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synopsisThe addition of a miscible phthalate polyester to BPA polycarbonate results in a remarkable improvement in stress cracking resistance in strong swelling agents. Comparative measure ments of solvent craze initiation resistance, craze strengths, degrees of swelling, and crystallization behavior have been made. The results indicate that the improvement in cracking resistance probably results from stabilization of the craze fibrils by crystallization of the polyester before and/or during fibril formation.

In recent years only a few totally new plastics have been developed, since suppliers are finding it quicker and less expensive to tailor existing resins to meet the requirements of a specific application by alloying. The properties of an alloy of polycarbonate and a proprietary copolyester have been fully characterized. Thermal analysis shows that the polymers are miscible in all proportions. Transparency, glass transition temperature, barrier properties, tensile, and flexural properties of the alloy all fall between those of the neat components. Certain synergistic properties were observed upon blending the polycarbonate and polyester. The tendency of the blend not to yellow during γ‐sterilization is remarkably better than can be predicted by an additive relationship. Chemical resistance of the blends behaves in a similar manner. The excellent balance of properties exhibited by the blend such as transparency, impact strength, γ‐radiation resistance, and chemical resistance makes it useful in applications such as medical disposables and filter bowls.

Phosphites are a critical component of stabilizer formulations and provide molecular weight and color protection to the polymer. This paper profiles a new phosphite antioxidant whose structure provides a n excellent balance of high activity, hydrocarbon solubility, and excellent handling characteristics. A wide range of performance data is illustrated in polypropylene.