Key Engineering Materials Vol. 559

Abstract: Electrochemical properties and possibilities of manufacturing the anodes based on water-soluble binders such as carboxymethylcellulose (CMC) have been investigated in order to create prerequisites for development of “green” technologies for recyclability of LIBs components.In this work an advanced anode was designed. A kind of nanosized carbon coated Si composite was synthesized. The charge/discharge test reveals that the advanced anode shows a reversible capacity of 600 mAh/g. The improved performance was ascribed to the carbon shell of Si and CMC binder. The binder CMC buffers the expansion of the Si and the improved electric contact between the active material and copper current collector.

Abstract: Hyperbranched polyphenylenes containing triphenylamine groups were synthesized through Ni⁰-catalysed polycondensation of aromatic tribromides. The values of the photoluminescence quantum yields depend on nitrogen content in the obtained polymers. It is shown that polyphenylenes due to high levels of thermal stability and conductivity could be good template for OLEDs with light-emitting organic metal complexes in the active layer.

Abstract: Three different kinds of polyols from rapeseed oil were synthesised and characterized during this study. Afterwards, using these polyols rigid polyurethane foams were produced, which are used as thermal insulation material in construction industry and in production of refrigerators. Polyols from rapeseed oil were synthesised by epoxidation, transamidization and transesterification methods. One rapeseed oil based polyol was synthesized by partial epoxidation of the double bonds in fatty acid chains and overall opening oxirane rings by using diethylene glycol. Other two methods transamidization and transesterification of ester bonds of triglyceride were carried out using diethanolamine and triethanolamine respectively. To use these polyols for production of polyurethane foams, hydroxyl value, acid value, water content, viscosity and density of polyols were determinated. The functionality of obtained polyols was calculated on the base of number-average molecular weight and hydroxyl value. After laboratory trials a pilot scale production of the rapeseed oil polyols was carried out in 50 L reactor. From synthesized polyols rigid polyurethane foam samples were produced in laboratory scale and also in semi industrial scale, using industrial high pressure spraying equipment machine. Technological parameters, density and closed cell content were determined for obtained polyurethane foams.

Abstract: A method for determining the flexural Young’s modulus of polymeric materials from deformation diagrams of thin-walled circular cylindrical shells in compression in the region of geometrical nonlinearity has been elaborated. A numerical solution is found by the finite-element method (ANSYS.) The existence of a unified deformation diagram in generalized coordinates is established, from which the flexural Young’s modulus is determined. To validate the method, the Young’s modulus of specimens was found experimentally.

Abstract: The aim of this study is to improve the heat resistance performance of polyurethane based adhesives for the manufacture of shoes. Four polyurethane adhesive compositions most used in the domestic shoe industry have been investigated: PU-503, VU-252, KYSPO-1 and D-274. The main components of polyurethane compositions are urethane rubber, zeolite, ethyl acetate and acetone. It has been found that modification of VU-252, KYSPO-1 and D-274 with zeolite in the amount of 0.5-1% allow to increase the heat resistance to 150° C while that of PU-503 - to 200° C. Besides it has been found that adhesive compositions can be recommended for the manufacture of special fire-resistant shoes that could withstand high thermal loads.

Abstract: The paper is devoted to investigation of frequency-dependent electric properties of polymer nanocomposites. The experimentally acquired frequency characteristics of complex dielectric permittivity are substituted by equivalent mathematical models of dielectric relaxation. It is shown that such substitution is valid, provided that the selected relaxation model allows shaping the synthesized frequency curves in a sufficient range and the statistical significance of the measurement data is within a satisfactory range.

Abstract: In this work, composites of isotactic polypropylene (PP) with three unvulcanized elastomers – terpolymer of ethylene-propylene-dicyclopentadiene (EPDM), chlorinated polyethylene (CPE) and copolymer of acrylonitrile-butadiene (NBR) – have been investigated. The purpose of the investigation was to create PP/elastomer blend composites of significantly different compositions (with an excess of PP, intermediate ones, and with an excess of elastomer) and to study the dependence of tensile behaviour and elastic properties on the blends with different component ratio. Tensile properties have been recognized from the stress-strain curves. The changes of elastic modulus have been characterized with respect to the Hashin-Shtrikman upper and lower bounds and the Davies equation. Calorimetric properties of PP blends with elastomers (crystallinity and melting behaviour of polypropylene phase) have also been investigated with the method of differential scanning calorimetry (DSC).

Abstract: Recently, a deliberate interest to look for composites that are eco-friendly and biodegradable appears. Therefore materials based on raw materials derived from natural resources of plant are being studied. One of the most promising bio-based polymers that have attracted the interest of many researchers is poly(lactic acid), which is made from plants and is readily biodegradable. Cellulose is one of the strongest and stiffest fibres available and it has a high potential to act as reinforcing agent in biopolymers. In our work we esterified cellulose using stearoyl chloride in ionic liquid and studied the effect of cellulose stearate addition to matrix polymers on thermal and rheological properties.

Abstract: Cellulose stearates were prepared in a 1-butyl-3-metylimidazolium chloride ionic liquid. The addition of base pyridine as well as catalyst Tin octoate sufficiently increases the degree of hydroxyl group substitution. The new path for preparation of cellulose mixed esters, namely cellulose acetate stearate (CAS), is performed. The 1H NMR data confirmed the structure of obtained mono- and mix- cellulose esters.

Abstract: The aim of the present study was to improve the paper handsheets parameters by adding biodegradable natural polymer – chitosan. The addition of chitosan in the amount of 2-4% improved tensile strength of the handsheets by up to 20% in dry condition and by up 5 times in wet state. Addition of chitosan increases the hydrophobic properties of paper as it was revealed by contact angle and water penetration dynamic measurements.