RADIATION CROSS-LINKING OF PVC COMPOUNDS WITH SURFACE-TREATED CALCIUMCARBONATE

PVC compounds with surface-treated CaCO3 were prepared and irradiated by Co-60 gamma-rays under nitrogen atmosphere and in the presence or a bsence of trimethylol propane trimethacrylate (TMPTMA). Samples withou t TMPTMA did not respond to irradiation. The mechanical properties of other samples, such as tensile strength, yield strength, and % elongat ion, were affected and one was found to,be most sensitive to irradiati on. Lower values of Young's modulus were observed for samples irradiat ed in air compared with samples irradiated in nitrogen at lower doses, indicating the effect of atmosphere in the range of irradiation studi ed. Mechanical properties and the T(g) were not affected by the presen ce of filler because of weak adhesion at the polymer-filler interface. Inverse gas chromatography showed both the CaCO3 and the PVC to be ac ids, accounting for these observations. The weak interaction also expl ains the lower values of Young's modulus for samples using surface-tre ated CaCO3 as compared with uncoated CaCO3.