Gas‐filled polymers. III. Mechanical behavior of polycarbonate and poly(vinyl chloride)

Gasification behavior and its effects on mechanical properties were determined for amorphous polycarbonate (PC) and poly(vinyl chloride) (PVC). Nitrogen‐gasified PC and PVC exhibit interior regions containing gas bubbles surrounded by surface layers of void‐free polymer, while in the helium‐gasified polymers no gas bubbles could be observed. Scanning electron microscope (SEM) observations of the bubbles in nitrogengasified PC indicate that the bubble walls are smooth and featureless (in contrast to the diffuse walls with fibrils of polymer extending into the bubbles observed previously in gasified polyethylene). For both PC and PVC, neither the yield stress nor the elongation to fracture showed any appreciable variation between gasified and ungasified material. The lack of a significant effect of gas bubbles on the drawing behavior in these glassy polymers stands in contrast with the pronounced effect noted with semicrystalline polyethylene. The origin of this difference in behavior and its relation to the crystallization process in polyethylene are discussed.