1406. ---------------. [HERINGTON, E. F. G.] Study of the Mechanism of Polymerization Reaction by Means of Size-Distribution Curves. Trans. Faraday Soc., vol. 40, 1944, pp. 236-240; Chem. Abs., vol. 38, 1944, p. 6170.

Return to Abstracts of Literature 1250-1499

Literature Abstracts

Degree of polymerization must be known to obtain information on the mechanism. A great simplification in the theoretical treatment, together with the avoidance of many of the practical difficulties, results if the reaction is allowed to proceed to a small extent (5-10%) preferably in dilute solution. 3 types of distribution curves are distinguished: (1) The molecular yield decreases continuously as the chain length increases; this can be terminated either by monomer formation, disproportionation, or transfer in conjunction with either of these; (2) the curve rises from 0 at very small chain length, passes through a maximum, and then decreases as chain length increases, terminated by some combination of mechanisms; (3) the curve commences at real finite values, passes through a maximum and decreases; may be terminated either by (a) monomer formation, disproportionation or transfer, where velocity of termination/propagation increases with chain length, or (b) transfer and combination occurring at the same time. Distribution curves taken in conjunction with other considerations can extend knowledge of polymerization reactions greatly.