Thermal Stability in Polyurethane Elastomers

Isocyanurates and crosslinks based on such groups are known to possess the most thermally stable structures as they do not degrade below 270°C. PUs with high isocyanurate group contents, whilst possessing good thermal stability, can also be rigid, hard and sometimes brittle and hence were not suitable for use as elastomers in which flexibility and resistance to 

Crosslink density effects also apply as in most polymers, i.e. increasing crosslinking density increases thermal stability on the basis that more bonds need to be broken before serious network breakage becomes apparent. Selection of the diisocyanate used is also a key factor and it is known that if all other factors are equal then PUs from these diisocyanates follow the following sequence  

Trans-1,4-cyclohexane diisocyanate (CHDI)-based PU elastomers are known to be able to undergo isocyanurate crosslinking, and the procedure will now be described. 

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