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New aspects of unsaturated polyester resin synthesis. Part 2. Reactant sequence distribution and its effect on cure kinetics
Author(s) -
Zetterlund Per B,
Gosden Ray G,
Weaver William,
Johnson Anthony F
Publication year - 2003
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.1129
Subject(s) - phthalic anhydride , maleic anhydride , polymer chemistry , prepolymer , differential scanning calorimetry , materials science , reactivity (psychology) , copolymer , monomer , condensation polymer , polyester , kinetics , styrene , steric effects , chemistry , organic chemistry , catalysis , polyurethane , polymer , composite material , thermodynamics , medicine , pathology , quantum mechanics , physics , alternative medicine
The distribution of unsaturations in the prepolymer of a typical unsaturated polyester (UP) resin (maleic anhydride, phthalic anhydride and 1,2‐propylene glycol) has been shown to influence the kinetics of the cure process with styrene monomer. Segments containing double bonds in close proximity appear to lower the reactivity of the resin due to steric hindrance, as indicated by the fact that the rate of cure and the final degree of cure, measured by differential scanning calorimetry (DSC), increase as the average sequence length (SL) of maleic units decreases. This implies that the reactivity of UP resins may be improved by synthesis of prepolymers with certain reactant sequence‐length distributions. The copolymer formed by the melt condensation process of maleic anhydride, phthalic anhydride and 1,2‐propylene glycol in the absence of a transesterification catalyst has a non‐random structure with a tendency towards blockiness. This was established using 1 H NMR analysis in tandem with deterministic and Monte Carlo modelling techniques. Copyright © 2003 Society of Chemical Industry