Controlled degradation by melt processing with oxygen or peroxide of ethylene/propylene copolymers

Abstract

Ethylene/propylene copolymers with the same composition but different sequence of monomer distribution were submitted to thermal degradation in an inert atmosphere, in the presence of oxygen and/or free radical initiators. The analysis of the reaction products, consisting of lower molecular weight macromolecules with double bonds and oxygenated functional groups, was performed by viscosimetric, FTIR, NMR, and differential scanning calorimetry (DSC) analysis. The presence of linear ethylene blocks of different length with distinct melting temperatures was detected by the self-annealing methods based on DSC. The results are used to evaluate the effect of the copolymer macromolecules' microstructure and the processing conditions on the degradation extent and the molecular structure of the degradation products.

3,3,6,6,9,9-Hexaethyl-1,2,4,5,7,8-hexaoxacyclononane at 296 K

“…Cyclic peroxide derivatives have been studied mainly for two reasons. Firstly, they are potentially useful radical initiators, for example, in the bulk polymerization of styrene (Cerna et al, 2002) or for controlled-rheology polypropylene (Pucci et al, 2004). In this application, their performance is similar to that presented by a multifunctional initiator, giving rise to high molecular weight polystyrene at a high reaction rate.…”