Modeling of unsaturated polyester prepolymer structures. I. Chain branches and overall chain end numbers

Abstract

A review on the synthesis of unsaturated polyester (UP) prepolymers showed that Ordelt saturation (reaction of hydroxyl groups with double bonds) is the major effect that may cause formation of chain branches and then result in an uncertainty of chain end number or functionality. A model has been derived in this work to estimate the number of chain branches and the number of chain ends of UP prepolymers from several fundamental molecular parameters, including hydroxyl and carboxyl indexes, Ordelt saturation extent, short-and long-chain branch distribution, molecular polydispersity, and starting reactant composition and also reasonable assumptions concerning the chain-branch lengths. Simulation results were compared with experimental ones. The influences of the mentioned molecular parameters on the chain branches and on the overall molecular chain ends are discussed in this work.

Nanostructuration of Unsaturated Polyester by All‐Acrylic Block Copolymers, 1 ‐ Use of High‐Molecular‐Weight Block Copolymers

“…The characteristics of the different resins and their solubility parameters are shown in Table 1. Throughout the present study, the resins will be denoted as UPx (UP/S 65: 35), where x represents the mol-% of orthophthalic units in the unsaturated polyester precursor. In some cases, some S has been added to the resins up to reach a UP/S mass ratio of 50:50 -UPx (UP/S 50:50) in order to decrease the overall viscosity of the mixtures.…”

“…Molecular characteristics of the P(MMA-co-DMA) random copolymers and the different homopolymers, as determined by 1 H NMR analysis and SEC measurements (based on PS standards). [36] Polymer DMA M n PDI mol-% kg Á mol S1 [34] b) The values in brackets refers to UP precursors only, without S; c) From SEC measurements and based on PS standards; d) As determined by 1 H NMR analysis by comparing NMR spectra before and after styrene removal by evaporation; e) Ordelt reaction is the side reaction between -OH groups and the maleate double bonds during the UP prepolymer synthesis [35] Dynamic Mechanical Thermal Analysis (DMTA)…”

Polymer/clay nanocomposite plasticization: Elucidating the influence of quaternary alkylammonium organic modifiers

“…42,44 Polyesters dispersed with the CTAB organic modifier had higher degrees of maleate-fumarate isomerization, ranging from 50 to 59% fumarate isomers. Without the steric hindrance from the clay fillers, the hydroxy-functional monomers may have exhibited less preference to react with the transisomer.…”

Unsaturated Polyesters and Vinyl Esters

“…A very detailed and exhaustive review on recent developments regarding the chemistry and the analytics of unsaturated polyester resins is given by Penczek [7]. An innovative model to analyze these versatile polymers was developed by Yang and Pascault (1997) [9]. With this method it is possible to evaluate the average number of chain branches and chain ends of UP pre-polymer, but also other fundamental molecular parameters such as the hydroxyl and carboxyl values, the molecular polydispersity, short-and long-chain branch distribution, as well as the composition of the starting reactants.…”