TECHNOLOGICAL FEATURES OF INJECTION MOULDING OF DYNAMICALLY VULCANIZED NANOCOMPOSITES BASED ON RANDOM POLYPROPYLENE, NITRIL BUTADIENE RUBBER AND BENTONITE.

The work deals with the influence of the technological parameters of injection molding on the basic physicomechanical characteristics of nanocomposites of dynamically vulcanized thermoplastic elastomers based on random polypropylene and nitrile butadiene rubber of various grades. The equipment used was a single-screw molding unit with 4 temperature zones of the material cylinder. Rotational and translational movement of the screw allowed for uniform dispersion of the mixed components of the mixture. To improve the compatibility of the polymer components, a graft copolymer of polypropylene with maleic anhydride at the value of 1-3 wt. % was used as compatibilizer. The influence of the temperature regime of the material cylinder of the injection machine and the molding pressure on the ultimate tensile stress, elongation at break, elastic modulus on bending and volume shrinkage is studied. It is shown that an increase in the indicated technological parameters of molding leads to an increase in strength indicators and a noticeable decrease in the volume shrinkage of dynamically vulcanized thermoplastic elastomer nanocomposites. The influence of mold temperature and holding time under pressure on the ultimate tensile stress and elongation at break of nanocomposites has been considered and optimal conditions for their cooling in the mold established. Besides, the effect of nanocomposites of dynamically vulcanized thermoplastic elastomers with various types of nitrile butadiene rubber on the ultimate tensile stress and elongation at break of nanocomposites analyzed. It revealed that, unlike random polypropylene, dynamically vulcanized nanocomposites are characterized by isotropic properties which make it possible to obtain high-quality structural materials of complex configuration. [ABSTRACT FROM AUTHOR]