Crosslinking of polythylene photoinitiated with thioxanthone

The phototransformation of thioxanthone in PE and initiated crosslinking of polymer are studied. The quantum yields of reduced thioxanthone, the yield of crosslinks per initiator molecule during photoreduction, and the maximum crosslink yields under vacuum and in air are measured. On phototransformation of thioxanthone the yield of the gel-fraction and the ratio of the yields of the stable photoproducts in the PE depend on the irradaition intensity, which is associated with the competition between reactions in the dark and photochemical reactions of unstable intermediate products, formed on photo-reduction of the initiator.