Polymer Science, Series D最新文献

This work, based on stepwise dilatometry data, presents the results of a study of the influence of fibrous basalt content on the crystallization processes of composites based on isotactic polypropylene. The influence of filler content and the regularity of changes in specific volume and free specific volume depending on temperature are considered. The filler concentration in the polypropylene composition varied from 1.0 to 30.0 wt %. The mechanism and type of crystal growth in the polymer matrix in the presence of fibrous basalt have been established.

The results of a study of the resistance of a polymer composition based on epoxy resin with a biocidal effect to the exposure of the marine environment of the tropical climate have been presented. The biocidal effect was achieved by using dispersed copper(I) oxide particles, both encapsulated with polylactide and unencapsulated particles. It has been shown that the highest efficiency of the biocidal effect, along with the best strength indicators of such a composition, is observed at a mass fraction of encapsulated particles of ~0.7–0.8%. The tensile strength of the corresponding composition increases by 30% compared to the unfilled polymer. This is due to the formation of additional cross-links in the polymer network as a result of the interaction of the encapsulated particles with the polymer. A twofold decrease in strength characteristics has been noted after climatic tests. This is due to severe damage to the surface of the samples under study. The paper shows that the proposed approach to creating a biocidal composition using encapsulated particles is more effective when using such materials in the air, rather than in the sea environment of a tropical climate.

The work is devoted to the investigation of the possibility of application of modified secondary polystyrene with properties improved due to the introduction of nanoclay into its composition in some branches of technology. It is shown that joint introduction of thermoplastic elastomers and nanoclay into secondary polystyrene fundamentally changes the main rheological and physical and mechanical properties of the compositions but requires no substantial change in the methods and modes of their processing.

The changes in morphology and structure of polylactide/natural rubber nonwoven fibrous materials after exposure to soil microbiota are studied. Fibrous composite material samples were obtained by electrospinning from solution. The amount of natural rubber was 5–15 wt %. X-ray amorphous structure was revealed by X-ray diffraction in the initial samples and after their degradation in the soil. The morphology of the fibrous materials changed after exposure to soil microbiota: dark spots and defective areas appeared. Thermogravimetric analysis showed that the onset degradation temperatures of all samples and the temperatures of peak maxima shifted to lower temperatures. The changes in chemical structure of the nonwoven fibrous materials were found by IR spectroscopy. Bands appeared at 3500–3000 and 1660–1550 cm^–1, which confirms that the degradation process proceeds in polymeric materials.

The wide range of binders and fillers used in textolite production makes it possible, by means of various combinations of these main components, to obtain a variety of materials with valuable technical characteristics. The study examines the technological features of textolite production on the basis of phenol-formaldehyde resins and the influence of the binder content in the fabric filler on the product properties. For filler impregnation, we employed a method based on application of phenol-formaldehyde resin predissolved in ethyl alcohol to the required concentration.

Halogen-containing unsaturated polyarene ether ketones were obtained by nucleophilic substitution reaction in a high-boiling solvent, N,N-dimethylacetamide. The structure and main properties of the synthesized polyarene ether ketones were studied. The composition and structure of the polymeric materials were confirmed by IR spectroscopy, X-ray diffraction analysis, and differential scanning calorimetry. It has been shown that polyarylene ether ketones are well soluble in aliphatic and amide solvents, possess high heat and fire resistance, and can find application as heat-resistant structural polymeric materials.

Some aspects of the problem of adhesive fracture of aircraft panels made of composite materials under fatigue loading are considered. Algorithms of computer modeling of the delamination development process are described. Various methods of nondestructive testing for identifying the size and location of adhesive failure are analyzed. The cause of adhesion failure between anisotropic layers even under uniaxial tension is explained. The growth of delamination area under cyclic tension is described by an equation in the form of a power-law dependence on the range of the elastic energy release rate. For aircraft panels made of laminated carbon-fiber-reinforced plastics, the independence of the delamination growth rate from its current area is experimentally confirmed.

The influence of application and washing modes under conditions of modification of hydroxyl-containing cellulose materials by products of hydrolytic condensation of triethoxy(octyl)silane on the hydrophobicity of the surface has been studied. It has been shown that an increase in the concentration of hydroxyl groups on the surface promotes immobilization of the organosilicon modifier. Regularities of wetting of modified cellulose materials by liquids of various natures have been established (found).

The process and operational characteristics of a casting formulation of polypropylene are studied by introducing fibrous and nanoscale fillers into its composition. A correlation between the physical and mechanical and color characteristics of the composites upon joint introduction of inorganic and nanofibers is found.

This article presents a literature data review on the nonisocyanate method for producing epoxyurethane adhesives. The article considers the results of studies of epoxyamine compositions modified with cyclocarbonates, in which the kinetics of reactions between cycloclocarbonates and amines to form hydroxyurethanes, as well as aminolysis processes during joint curing of cyclocarbonates (CCs) and epoxy oligomers, were studied. It is established that the functionality and structure of CCs influence on the adhesive, technological, and operational characteristics of modified epoxyamine compositions. It is shown how the interaction of cyclocarbonates with excess amines can produce prepolymers with different structure and molecular weight with NH₂-end groups, and, when curing them with bisphenol diglycidyl ether, it is possible to create hybrid hydroxyurethane/epoxides with a controlled structure (architecture). Using Laprolat 803 oligoether tricyclocarbonate, adhesive compositions have been developed with high adhesive and cohesive characteristics that are water- and vibration-resistant with increased viability, including those suitable for gluing wet surfaces.