New aspects of unsaturated polyester resin synthesis. Part I: modelling and simulation of reactant sequence length distributions in stepwise polymerization

Abstract

The quantification of the relationship between physical properties of polymeric products and the sequence distribution of comonomer units in a polymer chain is not an easy task. In this work, detailed consideration is given to the sequence lengths and sequence length distributions to be expected in unsaturated polyesters formed by the reaction of maleic anhydride, phthalic anhydride and a diol, a reaction which gives rise to the low molecular weight precursors used in unsaturated polyester resins. Monte Carlo methods are used to explore the effects of rate constants, reactant stoichiometry and extent of reaction on the microstructure of the chain. Attention is also given to structural asymmetry of the diol component and the influence of the dynamics of the ring opening of the anhydride coreactants on the products. The approach is generic and can be readily adapted for any copolymerization which proceeds by a stepwise kinetic mechanism.© 2003 Society of Chemical Industry

A general kinetic method to predict sequence length distributions for non-linear irreversible multicomponent polymerizations

“…Based on the selective acid hydrolysis [13] of polyesterepolyurethanes and using size-exclusion chromatography (SEC) as a subsequent analytical technique, it is possible to measure the SLD of this family of polymers [14,15]. Sequence length distributions were also studied in the production of unsaturated polyesters formed by the reaction of maleic anhydride, phthalic anhydride and a diol [16]. Recently, the presence of microphase separation between hard microdomains and a soft segment matrix for polyurethaneeurea copolymers based on ethyleneebutylene soft segment was experimentally established [17].…”

Addition‐Fragmentation Chain Transfer to Polymer in the Free Radical Ring‐Opening Polymerization of an Eight‐membered Cyclic Allylic Sulfide Monomer

“…transesterification of polyesters. [1,3,4] This ''reshuffling'' of the chain-length distribution of linear polymer(s) ideally results in the MWD approaching the most probable (Schulz-Flory) distribution. [1,2,5] Free radical ring-opening polymerizations have received considerable attention as a means of reducing the level of shrinkage normally associated with free radical polymerization.…”

“…It was suggested that interchange reactions analogous to those in polyester [3,4,17] and polyamide [18] systems may occur in case of the eight-membered disulfide monomer, 2-methyl-7-methylene-1,5-dithiacyclooctane (MDTO). [13] The idea of these interchange reactions was put forward based on the finding of bimodal MWDs, which were speculated to originate from backbiting via addition of the propagating sulfur radical species to one of the double bonds on the polymer backbone, with subsequent b-fragmentation (i.e.…”