title: Effect of microstructure on the thermo-oxidation of solid isotactic polypropylene-based polyolefins.
abstract: In the present work we aim to clarify the role of the microstructure and the crystalline distribution from the thermo-oxidation of solid isotactic PP (iPP) and ethylene-propylene (EP) copolymers. The effects of the content and quality of the isotacticity interruptions, together with the associated average isotactic length, on the induction time (ti) as well as on the activation energy (Eact) of the thermo-oxidation are analysed. Both parameters have been found to change markedly at an average isotactic length (n1) of 30 propylene units. While tireaches a minimum whenn1is approximately 30 units, Eactincreases quasi-exponentially as the number of units decreases from 30. This variation can be explained in terms of changes induced in the crystalline interphase, i.e. local molecular dynamics, which are closely linked to the initiation of the thermo-oxidation of isotactic PP-based polyolefins.
authors.affiliation: Instituto de Ciencia y Tecnología de Polímeros, CSIC, Juan de la Cierva, 3, 28006-Madrid, Spain.
authors.forename: Mario
authors.initials: M
authors.lastname: Hoyos
authors.affiliation: Instituto de Ciencia y Tecnología de Polímeros, CSIC, Juan de la Cierva, 3, 28006-Madrid, Spain.
authors.forename: Pilar
authors.initials: P
authors.lastname: Tiemblo
authors.affiliation: Instituto de Ciencia y Tecnología de Polímeros, CSIC, Juan de la Cierva, 3, 28006-Madrid, Spain.
authors.forename: José Manuel
authors.initials: JM
authors.lastname: Gómez-Elvira
keywords: ethylene-propylene copolymers; microstructure; polypropylene; thermo-oxidation