Curing of the Unsaturated Polyester with Styrene

Cold curing lo crosslink the polyester at room temperature (cold curing), 10 g of the polyester solution prepared in a) are placed in a small beaker or flat tin can and the components of a suitable redox system stirred in one after the other (on no account at 

After 30-40 min the mixture warms up, indicating that the crosslinking graft copolymerization has begun.The sample gels and after 1 h has become almost solid, most of the styrene having polymerized. 

Hotcuring Jo carry out the crosslinking at higher temperatures (hot curing), 0.1 g of dibenzoyl peroxide is dissolved in 10 g of the polyester solution prepared in a) and heated to 80 °C.The polymerization sets in after a few minutes (gelation) and is essentially complete after 15 min. 

After curing lhe sample obtained by cold or hot curing is not yet fully polymerized and to obtain optimum rigidity, an after-curing treatment is necessary. If it is performed at room temperature it takes 2-3 weeks, at 30-40 °C a few days are sufficient and at 70-80 °C some hours are adequate. 

1 g each of the well-ground samples (see Sect. 2.5.1) obtained by cold, hot, and after curing is boiled with 10 ml of toluene for 30 min, filtered after cooling, and washed with toluene.The samples are thoroughly dried in vacuum at 60 °C and the weight loss is determined.The toluene solutions are dropped into methanol and any extracted polystyrene is precipitated.The swellability of all samples is determined in an organic solvent. 

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