Abstract
Sumikathene, Faifax and Marlex, which have different densities and crystallinities, were irradiated by a 1.8MeV electron beam, and the gel fraction for each material was measured. The radiation dosages used were 100Mrad and below.
The gel fraction increased sharply with dosage up to 20Mrad, then it reached a constant value. The ge1 fraction of Sumikathene only reached a saturated value of about 80%, but the fractions of the other two polyethylenes had not yet reached a constant at 100Mrad.
By introducing the factars of crosslinked polyeythylene (crosslinking coefficient α, decay coefficient β), which are functions of irradiation temperature, duration and atomosphere, density and crystallinity of polyethylene, and injected electron energy, a general formula was formed. The results obtained by calculation were very close to the experimental results. By calculation, the crosslinking ratios of Faifax & Marlex reached the values of 83% (at 180Mrad) and 87% (at 400Mrad), respectively. The gel fraction was used for the measurement of the crosslinking ratio.
