Environmental degradation of a novel ethylene–propylene copolymer in thick sheets R. Gallo a , L. Brambilla b , C. Castiglioni b , S. Ipsale c , F. Severini b, * , F. Quasso d , G. Consolati d a Dipartimento di Chimica Industriale e Ingegneria dei Materiali, Universita ` di Messina, Salita Sperone, 98166 S. Agata di Messina, Italy b Dipartimento di Chimica, Materiali e Ingegneria Chimica ‘‘G. Natta’’, Politecnico di Milano, Piazza Leonardo da Vinci, 32, 20133 Milan, Italy c Assessorato Ambiente, Provincia Regionale di Messina, Via S. Cecilia is. 105, 98100 Messina, Italy d Dipartimento di Fisica and INFM, Politecnico di Milano, Piazza Leonardo da Vinci, 32, 20133 Milan, Italy Received 16 March 2004; received in revised form 17 September 2004; accepted 26 September 2004 Available online 21 November 2004 Abstract The outdoor ageing of a commercial ethylene–propylene copolymer (Adflex) is investigated. Different techniques (infrared spectroscopy, thermal analysis, scanning electron microscopy, mechanical tests and positron annihilation life- time spectroscopy) are used in order to obtain a comprehensive view of the modifications occurring during the environ- mental ageing of thick sheets of this copolymer. The degradation of the material is ascribed to a morphology variation, arising from the separation of amorphous oxidised copolymers initially dispersed in the bulk of the material. Weath- ering process takes places with increase of the bulk density of the sample. Ó 2004 Elsevier Ltd. All rights reserved. Keywords: Infrared spectroscopy; Thermal analysis; Ethylene–propylene copolymer; Environmental degradation; Positron annihilation 1. Introduction Polyethylene (PE) and polypropylene (PP) are among the most employed plastic materials and the production of their copolymers and blends with controlled proper- ties may significantly extend their applications. Due to the fact that PE and PP are practically immiscible, phys- ical and mechanical properties of their blends can be im- proved with the addition of compatibilisers, which modify the morphology and interfacial adhesion of the multiphase blends. Ethylene–propylene copolymers are often employed as compatibilisers [1] in PE–PP blends. A new class of heterogeneous materials consisting of a mixture of ethylene–propylene copolymers of different C 2 /C 3 ratio, which show interesting performances both as raw materials themselves and in blends with PP and PE, is commercially available from ‘‘Montell’’, now ‘‘Basell’’ Ferrara, Italy, under the trade name Adflex. Semi-crystalline and amorphous copolymers are fi- nely dispersed since the blend is obtained directly during 0014-3057/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.eurpolymj.2004.09.014 * Corresponding author. Tel.: +39 022 399 3227; fax: +39 027 063 8173. E-mail address: febo.severini@polimi.it (F. Severini). European Polymer Journal 41 (2005) 359–366 www.elsevier.com/locate/europolj EUROPEAN POLYMER JOURNAL