Molecular and optical modifications in poly(vinyl chloride) due to N-phenylmaleimide additives and gamma irradiation

The effects of N-phenylmaleimide (NPMI) concentration and gamma dose on the molecular and optical properties of poly(vinyl chloride) (PVC) have been studied. The results reveal an improvement in the intrinsic viscosity of PVC in the presence of an organic material. The effective concentration that enhanced the intrinsic viscosity, from 1.02 to 1.28, was found to be 10mmol NPMI per 100g PVC. The effect of gamma irradiation on the PVC polymer stabilized with this concentration of NPMI has been studied. Samples from the 0.01g NPMI/1g PVC were irradiated with gamma doses in the range 5-180kGy. It is found that irradiation in the dose range 120-180kGy enhances the intrinsic viscosity of the samples. In addition, the transmission of these irradiated samples in the wavelength range 200-2500nm, as well as any color changes was studied. The color intensity ( E) was greatly increased with the increasing gamma dose, and was accompanied by darkness with a significant increase in the yellow color component.