. "ylene radicals relative to the other alkylene radicals being such that the ratio of carbon atoms to oxygen atoms in the total OR blocks ranges from 2.3:1 to 2.8:1, m has an average value from 7 to 100, A is a radical selected from the group consisting of the --OR', --OOCR' and ##STR4## radicals wherein R' is a radical free of aliphatic unsaturation selected from the group consisting of hydrocarbo" . . .