In order to obtain high crosslinking rate, polyethylene has been irradiated with an excimer laser. The effect of irradiation temperature and concentration of crosslinking agent, triallyl cyanurate (TAC) on the crosslinking rate has mainly been studied as well as that of laser wavelength and concentration of photoinitiator, 4-chlorobenzophenone (CBP).
A KrF excimer laser light is employed at an irradiation dose of about 450 J/g (sample weight). The irradiation temperature is varied from room temperature to 170°C, and the concentrations of additives were changed from 0.01 to 1.0% (CBP) and 0.01 to 2.0% (TAC).
The CBP concentration of 0.1% and the TAC concentration of 1.0% and the irradiation temperature 150-170°C, just above the melting point of polyetylene, are found to be the opti-mum condition for high crosslinking rate. Almost twice the overall gel content was observed as compared with the previous result.