WIT Press

Ageing Mechanism Of Ortho-phthalic Anhydride Unsaturated Polyester Resin


Free (open access)





Page Range

355 - 364




674 kb

Paper DOI



WIT Press


W. Yunying & M. Jiangyan


This paper presents the accelerated ageing test results of a durability study on polyester and analyses the ageing mechanism of this material. Pure resin specimens were cast and exposed in a xenon arc lamp ageing cell or a thermooxidation ageing cell, or were subjected to natural exposure ageing in the western China exposure zone. The chemical groups, morphology, Yellowness Index (YI), gloss, and mechanical performances of the specimens have been investigated. The results showed that the specimens turned yellow, some cracks appeared on their surfaces, and their mechanical strengths first increased and then decreased during the course of ageing. In the early stages of the ageing period, the polyester undergoes post-cure and physical ageing, whereas after a longer ageing period it undergoes some degree of degradation under the synergistic impact of UV, high temperature, and O2. The main influencing factor leading to the failure of the polyester is UV irradiation. Keywords: unsaturated polyester (UP) resin, artificial thermo-oxidation ageing, artificial xenon arc lamp ageing, exposure ageing, synergistic impact. 1 Introduction General purpose unsaturated polyester, that is, ortho-phthalic anhydride-type resin, is one of the most commonly used thermosetting resins, which has the trademark 191#. It is a condensation polymer made from maleic anhydride, ophthalic anhydride, and propylene glycol, to which a certain amount of styrene monomer is added as a thinner/curing agent [1]. Unsaturated polyester resin and its composites are widely used in various fields, such as adhesives, blades for wind turbines, construction structures, boat hulls, etc. Studies on the exposure of


unsaturated polyester (UP) resin, artificial thermo-oxidation ageing,artificial xenon arc lamp ageing, exposure ageing, synergistic impact