DEGRADATION AND STABILIZATION OF PVC IN BLENDS

Poly(vinylchloride) (PVC)was mixed with various poly(methacrylate)s, p oly(carbonate)s and polymers containing nitrite groups (poly(acrylonit rile), poly(styrene-co-acrylonitrile), nitrile rubber, hydrogenated ni trile rubber) and/or C - C double bonds(nitrile rubber, high-impact po ly(styrene)). The thermal stability was measured at 180-degrees-C in n itrogen, and the evolved HCl was detected by conductometry. It is show n that the nature of the ester group and the content of nitrile groups and C - C double bonds are the dominating factors for the thermal sta bility of poly(vinyl chloride) in these blends. An influence of the mi scibility of PVC with the various blend components an the thermal stab ility can not be clearly detected. Differential scanning calorimetry ( DSC) was used as a powerful method to study the stabilizer distributio n of heterogeneous PVC/poly(styrene-co-acrylonitrile) and PVC/poly(met hylacrylate) blends. It is shown that the stabilizer can be solubilize d either in the PVC phase(PVC/poly(methylacrylate)) or in both phases of the blends PVC/poly(styrene-co-acrylonitrile)).