Natural weathering of some new ethylene copolymers

The outdoor ageing of three ethylene-octene copolymer films having differen t values concerning crystallinity and thermal characteristics has been stud ied. The thermal oxidation strength of these: films diminishes to only 3 mi n after 500 exposure hours. After 1000 exposure hours the concentration of the carbonyl groups increases and the mechanical properties undergo a meani ngful diminution. The materials under study have a behaviour very close to that of an isotactic polypropylene film previously examined under similar c onditions. Unlike polypropylene and polyethylene these copolimers give rise to a lot of peroxide derivatives after about 3000 exposure h. (C) 1999 Els evier Science Ltd. All rights reserved.