Siberian Federal University

The article presents the results of studies of the influence of aluminum hydroxide concentration on the regularities of changes in the crystallization process of composite materials based on a polypropylene random copolymer / processing aid / aluminum hydroxide (PP-R/ LIBAID T-2 /Al(OH)3). In this study, LIBAID T-2 was used as a physical coupling agent to improve the compatibility between polypropylene random copolymer and aluminum hydroxide. The amounts of aluminum hydroxide varied within the range of 1–50 wt%. The crystallization process of composites was studied by the stepwise dilatometric method under a load of 5.3 kg on the IIRT-1 device, converted into a dilatometer. The following parameters have been determined, such as specific volume, density, occupied and free specific volume, temperature of first-order phase transition and isothermal crystallization, and glass transition temperature. The glass transition temperature of the studied polymer composites increased with an increase in the content of aluminum hydroxide in the polymer matrix. The crystallization temperature for all studied samples was 120 °C. With an increase in the amount of aluminum hydroxide, a decrease in the specific volume value and, accordingly, an increase in density were observed. Based on the Kolmogorov- Avrami equation, the kinetic regularities of isothermal crystallization of the studied composites were studied and the mechanism of formation of crystalline structures depending on the content of the introduced filler in the composition of the polypropylene random copolymer was described