The use of SSA fractionation to detect changes in the molecular structure of model

CLAUDIO J. PÉREZ; N. VILLARREAL; J.M. PASTOR; M.D. FAILLA; E.M. VALLÉS; J.M. CARELLA

POLYMER DEGRADATION AND STABILITY

ELSEVIER SCI LTD

Año: 2009 vol. 94 p. 1639 - 1645

0141-3910

Four model ethylene–butene copolymers of different molecular weights modified with various concentrations of peroxide were analyzed by a DSC based successive self annealing method. The original copolymers had the same intra and intermolecular homogeneous branching distribution along the linear chains with approximately 2.4% mol of ethyl branches. The copolymers with average molecular weights of 29,000, 45,000, 81,000 and 125,000 g/mol were modified with different amounts of 2,5-dimethyl-2,5- di(tert-butyl peroxy)-hexane (DBPH) as a crosslinking initiator. The molecular changes induced by the reaction with the peroxide affect the semicrystalline structure of the material. Variations in the crystal thickness distributions of the material as a consequence of the modification are related to the peroxide induced free radical reactions.