Abstract
Studies were carried out to establish the mechanisms of structure formation during crystallization of polymer composites based on polyethylene, polypropylene or polycarbonate filled with copper microparticles. The researches were executed using a technique, the first stage of which consisted in the experimental determination of crystallization exotherms of composites, and the second – in the theoretical analysis based on the obtained exotherms of the structure formation characteristics. A complex of studies on determination of crystallization exotherms for investigated microcomposites was carried out. The regularities of the cooling rate influence of composites, the method of their production and the mass fraction of filler on the temperature level of the beginning and ending of crystallization, the maximum value of the reduced heat flux, etc. were established. It is shown that for the applied methods of obtaining composites the increase of their cooling rate causes the decrease of the indicated temperatures and heat flux. It is established that the value of the mass fraction of the filler has a less significant effect on the characteristics of the crystallization process.The regularities of structure formation of polymer composites at the initial stage of crystallization with the involvement of data on crystallization exotherms and nucleation equations are investigated. The presence of planar and three-dimensional mechanisms of structure formation at this stage has been established. It is shown that the ratio of these mechanisms is influenced by the type of polymer matrix and the method of obtaining composites.For the second stage of crystallization, which occurs in the entire volume of the composite, the results of experiments on crystallization exotherms were analyzed on the basis of the Kolmogorov-Avrami equation. It is shown that the structure formation of polyethylene-based composites occurs by the three-dimensional mechanism, and on the basis of polypropylene and polycarbonate – by the mechanism of the stressed matrix
Highlights
Polymeric micro- and nanocomposites occupy an important place among synthetic materials, which successfully replace traditional natural materials
The aim of research is to establish the regularities of the formation of the structure of polymer microcomposites based on polyethylene, polypropylene and polycarbonate when they are filled with copper particles with varying in a wide range of the main defining parameters
Characteristics of the crystallization process of polymer microcomposites based on polyethylene, polypropylene and polycarbonate filled with copper particles, with different methods of obtaining them for Vt=5.0 K/min on the mixing of the components in dry form and in the polymer melt, respectively, were subjected to this study
Summary
Polymeric micro- and nanocomposites occupy an important place among synthetic materials, which successfully replace traditional natural materials. This is largely due to the complex of unique physical and technological properties of such composites. The development of polymer composite materials with the necessary complex of properties involves conducting systematic researches on the choice of polymer matrix and type of filler, analysis of the patterns of structure formation of composites and more. Promising uses of polymer microcomposites are associated with the application of their highly heat conductive modifications. The latter can be used to replace metal elements in electric motors and generators for the manufacture of heat exchange surfaces for various purposes and so on. The high efficiency of using these composite materials to create heat exchangers is associated with such characteristics as the required thermophysical and anti-corrosion properties, relatively low specific gravity, and so on
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