EB crosslinking of polyethylene ‘O’ rings: Optimisation of process parameters

Abstract

Radiation crosslinked LDPE ‘O’ rings, an inexpensive substitute for PTFE and polysilicone gaskets in high temperature applications, are widely used in the industry. Radiation crosslinking of LDPE ‘O’ rings, in the finished form was carried out at the 20 kW-2 MeV, ILU — 6 type EB facility installed at the Bhabha Atomic Research Centre, Bombay to establish irradiation technique for large scale production and for an adequate and uniform dose delivery. Two irradiation geometries viz. flat bed and rotating spindle were chosen for batch processing and optimisation of process parameters. The laboratory analysis and thein situ performance showed that a minimum of 65 % gel-content is needed in the irradiated rings and that an absorbed dose of about 200 kGy is adequate to meet the industrial standards. Rotating spindle technique was found to have an edge over flat bed irradiation in terms of dose uniformity and throughput. This paper gives an account of the work carried out to optimise the process parameters for both the geometries.