RADIATION GRAFTING OF HYDROPHILIC MONOMERS ONTO PLASTICIZED POLY(VINYL CHLORIDE) SHEETS .3. PHYSICAL AND MECHANICAL-PROPERTIES OF MIGRATION RESISTANT SHEETS

Medical grade poly(vinyl chloride) (PVC) sheets were surface modified by grafting a combination of 2-hydroxyethyl methacrylate (HEMA) and N-vinyl pyrrolidone (NVP) or NVP alone using gamma radiation in an effort to retard the migration of the plasticizer from the PVC matrix. Presence of cupric ions at a concentration of 0.005 M was found to be optimal in not only preventing the homopolymerization of the monomers but also producing the highest graft yield at all monomer concentrations used for grafting. The grafted PVC was characterized for its water absorption properties. Surface morphology of the grafted surface was examined using scanning electron microscopy (SEM). PVC sheets grafted on both sides as well as on one side were characterized for their physical and mechanical properties in order to assess their suitability in biomedical applications. While the tensile strength and percentage elongation values of PVC sheets grafted on both sides showed a downward trend with increasing graft yield, these properties were not drastically affected by surface modification on one side only at graft yields pertinent to prevent the migration of the plasticizer. Measurement of Shore A hardness and optical transparency of the migration resistant sheetings showed that such properties were not seriously affected by surface modification thus rendering them suitable for their intended applications.