It is desirable to be able to express f as a func- tion of the polymer composition rather than the propagation probabilities used in equation (20). This may be accomplished by making use of the relationsg P2l __ E 3 PI, m2 ... Thus we see that f is expressible in terms of the copolymer composition m2 and the quantity (1 - rlrz) which is a measure of the alternation ten- dency in copolymerization. It is possible, there- (9) rr and rz are relative rates of propagation and ...