The aromatic carbonate polymers, also referred to as aromatic polycarbonate resins, are a well known family of available materials which enjoy a variety of applications. These polymers are characterized by good ductility in thinner sections, manifesting high impact strength in articles molded or otherwise shaped from the polymer or blends of the polymer. However, in certain applications where thicker sections are desired, the use of aromatic polycarbonates is limited because the ductility and the impact strength tends to decline with increasing average thickness.
It has been proposed that the resistance of aromatic polycarbonates to environmental stress crazing and cracking can be improved by admixing the polymer with polyolefins and olefin copolymers. Blends of that kind are disclosed by Goldblum in U.S. Pat. No. 3,431,224. In practice, however, it has been found that the use of polyolefins in blends with aromatic polycarbonates is somewhat limited. More specifically, when the polyolefins are incorporated in levels which are high enough to achieve the desired advantage of improved stress cracking/crazing resistance, there is a tendency for the molded part to delaminate in processing.
USPTO Backgrounds
USPTO Backgrounds