Stabilization of poly(vinyl chloride). II. Stabilization mechanism through metal soaps by complementary color action

In a previous paper, it was pointed out that the stabilization mechanism through metal soaps might be affected by an effect of complementary color. In this work, the colors of heated poly(vinyl chloride) (PVC) films mixed with various metal soaps were investigated by using a differential colorimeter and a spectrophotometer. Monochromatic coloration was observed with PVC, PVC–Ca stearate, and PVC–Ba stearate systems. On the other hand, the phenomenon of color mixing was observed with PVC–Zn stearate, PVC–Cd stearate, PVC–Zn/Ca stearate, and PVC–Cd/Ba stearate systems. In particular, achromatic color remained with PVC–Zn/Ca stearate and Cd/Ba stearate systems for longer heating periods. This means that the stabilization mechanism for PVC compounded with metal soaps should be effected finally by subtractive complementary colors situated between polyene color and the color effected with the metal complex, in addition to being subject to the usual chemical stabilization mechanisms.