BE-13 Renovation: Lining with Cured-In-Place Pipes - Processes - v01

Heat-Initiated Curing / Hot Curing

Curing of Unsaturated Polyester Resins

Unsaturated Polyesters are formed by polycondensation reaction and dicarboxylic acids. Properties of the final cured UP resin can be influenced by variation of the raw materials, utilized for the unsaturated polyester (e.g. toughness, chemical resistance, strength, reactivity, degree of crosslinking). The unsaturated polyesters are mixed with unsaturated monomers, e.g. styrene, yielding the UP resin. The styrene content of common UP resins is 30 % - 40 %. A too high styrene content will lead to a decrease of strength in the cured final part. UP resins are cured with free radicals, resulting from decomposition of organic peroxides [Pergan2016].

The organic peroxides decompose either by the influence of heat (heat-initiated curing / hot curing) or by the influence of appropriate accelerators (ambient cure / cold curing). The unsaturated polyester molecules polymerize with the styrene resulting in a three dimensional tough network (so called duromer or thermosetting material) [Pergan2016].


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