The length of the clearance between the tabs was varied, and the influence of the clearance on the IPSS value was investigated. The IPSS obtained from the AFPB test was compared with that obtained from a 35° off-axis tension (OAT) test, which was proposed in a previous study. The IPSS values obtained from the AFPB tests on the copy paper and sack paper were significantly lower than those obtained from the 35° OAT tests because of the localised buckling caused by the negative principal stress. In contrast, the IPSS values obtained from the AFPB and OAT tests on the filter paper were in agreement when the clearance length was >5 mm because the buckling effect was excluded.

Background:Paper is one of the important inputs for the printing industry, and the most important leading parameter in the printing process is its brightness. Brightness can be brought to paper using coatings and sizing. Desired surface properties and, most importantly, surface roughness can be achieved by changing the contents of the coating and sizing of the materials it contains. The use of biomaterials is becoming more important in the paper industry, as they represent substances with a lower carbon footprint. Fish scales are already used as a filling material, cosmetic material and fish food, as well as for determining the age of fish.Methods:Fish scales were brought to different sizes by a milling process. Paper formulations including different amounts of fish scales were prepared with fish scales, and coatings on raw paper were subjected to test printings in IGT-C1, with formulations and physical characteristics of coatings such as brightness, lightfastness, strength, adhesion etc. being determined.Results:Regarding the value of yellowness, mixtures of 2.5%-10% can be used. The maximum value of brightness was obtained from a mixture of 10%. Aging visibly changed the colors.Conclusions:The coatings obtained were brighter than the initial coating compositions. The top quality formulation was the coating with 5% medium-sized fish scale particles.

The majority of disposable cups are made from paper plastic laminates (PPL) which consist of high quality cellulose fibre with a thin internal polyethylene coating. There are limited recycling options for PPLs and this has contributed to disposable cups becoming a high profile, problematic waste. In this work disposable cups have been shredded to form PPL flakes and these have been used to reinforce polypropylene to form novel paper plastic composites (PPCs). The PPL flakes and polypropylene were mixed, extruded, pelletised and injection moulded at low temperatures to prevent degradation of the cellulose fibres. The level of PPL flake addition and the use of a maleated polyolefin coupling agent to enhance interfacial adhesion have been investigated. Samples have been characterised using tensile testing, dynamic mechanical analysis (DMA) and thermogravimetric analysis. Use of a coupling agent allows composites containing 40 wt.% of PPL flakes to increase tensile strength of PP by 50% to 30 MPa. The Young modulus also increases from 1 to 2.5 GPa and the work to fracture increases by a factor of 5. The work demonstrates that PPL disposable cups have potential to be beneficially reused as reinforcement in novel polypropylene composites.

We investigated the filling process of cellulose-based paper with natural clay nanotubes and their mixtures with hydroxypropyl cellulose (HPC) that is commonly used as glue and consolidant for degraded paper. A comprehensive characterization of the materials was carried out through morphology, wettability, thermal degradation, and tensile properties. The treatment with halloysite nanotubes generated a decrease of the paper mechanical performance and did not alter the thermal properties. The co-presence of HPC and nanoparticles generated a more uniform nanotubes distribution in the paper fibrous structure and a significant enhancement of both the mechanical properties and the surface hydrophobicity with respect to the HPC treatment. This work proposes the use of halloysite/HPC mixture in a new protocol for paper consolidation and represents a starting point to develop, with a biocompatible approach, smart composite material in which the nanotube cavity is filled with active species for paper protection or active response to external stimuli. © 2014 Akadémiai Kiadó, Budapest, Hungary.

The widespread use of melt processed, single grain (RE)–Ba–Cu–O bulk superconductors [(RE)BCO], where RE = Y, Gd or Sm, is limited predominantly by the poor mechanical properties of these inherently brittle, ceramic-like materials. The high density of flaws, such as cracks and voids, within the single grain microstructure leads directly to a low fracture toughness. As a result, the Lorentz forces, generated when these materials carry current in the presence of a large magnetic field, create stresses sufficiently large to cause brittle failure. The addition of Ba–Cu–O (liquid phase) and Ag to the precursor composition prior to melt-growth has been demonstrated to be effective in improving the mechanical properties of these technologically important materials. In this work, we characterise the mechanical failure of single grain YBCO bulk superconductors in terms of a Weibull statistical distribution. In addition, differences in fracture mechanisms have been studied to provide a better understanding of how the provision of additional liquid phase and silver produces YBCO single grains with better resulting mechanical properties and how these can be improved further.

This paper is devoted to study a structure of SiC-based materials using ultrasonic tomography method. The SiC-based materials were fabricated from preceramic paper using spark plasma sintering (SPS) method. Also as part of the study the Young's modulus and density of sintered materials were determined and the effect of sintering pressure changing to this parameters value was investigated. The preceramic paper is a composite material including a matrix of organic cellulose fibers and inorganic powder filler (SiC). The sintering temperature and pressure were 2373 K and 20-40 MPa, respectively. The holding time for the sintering process was 10 min. The density of sintered materials was investigated by the hydrostatic weighing method. Ultrasonic tomography was implemented using of single-channel sensor at 10 MHz frequency. © Published under licence by IOP Publishing Ltd. Russian Science Foundation, RSF: 19-19-00192 The research was supported by the Russian Science Foundation (grant No. 19-19-00192) as well as by

Our preliminary study investigates an automated, vibrating fiber optic tip for dusting of kidney stones during thulium fiber laser (TFL) lithotripsy. A (0.75-mm diameter and 5-mm length) magnetic bead was attached to the fiber jacket, centered 2 cm from distal fiber tip. A solenoid was placed parallel to the fiber with a 0.5-mm gap between solenoid and magnetic bead on fiber. The solenoid was used to create a magnetic force on the bead, inducing fiber vibration. Calibration tests for fiber motion in both air and water were performed. The ablation crater characteristics (surface area, volume, depth, and major/minor axis) of uric acid stones were measured using optical coherence tomography, after delivery of 1500 TFL pulses at 1908 nm, 33 mJ, 500 μs, and up to 300 Hz, through 50-, 100-, and 150-μm-core fibers. The resonant frequency was dependent on fiber diameter and rigidity, with a cutoff pivot point for optimum vibration amplitude at 4 cm. Maximum fiber displacement is about 1 mm in water and 4 mm in air. For 50-, 100-, and 150-μm-core fibers, ablated surface area averaged 1.7, 1.7, and 2.8 times greater with vibrating fiber than fixed fiber, respectively. For these fibers, ablation volume averaged 1.1, 1.5, and 1.1 times greater with vibrating fiber than fixed fiber, given a fixed energy per pulse, respectively. Our preliminary study demonstrates the functionality of an automated, vibrating fiber system for stone “dusting,” with significantly larger surface area but similar ablation volumes as a fixed fiber. Future studies will focus on optimization of fiber parameters (especially displacement) and miniaturization of system components to facilitate integration into ureteroscopes.

Metamaterials are engineered materials that gain their properties from the repeating patterns of their structures. Here we discuss paper-based metamaterials, with the honeycomb structure, and a possible auxetic design of them.Read Complete Article at ijSciences: V3201410597 AND DOI: http://dx.doi.org/10.18483/ijSci.597

Precipitated calcium carbonate (PCC) is a filler that is widely used for papermaking, and lime sludge is a special type of PCC recovered from the black liquor from kraft pulping. There has been some concern that lime sludge may interfere with the development of paper’s hydrophobicity in comparison with commercial PCC and ground calcium carbonate (GCC) due to the presence of impurities when alkyl ketene dimer (AKD) is used as the sizing additive. In this work, fillers with different particle size distributions were prepared, and the effects of particle composition on surface chemistry of fillers, adsorption for AKD, sizing degree of final paper sheets, and retention behavior of fillers were evaluated. The results showed that, through matching different particle size distributions for lime sludge fillers, the negative zeta potential decreased from -26.2 mV to -20.8 mV, the specific surface area decreased from 15.0 m2/g to 9.1 m2/g, and total pore volume decreased from 0.037 cm3/g to 0.026 cm3/g, which was favorable for the low adsorption for AKD. Consequently the sizing effect of filled paper was improved. Moreover, the retention rate also was increased by changing the particle size distribution of lime sludge.

The goal of this study was to analyze the effects of cellulose fibers loading by precipitation in-situ of calcium carbonate over the properties of printing paper obtained from mixtures of the softwood and hardwood fibers. The effects of fibers with in-situ loading were analyzed comparatively with conventional paper loading respectively, by adding precipitated calcium carbonate into fiber stock. The effectiveness of the methods was evaluated by various analyses and investigations: calcium carbonate content, Scanning electron microscope (SEM) images, X-ray diffraction, optical and mechanical properties of the paper sheets. The evaluation of the effects on paper properties led to the conclusion that, at the same filler content, the in-situ loading method gives higher opacity and brightness than conventional methods. The utilization of cellulose fibers with in-situ loading as additive, shown as a modification of the ratio between fibers with in-situ loading and fibers without loading, regardless of whether they are softwood or hardwood fibers, allowed us to optimize printing paper properties, especially regarding the relationship between optical and strength properties.

The migration behaviour of four photo-initiators (BP, EHA, MBP and Irgacure 907) was studied by ‘printing’ onto four different food-packaging materials (Kraft paper, white cardboard, Polyethylene (PE)-coated paper and composite paper) and tracking movement into the food simulant: Tenax-TA (porous polymer 2,6-diphenyl furan resin). The results indicated that the migration of the photo-initiators was related to the molecular weight and log Ko/w of each photo-initiator. At different temperatures, the migration rates of the photo-initiators were different in papers with different thicknesses. The amount of each photo-initiator found in the food was closely related to the food matrix. The Weibull model was used to predict the migration load into the food simulants by calculating the parameters τ and β and determining the relationship of the two parameters with temperature and paper thickness. The established Weibull model was then used to predict the migration of each photo-initiator with respect to different foods. A two-parameter Weibull model fitted the actual situation, with some deviation from the actual migration amount.

Bacterial cellulose is an ideal material that is sustainable, biodegradable and inherently capable of functionalization. Hence this has been functionalized with a single component, Ni to exhibit multiple functionalities such as electrical conductivity, magnetic sensitivity as well as catalytic activity in both dried and hydrogel forms. A novel, simple ‘inverse chemical reduction’ technique has been developed to incorporate this component and make bacterial cellulose multifunctional. This technique mercerizes and opens the interfibrillar spaces which results in the formation of nanoparticles that lead to percolating paths for conduction. The flexible sheet becomes electrically conducting with just 20 vol% of nanoparticles in the composite as determined by thermogravimetry. The room temperature electrical conductance increases by about 7 orders of magnitude, 10−6–10 S on changing the Ni-precursor solution concentration from 0.015 to 0.02 M, indicating this to be the critical concentration for conduction percolation. The composites are highly magnetic at room temperature with a maximum energy product of 140 J m−3, comparable to some of the commercially available bonded oxide magnets. The hydrogel form of the nanocomposite is found to be catalytically active. The catalytic activity is retained even after leaving the nanocomposite hydrogel in water for 12 h in water.

The response of paper to humidity variations is a complex, inherently multi-scale problem. The hygroscopic swelling of individual fibres and their interactions within the fibrous network govern the macroscopic, sheet-level response. At this scale, moisture induced instabilities and out-of-plane deformations may occur, which are critical for a number of industrial applications. This work specifically focuses on several aspects of this important issue. A macroscopic phenomenological hygro-mechanical model is first proposed, which aims at predicting moisture induced out-of-plane deformations in paper sheets. The constitutive model is based on the relation between these deformations and typical irreversible phenomena associated to the history of paper manufacturing, i.e. the release of dried-in strains. The model is used to describe bending induced by moisture gradients through the thickness of the sheet as well as buckling due to moisture variation in the presence of mechanical constraints. The results of the model show that the anisotropic sheet-level hygro-expansion has a strong influence on the instability phenomena. Moreover, a comparison with experiments provides adequate semi-quantitative estimates. An additional step is made towards the multi-scale understanding of paper hygro-mechanics. The fundamental physical mechanisms governing the macroscopic moisture induced response are investigated on the basis of the underlying fibrous network. To this aim, a meso-structural model is developed which consists of a network of fibres randomly positioned in a planar region according to an orientation probability density function. A series of network simulations reveals that upon moisture content variations the expansion of the inter-fibre bonding regions essentially drives the overall deformation. Particularly in the case of anisotropic fibre orientation, this explains the origin of the macro-scale anisotropic hygro-expansion, which is essential for the observed sheet-level instability phenomena.

This paper presents a multi-scale approach to predict the effective hygro-mechanical behaviour of paper sheets based on the properties of the underlying fibrous network. Despite the vast amount of literature on paper hygro-expansion, the functional dependence of the effective material properties on the micro-structural features remains yet unclear. In this work, a micro-structural model of the paper fibrous network is first developed by random deposition of the fibres within a planar region according to an orientation probability density function. Asymptotic homogenization is used to determine its effective properties numerically. Alternatively, two much more idealized micro-structural models are considered, one based on a periodic lattice structure with a regular network of perpendicular fibres and one based on the Voigt average. Despite their simplicity, they reproduce representative micro-structural features, such as the orientation anisotropy and network level hygro-elastic properties. These alternative models can be solved analytically, providing closed-form expressions that explicitly reveal the influence of the individual micro-scale parameters on the effective hygro-mechanical response. The trend predicted by the random network model is captured reasonably well by the two idealized models. The resulting hygro-mechanical properties are finally compared with experimental data reported in the literature, revealing an adequate quantitative agreement.

During the last two decades, cellulose nanofibres (CNF) have emerged as a promising, sustainable reinforcement with outstanding potential in material sciences. Though application of CNF in papermaking is recent, it is expected to find implementation in the near future to give a broader commercial market to this type of cellulose. The present review highlights recent progress in the field of the application of cellulose nanofibres as additives in papermaking. The effect of CNF addition on the wet end process is analysed according to the type of pulp used for papermaking. According to the literature consulted, improvement in paper's overall properties after CNF addition depended not only on the type and amount of CNF applied, but also in the pulp's origin and treatment. Bulk and surface application of CNF also presented significant differences regarding paper's final properties. This review also revises the mechanisms behind CNF reinforcing effect on paper and the effect of chemically modified CNF as additives AcknowledgmentsThe authors want to acknowledge the financial support givenby the Spanish Ministry of Economy and Competitiveness by thefunded project reference CTQ2013-48090-C2-2-R

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. Article in Lithuanian. Popierius ir atspaudai – kompozicinės medžiagos Santrauka.Popierius ir atspaudai analizuojami kaip kompozicinės medžiagos. Aprašomas atspaudų spausdinimas kaip kompozicinės medžiagos susidarymo procesas spausdinant, lakuojant ir laminuojant. Aptariama, kodėl ir kaip turėtų keistis atspaudo savybės, lyginant su popieriumi. Raktiniai žodžiai:kompozicinė medžiaga; popierius; popieriaus fizikinės savybės

We present a simple and cost-effective method for rendering networks of cellulose fibers, such as paper, fabrics or membranes, superparamagnetic by impregnating the individual fibers with a reactive acrylic monomer. The cellulose fibers are wetted by a cyanoacrylate monomer solution containing superparamagnetic manganese ferrite colloidal nanoparticles. Upon moisture initiated polymerization of the monomer on the fiber surfaces, a thin nanocomposite shell forms around each fiber. The nanocomposite coating renders the cellulose fibers water repellent and magnetically responsive. Magnetic and microscopy studies prove that the amount of the entrapped nanoparticles in the nanocomposite shell is fully controllable, and that the magnetic response is directly proportional to this amount. A broad range of applications can be envisioned for waterproof magnetic cellulose materials (such as magnetic paper/tissues) obtained by such a simple yet highly efficient method.

SUMMARY Objective To evaluate, through the application of different dentin bonding systems, the influence of wetness on shear bond strength in enamel. Methods This study evaluated three etch-and-rinse adhesive systems (Scotchbond MP [used with and without primer]; Singlebond; and Prime&Bond 2.1) and two self-etching adhesive systems (Clearfil SE Bond; and Xeno IV). Flat bovine enamel surfaces were either air-dried for 30 seconds or blotted with absorbent paper after acid-etching for the conventional bonding agents or before the application of self-etching bonding agents. The resin composite EsthetX was bonded to flat surfaces that had been treated with one of the adhesives, following the manufacturer's instructions. After being stored in water at 37°C for one week, bonded specimens were broken in shear. Data were evaluated with two-way analysis of variance (ANOVA) and Student-Newman-Keuls tests (α=0.05). For comparing each condition individually, regardless of the adhesive or wetness condition, a one-way ANOVA and a Student-Newman-Keuls test (α=0.05) were applied. Results The two-way ANOVA showed significant differences among adhesive systems. An interaction effect was also observed (p Conclusion The all-in-one adhesive behaved differently depending on whether the enamel surface was dry or wet.

A trihybrid clone of Paulownia fortunei x tormentosa x elongata was used for pulp and paper production using the soda-anthraquinone (AQ) process, comparing the results with those from Paulownia fortunei. An autohydrolysis process had been previously carried out on this raw material. A composite central experimental design and a multiple regression were used for modeling and optimizing the process. A valuable liquid phase could be obtained from the autohydrolysis process of Paulownia, trying to minimize cellulose degradation for pulp and paper production. A compromise to maximize the glucan and minimize the xylan contents in the postautohydrolysis solid phase could be achieved at 187.5ºC and 15 minutes. A suitable cellulosic pulp with kappa number ranging from 12.2 to 69.2 and ISO brightness from 18.2 to 30.6% presented better results than those from other studies. Regarding handsheets physical properties (tensile index 37.3 N·m/g ) and viscosity (848 cm3/g), significant improvements could be obtained when compared with previous results of a similar process using Paulownia fortunei or Paulownia elongata.