Experimental study of gas diffusion layers nonlinear orthotropic behavior

One of the most important components of PEMFC is the gas diffusion layer (GDL), owing to its key role in the reactant diffusion, water management, thermal and electron conductivity. Therefore, the GDL must have an optimal stiffness to ensure these transport functions during numerous hydrothermal cycles. The understanding of its behavior is still a remaining issue. Its orthotropic mechanical behavior requires a series of mechanical characterizations in the plane of the fibers and out of plane. In addition, there are different manufacturing processes for GDL in sheet or roll form to optimize its functional properties. A macro porous layer (MPL) or different PTFE contents might be added by different manufacturers to optimize its performance. In this study, we have performed several mechanical tests differentiating between in plane and out of plane properties in order to characterize different GDLs available on the market. All of the experimental work has been done in the machine (MD) and cross machine direction (CD) according to the fiber orientation. The different GDL types were then classified into categories presenting similar mechanical response.

Effect of antiblock and slip additives on the properties of tubular quenched polypropylene film

In the present investigation, silica and talc were used as antiblock additives with slip additive to investigate their effects on tubular quenched polypropylene (TQPP) film properties. Polypropylene (PP) powder was compounded with additives in twin-screw extruder and subsequently processed through TQPP machine to prepare the films. Tear and tensile properties [in machine direction (MD) and transverse direction (TD)] and surface properties of the produced TQPP films were investigated in terms of optics and coefficient of friction (CoF). The effect of conditioning time on CoF was also studied. Addition of slip agent alone to PP did not show any significant change in tear strength, CoF and tensile properties, whereas CoF reduced drastically by adding both slip and antiblock agents in combination. Reduction in CoF values were found to be more pronounced in the presence of silica-based antiblock compared to talc-based antiblock. Film surface morphology was further examined by field-emission scanning electron microscopy. The tear strength and the gloss of TQPP film decreased slightly in presence of only antiblock agents, but the tensile strength was found to increase. It was also found that tensile properties of TQPP films were superior in silica-based formulation, whereas tear strength was better in talc-based formulation in MD and TD.

Art Paper for Large Wood Relief Block Printing – A Paper Development Study

Wood relief block printing was developed in China in the seventh century and is used today for many art printing applications. The presented research project describes the development of an art paper product applicable for large wood relief block printing from laboratory scale to large semi commercial production of art paper for printing image sizes of up to 44-inch (1118 mm) by 96-inch (2400 mm) at outdoor steam roller printing events or smaller indoor printing press applications. The improvement of the paper properties from laboratory development, small laboratory paper machine and semi commercial paper machine run for the production of the final art paper showed an improvement throughout the process development for the optical and mechanical paper properties and exceeded the set values set by the artist using the art paper. The produced art paper with a basis weight of 260 g/m² and a thickness of 171 µm is produced from a mixture of 70% northern bleached hardwood Kraft pulp and 30% northern bleached softwood Kraft pulp. The ISO brightness of the art paper off-white (egg-shell) colour was at 63.2% and the ISO color value for L, a, b. at 90.8, 1.1, and 12.6 respectively. The art papers surface roughness and porosity as a parameter for ink attachment and penetration is for the top side 2179 ml/min and for the bottom side (wire side) 2326 ml/min, whereas porosity was measured at 1668 ml/min. Bending stiffness in machine direction and cross machine direction was measured at 157mN and 70 mN respectively. Burst strength was measured at 2.24 kPA·m²/g.

Investigation of the Mechanical Behavior of Electrodes after Calendering and Its Influence on Singulation and Cell Performance

Battery cell production is a complex process chain with interlinked manufacturing processes. Calendering in particular has an enormous influence on the subsequent manufacturing steps and final cell performance. However, the effects on the mechanical properties of the electrode, in particular, have been insufficiently investigated. For this reason, the impact of different densification rates during calendering on the electrochemical cell performance of NMC811 (LiNi0.8Mn0.1Co0.1O2) half-cells are investigated to identify the relevant calendering parameters. Based on this investigation, an experimental design has been derived. Electrode elongations after calendering in and orthogonal to the running direction of the NMC811 cathode are investigated in comparison with a hard carbon anode after calendering. Elongations orthogonal to the machine direction are observed to have no major dependencies on the compaction rate during calendering. In the machine direction, however, significant elongation occurs as a dependency of the compaction rate for both the hard carbon anode and the NMC811. In addition, the geometric shape of the NMC811 electrodes after separation into individual sheets is investigated with regard to different compaction rates during calendering. It is shown that the corrugations that occur during calendering are propagated into the single electrode, depending on the compaction rate.

Regulating the Deformation Properties of Paper by Varying the Degree of Its Anisotropy

Mechanical properties are crucial in assessing the paper quality. Deformation and strength properties of paper are determined by the strength and stiffness of the interfiber and intermolecular hydrogen bonds. The contribution ratio of interfiber and intermolecular hydrogen bonds to the strength of paper can be changed by adjusting the degree of its anisotropy. The article presents the results on a study of the deformation properties of laboratory anisotropic paper samples from kraft bleached softwood pulp with a beating degree of 30 °SR. The samples had basic weight of 90 g/m2 and the degree of stiffness anisotropy TSIMD/CD of 1.75–4.08. They were made by using Techpap SAS automatic dynamic handsheet former (Grenoble, France), with varying forming parameters – diameter of the nozzle, motion speed of the forming wire, and injecting speed of pulp. Deformation properties were determined by tensile test and processing of the stress-strain dependence (σ−ε). The outcomes have shown that, an increase of the fiber orientation degree in paper structure by changing the forming parameters caused a change in the nature of the paper deformation under tension. Increasing the fiber orientation degree in the structure of paper made it possible to increase the strength by 55 %, tensile stiffness by 63 % in the machine direction, while reducing the extensibility by 10 %. In the cross direction, it was possible to decrease tensile stiffness by 33 %, strength by 55 %, and increase the extensibility by 5 %. Anisotropy of tensile strength was 1.73–6.00. The greatest effect was obtained for the elasticity modulus in the pre-failure zone E2 (2.8–38.6). It means that, fiber orientation had a key importance when large deformations in the samples took place. The established quantitative regularities allowed optimizing the values of the deformation and strength properties of paper, and their ratio in the machine direction and cross direction due to the variation of the forming parameters. For citation: Rech D., Potasheva A.N., Kazakov Ya.V. Regulating the Deformation Properties of Paper by Varying the Degree of Its Anisotropy. Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 5, pp. 174–184. DOI: 10.37482/0536-1036-2021-5-174-184

PREPARATION OF BACTERICADAL FILLERS FROM GEORGIAN HEULANDITE-CLINOPTILOLITE AND THEIR APPLICATION FOR PAPER PRODUCTION. II. BACTERICADAL PAPER

The purpose of present work was to obtain bactericidal materials using heulandite-clinoptilolite from the Rkoni plot of the Tedzami deposit, Eastern Georgia, and to use them as a filler for the production of bactericidal paper. Materials remaining the zeolite crystal structure, containing over 130 mg/g of silver, 70 mg/g of copper, and 55 mg/g of zinc, and showing bacteriostatic activity towards pathogenic bacteria and fungi were prepared in laboratory and the filled papers were manufactured on the production lines of the GPM company. It was found that the introduction of zeolite fillers leads to an increase in the grammage, thickness and density of the paper, as well as to a certain decrease in the tensile strength in the machine direction. The introduction of zeolite fillers containing divalent metals causes a significant change in surface properties, and samples with a certain copper content become absolutely waterproof. Testing of bacteriostatic activity by disc diffusion method revealed only activity of paper with a silver-containing filler against E. coli and staphylococcus, while the colony forming unit assay indicates the activity of all metal-containing samples against staphylococcus and all zinc-containing samples against E. coli. The greatest activity against E. coli is shown by paper with a high content of zinc, against staphylococcus, paper with a high content of copper. These results are very important from a practical point of view, since they open up the possibility of replacing silver with copper and zinc.

Three-dimensional visualization and characterization of paper machine felts and their relationship to their properties and dewatering performance

Polymeric felts are commonly used in the papermaking process on the paper machine wet end, in the press section, and in the dryer section. They provide an important function during paper manufacturing, including as a carrier or support; as a filter media assisting with water removal on the paper machine; in retention of fibers, fines, and fillers; and in some applications, such as tissue and towel, to impart key structural features to the web. These felts can have highly interwoven complex internal structures comprised of machine direction and cross-machine direction yarns of varying sizes and chemical compositions. Here, we present a non-intrusive three-dimensional (3D) image visualization method using advanced X-ray computed tomography (XRCT). This method was used to characterize the complex 3D felt structure and determine the water removal characteristics of some commonly used paper machine felts. The structural features analyzed include porosity; specific pore-yarn interfacial surface area; 3D pore size distribution; 3D fiber or yarn-size distribution; and their variations through the thickness direction. The top, middle, and bottom layers of the felt have very different structures to assist with water removal and impart paper properties. The size distribution of the yarns, as well as the pores in the different layers of the felt, are also inherently different. These structural features were non-intrusively quantified. In addition, variation in the structural characteristics through the thickness of the felts and its potential role in papermaking is explored. In addition to the 3D structural characteristics, permeability characteristics and water removal characteristics, including rewetting of select felt samples, have also been experimentally determined. It is interesting to observe the relationship between key structural features and permeability and water removal characteristics. These relationships can provide additional insights into press felt design, as well as ways to improve product properties and the dewatering efficiency and productivity of the paper machine.

Chitosan/Montmorillonite Coatings for the Fabrication of Food-Safe Greaseproof Paper

Here, we report a non-toxic method for improving the oil-resistant performance of chitosan coated paper by coating the mixture of chitosan and montmorillonite (MMT) instead of coating chitosan solution only. Through combining MMT into the chitosan coatings, the coated paper exhibited a lower air permeability and enhanced oil resistance under a lower coating load. For coated papers C2.5 and C3 by coating 2.5% (w/v) and 3% (w/v) chitosan without adding MMT in the chitosan coating, the coating load was 3.76 g/m2 and 3.99 g/m2, respectively, and the kit rating values were only 7–8/12. Regarding the sample C2M0.1 coated by the mixed solution containing 2% (w/v) chitosan and 0.1% (w/v) MMT, its coating load was only 3.65 g/m2, the paper permeability after coating was reduced to 0.00507 μm/Pa·s, owing to the filling of MMT into the cellulosic fibers network, and the kit rating reached 9/12. Moreover, C2M0.1 showed improved mechanical properties, whereby its tearing resistance was 5.2% and 6.6% higher than that of the uncoated paper in the machine direction and the cross direction, respectively.

Study on technology of greaseproof paper for dry food packaging

This paper presents the research results that established the main technological conditions in the production of greaseproof paper, used as the packaging of dry food as the proportion of pulp types, the degree of the beating of pulp, the use of chemicals and oil and greaseproof resistant agent to the properties of the paper on a laboratory scale. At the same time, experimental production and technology conditions were regulated on a 3 ton/day capacity line. The paper quality produced is equivalent to the imported paper products of the same type which is consumed in the market: basis weight: 42.5 g/m2; tensile breaking length: MD (Machine Direction): 7,520 m, CD (Cross Direction): 3,740 m; tear index: MD: 6.8 mN.m2/g, CD: 5.4 mN.m2/g; burst index: 5.6 kPa.m2/g; Cobb60: 17.2 g/m2; KIT rating: 8; ensuring food safety and hygiene.

Development of compressive testing device for glass fiber based single face corrugated structure sheet, and estimation of buckling strength of straight panel of that structure sheet

<abstract> <p>This work aims to reveal the in-plane-compressive characteristics of Glass Fibre based single face corrugated Structure Sheet (GFSS) by developing a loading holder of the both ends of the panel of GFSS in the direction of the cross machine direction. A grooved end-support device was developed and exmined. In order to set stably and quickly a straight panel of GFSS on the compressive-testing apparatus, the width and the depth of the holder's groove were varied against the geometrical size of the panel, and the stability and reproducibility of compressive deformation of the panel was experimentally investigated. When changing the height of the panel and reinforcing the both ends of the panel by dipping instant adhesives, the deformation behavior and the buckling strength was characterized in three modes: a short height crushing without lateral deflection, a small lateral deflection mode as the intermediate state, and a triangle-like folding as a long height crushing.</p> </abstract>