Certain Aspects of the Optimization of Processing of Polymer Composites

Abstract

Design of polymer composites [1] is based on polymer processing theory [2-6] and involves solving polymer technology problems [7]. Most of the polymer processing technologies are based on heat-and mass-transfer phenomena, and further elaboration of design of polymer composites requires enhancement of existing technologies and development of new ones. The development of new technologies can be aimed at reducing energy consumption on intense thermomechanical treatment of materials being processed. These tendencies are consistent with the increasing production of composites. Along with the chemical composition and molecular weight distribution of such disperse systems, of decisive importance are their structure and rheological behavior, the surface properties, the diffusion and mass transfer through the interface, and the particle size distribution. The properties of such multicomponent distributed heterogeneous systems, including their phase stability, are largely determined by the efficiency of mixing of components and the sizes of distributed particles. The character of mixing and dispersing may be different.The flow equations in mathematical models of multiphase media [8][9][10] and their dynamics in the course of processing in various equipment contain a term involving the shear stress and strain, which allows one to evaluate the processes under investigation from a single standpoint. In viscous media, the dispersing and mixing on rollers, in extruders, etc., are determined by the shear stress and strain [3,4]. In low-viscosity disperse systems, it is difficult to create high shear stresses that would ensure particle breakdown. For comparison, we can present data on the shear stress in high-and lowviscosity disperse media. Globules of the fluorine rubber SKF-26 are broken down in mill mastication at a shear stress of approximately 5 MPa. The shear stress at the interface in the formation of an emulsion in the presence of surfactants is 10 -3 MPa [11]. In liquidphase chemical engineering processes, the mass transfer may be accompanied by interface instability phenomena induced by hydrodynamic and hydrochemical interactions [12]. Nonetheless, analysis of generalized parameters of activating mixing of multiphase media containing a liquid phase in a rotary pulsed apparatus also took into account the shear stress and strain [13].The purpose of this work was to consider specific features of the dynamic behavior of certain disperse systems and to find ways of optimizing the production and processing of polymer composites in low-viscosity media. The objects of investigation were the latex DL-940, based on a butadiene-styrene copolymer with a styrene content of about 65%; the acryl latexes AK-252A and AK-252B and their mixtures; films obtained from the latexes and their mixtures; latex-zeolite composites with a zeolite content of 30 wt %; aqueous solutions of polyacrylic acid, gelatin, or starch with carbon (30% carbon); and nonwoven materials impregnated with a binder produced from the latexes subjected to vibration wa...

Регулювання Прохідного Перерізу Формуючої Головки Екструдера З Використанням Механотронної Системи

“…У хімічній технології при переробці полімерів у вироби методом екструзії, зміни форми поперечного перерізу та площі каналів формуючих головок, змінюють у процесі течії фізико-механічні параметри матеріалу (щільності, в'язкості), неізотермічність потоку. [2].…”

Mathematical model of the flow of polymer melt in the extruder forming die

“…One of the main directions of development of mechanical engineering for the production of the finished products from polymer melts is an increase of spinning rate and combination of technological operations, decrease of energy and metal intensity of the equipment, mechanization and automation of processes using microprocessor technology. When solving all the above problems the development of mathematical models, methods of computation and optimization of molding process by extrusion with subsequent verification and implementation of the obtained results into production is becoming particularly urgent [1,2].…”