Mechanodegradation and stabilization of polyvinyl chloride during vibromilling

The color development of polyvinyl chloride (PVC) during vibromilling and i ts mechanism, as well as the stabilization method, were studied. Investigat ions showed that the color development of PVC resulted from its dehydrochlo rination reaction, which was caused by the existence of unstable structural defects in the molecular structure of PVC and gross heat generation at the contact interface due to the dissipation of high-frequency impact energy d uring milling. Three often-used heat stabilizers of PVC-barium-cadmium, lea d sulphate, and bis(sulphoisoactyl glycollate)di(n-octyl)tin-were not very effective in preventing color development of PVC during vibromilling. A new stabilizer, designated as VSG96, was developed that was designed to guaran tee that PVC sample retain its original color and chlorine content after it had been vibromilled for 120 hr or more.