Intermediate these two extremes are copolyester carbonates, such as those wherein R1 is hydrogen, R3 is a relatively short chain alkyl radical, and R2 is a moderately long chain alkyl radical, which exhibit properties that fall between those described above (e.g., higher Tgs than those of the copolyestercarbonates derived from dihydric phenols wherein R1 and R3 are hydrogen and R2 is a long chain