EFFECT OF AGING ON FILM PROPERTIESOF ETHYLENE–ALPHA OLEFIN COPOLYMERS

摘要

Film toughness of certain ethylene – alpha olefin copolymers of high impact strength, shows significant agingeffects, decreasing with time. In this work we studied the time and temperature dependence of film aging of severalcopolymers of varying molecular structure. Film aging appears to be associated with the presence of highlybranched polymer chains (>30 branches per 1000 carbon atoms). It is speculated that the thermally activatedrearrangement of such branched species, over time and under film storage conditions, leads to film aging. Higherfilm storage temperatures lead to faster aging. It is possible to employ an “accelerated aging” testing protocol, so asto obtain longer-term aged data from a short-term test, which would be useful in an industrial production setting.