The ageing of modified glass-reinforced polypropylene in air and in antifreeze

The comparative behaviour of modified and unmodified glass-reinforced polyp ropylene during ageing in air (135 degrees C) and in antifreeze (115 degree s C) with exposure up to 80 days was investigated. Approaches to thermostab ilization of the composites are proposed. Mechanical properties (tensile st rength, flexural strength, impact strength) and melt flow have been measure d for original and aged samples. According to Hg-porosimetry data, the unmo dified composite has a loose macroporous structure. Ageing leads to progres sive phase separation. In contrast, the original modified composite is char acterised by a dense structure; ageing leads to the structure compacting, a nd pore size decreases. The unmodified composite displays a drastic failure of mechanical properties after 10 days of heating. Modified thermostabiliz ed glass-filled polypropylene reatins its thermooxidative stability during ageing in air as well as in antifreeze, its molecular weight characteristic s remain practically constant. (C) 2000 Elsevier Science Ltd. All rights re served.