Thermal degradation of poly(vinyl chloride) plastigels

An emulsion, poly(vinyl chloride) (PVC), was analyzed for its components and was used in the preparation of flexible PVC plates utilizing sol-gel processing technology. PVC contained an ether-soluble fraction having carboxylic acid carbonyl groups, a tetrahydrofurane (THF)-insoluble fraction having -COO- groups, and 0.15% aluminum. PVC was mixed with dioctyl phthalate (DOP) in a 0.3-0.8 DOP/PVC weight ratio and heated at 180 degrees C for gelation. The yellowness index (YI) and tensile strength of the plastigels were increased with both heating time and DOP concentration. Infrared (IR) spectroscopy showed that the thermal oxidation and volatilization of DOP occurred simultaneously with dehydrochlorination of PVC upon heating of the plastigels. Agglomeration of PVC particles on mixing with DOP at low DOP levels caused longer gelation times than expected. (C) 1998 John Wiley & Sons, Inc.