Hindered amine stabilisers as long-term heat stabilisers for polypropylene

A comparison is made between the efficiency of hindered amine stabilisers ( HAS) and phenolic antioxidants as stabilisers against the thermo-oxidative degradation of polypropylene (PP) and their ability to reduce the oxidation rates of decalin, squalane and decalin/lauraldehyde mixtures. The stabilis ation mechanism of phenolic antioxidants differs from that of HAS. Phenolic AOs are able to stop the oxidation of model compounds and PP. They are eff ective until they are consumed. The effectiveness of HAS depends on the sys tem into which they are incorporated. When aldehydes can be formed (squalan e and PP) or are added (decalin/lauraldehyde mixture) HAS are more effectiv e than in cases where aldehydes do not play a role (decalin). The results w ith squalane and decalin/lauraldehyde mixtures are comparable to those with PP. The best comparison is found for squalane. (C) 1999 Elsevier Science L td. All rights reserved.