Key Engineering Materials Vol. 899

Abstract: The synthesis of polyphenylene sulfide in the presence of catalytic systems based on montmorillonite and various lithium salts has been studied, and conditions have been identified that accelerate the process and obtain a polymer with a given microstructure. The rheological, thermal, and physicomechanical.

Abstract: The effect of heat treatment on the structural changes and properties of the synthesized PPS samples was studied. The optimum temperature and the exposure time of the heat treatment of PPS were established, which allow to increase thermal stability, improve rheological and mechanical characteristics.

Abstract: During the study, solutions and film materials have been obtained with a concentration of polyvinyl alcohol in distilled water in the range of 1 ... 15 %. The rheological properties of the resulting solutions have been studied by rotational viscometer HAAKE VT 550 at a temperature of 20° C and 80° C. Film materials have been molded by cast film method. The elastic and strength properties of the film materials samples have been determined with a Gotech 7000M universal testing machine. It has been shown that with an increase in polyvinyl alcohol concentration, there has been a decrease in the elastic and strength properties. Samples of film material with 1% and 5% polyvinyl alcohol content completely dissolve in water in 10 and 20 minutes, respectively.

Abstract: The study of the properties of PEEK blends with different melt flow rate (MFR) and carbon-filled composites based on them was carried out. It was found that with an increase in the relative difference in the MFR of the blended PEEKs, there is an increase in the deviation of the experimental MFR values from the additive ones. Up to a relative difference in the MFR of the components equal to 60%, the blends obey the additivity rule. It is shown that the achievement of a certain MFR value by blending polymers with different viscosities leads to the production of materials with similar properties. Carbon-filled composites based on PEEK blends also demonstrate very similar rheological, mechanical and thermal properties, which indicates the effectiveness of the method of blending PEEKs with different viscosities to achieve the required rheological properties.

Abstract: This article studies the recycling of medical masks by the extrusion method. The main mechanical and physicochemical properties of recycled medical masks have been researched. It was revealed that the processed medical masks contain high physical and mechanical properties. The article shows the introduction of recycled masks leading to an increase in the manufacturability of the homo-and a block copolymer of polypropylene. In the case of a block copolymer, an increase in elastic-strength properties is observed. The introduction of recycled masks does not significantly affect the thermophysical properties of the homo-and a block copolymer of polypropylene.

Abstract: The article presents a scientific review on the development of composite materials based on polyphenylene sulfide and glass fillers. The main ways (finishing of the filler surface, synthesis of a polymer matrix with functional groups, treatment of the filler and polymer matrix surface with a plasma flow) of increasing interfacial adhesion at the glass fiber-polyphenylene sulfide interface are considered.

Abstract: The design and dimensional characteristics of the spinneret affect not only the geometry of the hollow fiber, but also the transport properties of the hollow fiber membranes. In the literature available today, there is a limited number of works in which the influence of the design and dimensional characteristics of the spinneret is studied. In this work, using the example of polysulfone hollow fiber membranes, it was shown that the use of a spinneret with smaller annular diameters leads to an increase in the gas permeability of the hollow fiber membrane with a decrease in the value of the ideal selectivity for the He/CO₂ gas pair. It was found that using the spinneret with large annular diameters, the hollow fiber membrane is obtained with a smaller value of the average pore size of the flow, which is in agreement with the obtained data on gas permeability.

Abstract: An important practical and fundamental problem in the production of porous polymer membranes is the study of the porous structure and the detection of "defects" or large pores in the area of ​​the membrane. Known porosimetry methods cannot solve this problem. This work proposes a new non-destructive express method for studying the porous structure of asymmetric polymer membranes in high-intensity electric fields. This method can be successfully implemented on both flat sheet and hollow fiber membranes with a known porous structure. On the example of hollow fiber membranes made of polyacrylonitrile and polysulfone an assessment of the chemical structure effect of the membrane material on the high-voltage discharge currents in a highly inhomogeneous electric field through hollow fiber membranes with a given pore size was made. Under normal conditions and an average intensity of an inhomogeneous electric field E = 5 kV/cm, the results obtained allow us to conclude about a certain practical potential of the developed express method.

Abstract: The features of the dependence of the dielectric constant and the specific volume resistance of the composite "80 wt. % SKI-3 + 20 % wt. % LDPE" from the content of nanosized filler particles - aluminum and black carbon. The use of modern methods for studying macroscopic properties and electron microscopy made it possible to study the structure and morphology of the supramolecular formations of the composite. Models and possible physical mechanisms leading to extreme changes in εʹ and ρ_V at low concentrations of nanoparticles are presented.

Abstract: The paper presents a comparative analysis of the dynamic loading of a polymethyl methacrylate (PMMA) target by a polyethylene (PE) projectile exposed to laser radiation with similar initial energy characteristics of the projectile and the laser pulse. The similarities and differences in the mechanisms of the target's response and its destruction to high-speed mechanical and laser action are shown. A higher efficiency of laser irradiation in the destruction of PMMA was found, and the conditions for the transition of the fracture mechanism from brittle to elastic-plastic were shown.