Continuous UV irradiation process for producing low-creep polyethylene

grantor: University of TorontoThe effect of processing variables on continuous uv irradiation cross-linking of polyethylene, (and to a much lesser extent, polystyrene) was investigated. The process included extrusion, melt drawing for orientation, and finally uv irradiation. Benzophenone (BP) was used as a photoinitiator and triallyl cyanurate (TAC) as a cross-linking agent. Creep reduction in the final product was the performance property of interest. Three specific objectives were accomplished: development and assessment of experimental techniques needed for the investigation; assessment of the effect of processing variables on unoriented polymer rod where flexural creep reduction is desired; and assessment of the effect of processing variables on oriented polymer wire where tensile creep reduction is desired. The experimental techniques developed and assessed included: continuous uv irradiation; methods of measuring gel content, cross-link density and additive concentration; extrusion for additive incorporation; methods for both flexural and tensile creep measurement. A factorial experiment was used to screen irradiation variables. Unoriented polymer rods were extruded and irradiated. These included rods of polyethylene and polystyrene. The above mentioned experimental techniques were applied with the flexural creep performance property being a primary interest. Extruded, oriented and uv irradiated polyethylene wire was examined using the above mentioned experimental techniques. Five different types of high density polyethylene were included. (Abstract shortened by UMI.)M.A.Sc