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Preparation and Invesrigation of Mechanical Properties of Composites Based on Secondary Polypropylene and Modified Basalt Fibers

The use of secondary materials resulting from recycling is currently receiving increased attention, since their use reduces the anthropogenic burden on the environment. In this regard, composite materials based on recycled polypropylene (PP) and short-chopped basalt fibers (BF) are prepared. To improve the adhesion of BF to the polymer matrix, their surface was treated with CCl4 vapors in a flow reactor in order to replace the oxygen atoms with chlorine atoms. Then, the chlorinated surface was treated in a CH4 stream to replace chlorine with hydrocarbon groups. Composites contained from 5 to 20% BF; each composite was heated at temperatures of 500, 650 and 750°C. Stress-strain curves at tension and compression were obtained for all samples. The modulus of elasticity at tension increased to 2120 MPa with a BF content of 20%, and for the initial secondary PP this modulus is equal to 705 MPa. The strength increased to 42 MPa (for the initial secondary PP, the strength is equal to 32.0 MPa). The specific impact strength increased to 18.3 kJ/m2 (for the initial secondary PP this value is 14.4 kJ/m2). The chemical structure of hydrocarbon groups most compatible with PP was determined by calculation using the Cascade computer program (INEOS RAS). IR studies and microanalysis showed the presence of such groups on the surface of the BF, which are chemically bound to silicon atoms.