KINETIC-ANALYSIS OF COMPETING INTRAMOLECULAR AND INTERMOLECULAR POLYMERIZATION REACTIONS

Kinetic reaction theory was used to model a step-growth, thermoset polymerization of a monomer of even functionality f. Intermolecular additions were represented by second-order and intramolecular reactions were expressed by first-order rate expressions. All functional groups were assumed to react with equal reactivity. Independent variables are degree of polymerization i, extent of cross-linking j, and conversion rho. The normalized rate constant for intramolecular reactions is c. The solution for the normalized population density distribution is P(ij) = f(fi - i - j)![(f - 2)i/2]!/2[(f - 2)i - j + 1]![(f - 2)i/2 - j + 1]!i!j! c(j)rho(i+j-1)[(1 - rho + c)(1 - rho)][(f-2)i-2j+2]/2/(1 + c)fi/2 subject to 0 less-than-or-equal-to j less-than-or-equal-to (f - 2)i/2 + 1 and c greater-than-or-equal-to 0. Formulae for the number-, mass-, and cross-link-average molecular weights were derived.