Graft Polymerization of a Polymer Matrix: Grafting of Tetrafluoroethylene

Graft polymerization of tetrafluoroethylene on polyethylene preirradiated by γ-rays from a cobalt-60 source at ?196°C has been investigated in the region of PE devitrification. A calorimetric technique made it possible to establish that 1.5-2% of monomer dissolves in the amorphous regions of PE at low temperatures. Efficient grafting proceeds in the temperature range directly adjoining the PE devitrification region. The graft copolymer yield amounts to ca. 1200%. The intensification of grafting is apparently caused by the following: (1) because of previous solution of TFE in the PE amorphous regions and filling of the micropores, the reaction in the initial stage is not limited by diffusion; (2) and the initiation efficiency is increased by slow passage through the PE devitrification region. The breaking strength of the graft copolymer is higher than that for the PE copolymer irradiated by the same dose.