Structural development during nonlinear free-radical polymerizations

Abstract

Relationships have been derived which describe structural development in nonlinear free-radical polymerizations as a function of conversion. The recursive analysis is based on the assumptions of ideal network formation and those assumptions standard in the kinetic analysis of linear free-radical polymerizations. Significant is the fact that changes in average primary chain length (e.g., due to drift or Trommsdorff effect), which in linear systems give rise to large polydispersities, can be accounted for in these relationships. While it is shown that for many systems such rigor is unnecessary in the pregel regime, it is also shown that neglect of such effects in the postgel regime may lead to serious errors. For the case in which monomer depletion is the only source of a changing kinetic chain length, the gel point is observed to be delayed and the network observed to be looser in comparison with the case in which monomer depletion is neglected.

Stochastic modeling and simulation of photopolymerization process

“…Miller and Macosko [34] developed a model for crosslinking resulting from direct coupling (homopolymerization), direct coupling with propagation, and coupling through copolymerization with small monomers with assuming the initial chains can consist of a random number of repeat units with arbitrary distributions of weight and functionality. Dotson et al [35] derived the weight‐average molecular weight for the crosslinking free radical polymerization by assuming: (1) all functional groups of the same type are equally reactive; (2) reactions are first‐order Markovian; and (3) no intramolecular reactions occur in finite species and derived the weight‐average molecular weight for the crosslinking free radical polymerization and obtained the gel point as the conversion where the molecular weight goes to infinity. Okay [36] also derived an equation to approximate the gel point for the free radical monovinyl‐divinyl monomer copolymerization.…”

Control of network structure in emulsion crosslinking copolymerization

“…Further assume that the kinetics of bulk copolymerization are valid, so that the following considerations are applicable for the seeded operations in the case of emulsion polymerizations. In this case, using eqns (11) and (12), ( Fig. 5.…”

Mathematical Modeling of the Bulk Photopolymerization of Furfuryl Acrylate

“…Besides the theoretical knowledge that can be gained from the modeling of a polymerization system, such studies allow the conditions for obtaining polymers with defined properties to be predicted from the practical point of view 8–32. For example, in the case of FM, it is very difficult to obtain experimentally a proper characterization of the microstructure of its network.…”