Premium
Dielectric relaxations of high and low density irradiated polyethylenes
Author(s) -
RibesGreus Amparo,
Calleja Ricardo Diaz
Publication year - 1989
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1989.070380611
Subject(s) - dielectric , materials science , polyethylene , branching (polymer chemistry) , crystallite , polymer chemistry , irradiation , relaxation (psychology) , dielectric loss , low density polyethylene , composite material , analytical chemistry (journal) , organic chemistry , chemistry , psychology , social psychology , physics , optoelectronics , nuclear physics , metallurgy
A systematic study of dielectric spectrum on a series of high and low density commercial polyethylenes has been performed. Every polyethylene was characterized by determination of molecular weight distribution, the number of functional groups: ketone, aldehyde, vinyl, vinylidene, trans ‐vinylene, the fraction crystalline, and the degree of branching. We have observed that both γ and α dielectric relaxations zones are formed by two overlap relaxations which have been labeled γ II , γ I , and α′, and α respectively, in order of increasing temperatures. The intensity of the dielectric spectrum of all polyethylene depends over and above other parameters on the number of the carbonyl groups formed as a result of irradiation. This number is different for every polyethylene even when they receive the same dose of irradiation (20 Mrad). However, the participation of carbonyl groups in the γ I and α′ dielectric relaxations decreases with the total crystalline content of each polyethylene. The α dielectric relaxation position in the temperature axis is governed by the most probable crystallite thickness.