Influence of the Processing Method on the Heat Resistance of a Recycled Block Copolymer of Propylene and Ethylene Filled with Rice Hulls

Polymer composites based on recycled thermoplastic polymers filled with biodegradable components of plant origin are developed. Repeated thermal and mechanical action on polymers during their processing in the presence of dispersed phase particles leads to a change in the thermophysical and strength characteristics of finished products. The patterns of change in the heat resistance of the polymer composites based on a recycled block copolymer of propylene and ethylene and rice hulls processed by injection molding and pressing are studied. It is shown that filling the recycled polymer with rice hulls leads to an increase in the heat resistance of the composites, which is characterized by an increase in the deflection temperature under load, the Vicat softening temperature, and the decomposition temperature during thermogravimetric analysis in an inert atmosphere. Compared to the injection molding method, pressing of the polymer composites makes it possible to obtain more heat-resistant plastic products. This is obviously due to the differing degrees of crystallinity of the polymer phase. The high cooling rate of the polymer composite melt during the filling of the injection mold does not provide the time necessary for the corresponding change in the conformation of macromolecules and the formation of the crystalline phase. As a consequence, an increase in the content of the amorphous phase of the recycled block copolymer of propylene and ethylene reduces the heat resistance of the prototypes.