Again, the effect is unclear above 65 parts per hundred of plasticizer because of the dilution of the resin. The unexpected result here is the shift in the minimum yellowness index with respect to antioxidant concentration and plasticizer concentration. A number of conclusions can be drawn as a result of this study. First, the experiment indicated that the effect of resin molecular weight on gamma stability is negligible. The presence of the proper antioxidant can also improve stability, though harder compounds require more antioxidant to attain the minimum of yellowness index.
Lubricant tends to reduce gamma stability.
Many heat stabilizers will also reduce gamma stability, but use of the proper heat stabilizer will have little or no detrimental effect. Leonard Linsky is group leader of plastics in the same laboratory, where he has worked for more than 40 years. Post them in our Members' Discussion Forums .