A DIELECTRIC STUDY OF MOLECULAR RELAXATION IN LINEAR POLYETHYLENE

Although the dielectric beta glass-rubber relaxation has previously be en observed in dipole-decorated branched polyethylenes and in linear p olyethylene containing several mole per cent chlorine, it has not been observed in linear polyethylene containing very low dipole concentrat ions. Dielectric relaxation has been studied here in a linear polyethy lene specimen (containing a few carbonyl groups per 1000 methylene uni ts) in the hope of observing the beta process. The isochronal loss pea k for the beta relaxation is not well resolved from that for the alpha relaxation. However, it is found that the beta process is very appare nt as an increment in the isochronal dielectric constant scans. This w as taken advantage of in characterizing the relaxation. In comparing t he results with previous work it is found that there is a progression in the beta relaxation T(max) location towards higher temperature as t he degree of crystallinity increases through branched and linear polye thylene specimens.