features of isothermal crystallization of composites based on high-density polyethylene and fibrous basalt

The paper presents the results of studying the effect of fibrous basalt content on the crystallization regularities of high-density polyethylene-based composites. The crystallization process was studied using stepwise dilatometry in the temperature range of 20 – 210 °C. The fibrous basalt content in HDPE varied within 1 – 20 wt. %. The dilatometric research method made it possible to determine the dependence of the specific volume of composites on temperature. The results of the analysis allowed us to determine the first-order phase transition, the second-order phase transition (glass transition temperature), the free and occupied specific volume of the composites. The studies showed that fibrous basalt is distributed in the free volume of the polymer matrix, which is mainly located in the interspherolitic amorphous space. The study of kinetic regularities of composite crystallization in Kolmogorov – Avrami coordinates made it possible to establish that the growth mechanism of crystalline formations during continuous formation of nucleation centers largely depends on the fibrous filler content. In particular, it was established that the initial wet-density polyethylene and composites with 1 – 5 wt. % filler content are characterized by a three-dimensional spherulitic type of growth of crystalline formations. Composites with 10 – 15 wt. % fibrous filler content form a lamellar type of crystal growth. Samples with 20 wt. % filler content are characterized by the simplest rod-shaped type of growth of crystalline formations.