Rate Constant for Long-Chain Branch Formation in Free-Radical Polymerization of Ethylene

Abstract

Quantitative measurements on the rate constant for long-chain branching in radical polymerization of ethylene have not yet been cited. This paper presents a convenient method of calculating the ratio of the rate constant for long-chain branching to that for propagation, by means of polymerization parameters, average degrees of polymerization (X_n and X_w), and amount of total unsaturation. The results of calculation based on our experimental data show that the activation energy E_trp -E_p, and the activation volume ΔV ^trp _∗-ΔV ∗_p were 3.6 kcal/mole and 24 cc/mole, respectively, in radical polymerization of ethylene. The validity of these values is discussed.