Influence of polypropylene processing conditions on its thermal, physical and mechanical characteristics

Abstract

The effect of the method and the number of processing cycles on polypropylene thermal and physical-mechanical properties is studied. It is shown that, regardless of the processing method, the thermal stability of polypropylene, expressed by the temperature of the onset of decomposition, decreases, the content of thermally stable compounds increases, and the degree of crystallinity of the polymer decreases by 5.6–6.5%. With an increase in the number of heating-cooling cycles simulating the multiplicity of thermoplastic polypropylene processing, the temperature of the onset of decomposition decreases from 211°C to 166°C, the mass of the sample decreases due to its partial decomposition, the melting point decreases from 166°C to 158°C, the degree of crystallinity of the polymer decreases. With an increase in the number of polypropylene processing cycles by compounding in the mixing chamber of the plastograph, an increase in the load on the rotation of the screws during plasticization and in the melt flow is observed, while the strength and elongation at break of the plastic sample consistently decrease..