INFLUENCE OF THE MATRIX THICKNESS ON RADIATION-INDUCED GRAFTING OF STYRENE ONTO POLY(ETHYLENE-TEREPHTHALATE) FILMS AND NUCLEAR-MEMBRANES

Radiation‐induced graft polymerization of styrene onto poly(ethylene terephthalate) (PET) nuclear membranes and films was performed by various methods, viz., preirradiation in air and in a vacuum. The grafting yield obtained via the preirradiation in a vacuum was considerably higher than that obtained under the same conditions by preirradiation in air. The higher the average distance between pores is, the higher the grafting yield. But when grafting is performed onto both the membranes with average distance between pores and films with different thickness, the grafting yield passes through the maximum as the thickness increases. When the average distance between the pore walls of a membrane is equal to the film thickness, the grafting rate onto the film is higher than that onto the membrane. This is attributed to growth of the termination rates both the active sites within the polymeric matrix and the growing macroradicals during graft polymerization. Both the processes proceed at the phase boundary. The boundary area increases as a result of chemical treatment in the course of nuclear membrane manufacturing. The values of the characteristic parameter α and the critical thickness for styrene grafting onto nuclear membranes and films have been obtained. Copyright © 1990 John Wiley & Sons, Inc.