Model linear ethylene-butene copolymers irradiated with gamma-rays

Two model linear polyethylenes of different molecular weights and very narr ow molecular weight distributions were subject to gamma-ray irradiation und er vacuum. Irradiations were conducted at two temperatures: 25 and 135 degr ees C. Number average and weight average molecular weight of irradiated sam ples was measured by LALLS and membrane osmometry, and the distribution of molecular weights was studied by GPC. The presence of a low but measurable amount of scission was verified. A mathematical model of the irradiation pr ocess was developed, which gave very good predictions of the measured value s. (C) 1999 Elsevier Science Ltd. All rights reserved.