Polymer Science, Series D最新文献

In this work, the ability of calcium, magnesium, and zinc stearates to oxidative destruction of polyethylene was studied. For comparison, the samples of pure polyethylene and polyethylene with the commercial additive D₂W were selected. Infrared spectroscopy data showed that samples with magnesium stearate accumulated double carbon bonds after 96 h of exposure in a climate chamber. In samples with zinc stearate, an asymmetric vibrations of COO groups disappear after 192 h of exposure in a climate chamber. All samples accumulated carbonyl groups resulting from polymer chain scission. After 96 h of aging, the sample with calcium stearate showed better oxidizing properties compared to other stearates. Mechanical test data also confirms the conclusion that the sample with calcium stearate is more susceptible to oxidative degradation among the studied stearates.

A significant number of different types of damage to structural materials, as well as various scenarios of their accumulation, up to destruction, require not only the use of a significant set of experimental methods and the methods of theoretical materials science and molecular physics, but also for developing appropriate mathematical models. These models perform two functions. On the one hand, they make it possible to give a reasonable interpretation of complicated processes, and, on the other hand, they can forecast the evolution of the material under specific operating conditions. Some features characterizing the description of material degradation and destruction based on kinetic approaches are considered.

Today, an important feature of scientific research consists in environmentally safe and biodegradable polymeric materials. Polylactide (PLA) and compositions based on this polymeric compound are being active investigated in world science. One of the main issues that should be considered before using PLA consists in understanding the mechanisms of its biodegradation including mixtures based on this polymer. This work is aimed at studying the mixtures based on PLA with polycaprolactone (PCL) and natural rubber (NR) in the course of biodegradation. After incubation in soil, pure polycaprolactone demonstrates clearly visible structural defects and mycelium on the surface. It has been established that both polycaprolactone and natural rubber undergo biodegradation more rapidly than polylactide. Obtaining PLA/PCL and PLA/NR compositions makes it possible to enhance the effect of biodegradation. As a result of the study, a change in the thermophysical characteristics of the mixtures has been revealed, which indicates the onset of the destruction process.

This article is a continuation of a series of articles on welding parts made of polymer composite materials based on thermoplastics. The fourth article in the series discusses the most common methods of quality control and testing of welded joints of products made of polymer composite materials based on thermoplastic binders. Typical defects in plastic welded joints have been identified. Technologies for destructive and nondestructive testing of welded joints of plastic products are considered.

In this paper, the problem of modifying the physicochemical and rheological characteristics of bitumen binders with polyethylene wax additives is considered. Based on the study of physicochemical and rheological properties, it is shown that the addition of these modifiers results in binders with improved characteristics, such as the softening temperature, rutting resistance, and fatigue cracking. Taking into account the quantitative estimate for the degree of change in the properties of modified bitumen binders, optimal doses of modifiers are determined.

The influence of the concentration of various ethylene–vinyl alcohol (EVAlC) and ethylene–vinyl acetate copolymers on the properties of high-density and low-density polyethylenes is studied to develop compositions for utilization and recycling of polymer multilayer films containing EVAlCs as a barrier layer. It was found that EVAlCs have a lesser negative effect on the properties of mixtures based on high-density polyethylene.

This paper is devoted to estimating the effect of coloring (RAL 7037) polycarbonate and polysulfone with different yellowness indices on a complex of optical, physicomechanical, and rheological properties. It is shown that the introduction of color additives into heat-resistant polymers does not radically change their principal rheological and physicomechanical properties and does not require any modification for the methods and conditions of their processing.

Porphyrin–polymer systems are promising materials for their use in biotechnology, biochemistry, and medicine. The creation of composite materials from porphyrins expands the possibilities of using both high molecular weight compounds and porphyrins. Polylactide–porphyrin film samples obtained by solution watering method are studied in this work. It was found that the density of the film compositions decreases with an increase in an amount of porphyrin in the polymer matrix. A Soret peak of porphyrin immobilized into the polylactide matrix splits (425 and 447 nm) and shifts bathochromically. The addition of 5,10,15,20-tetrakis(4-n-hexyloxyphenyl)porphyrin changes the elastic behavior and strength properties. Shear modulus, elastic modulus, and tensile strength decrease with an increase in an amount of porphyrin in the polylactide matrix. Relative elongation at break increases slightly, and the Poisson’s ratio is almost unchanged compared to those of starting polylactide.

An analysis of methods for separating metal powders of different sizes for gas-thermal coating technologies was carried out. The results of research on the development of a new method for separating different fractions of powders of a given granulometric composition and an installation for their preparation are presented. An algorithm for operating an experimental installation for separating powder materials into fractions is analyzed in detail. The features of reducing the degree of fluctuation increases and the process of fluidization of material particles in the process of their separation are described. Data were obtained to determine and evaluate the relaxation of the gas flow in the proposed installation.

The physicomechanical properties of KGE-3/16 sealant glue and their stability under the influence of thermal cycles and climatic factors simulating long-term storage have been studied. It has been revealed that this sealant glue is resistant to the influence of destabilizing climatic factors, characterized by a high stability of its properties with a unique combination of high strength and elasticity, and can find application in radio electronic equipment.