ISOCYANURATE CROSSLINKING AS A MEANS OF PRODUCING THERMALLY STABLE POLYURETHANE ELASTOMERS.

Castable polyurethane solid elastomers (PUS) based on the polycaprolactone and the cycloaliphatic diisocyanate trans 1,4-cyclohexane diisocyanate (CHDI) were synthesised to form two series of PUS: in one series the initially prepared prepolymer was chain extended with 1,4-butane diol whilst in the second series a mixed chain extender system was used. It was discovered that elastomers containing a molar excess of isocyanate which had been cast and initially cured at 120 degree C for 16 h were apparently free from reactive NCO groups and did not emit hazardous fumes when subjected to post-curing or rearrangement by heating to 130 degree C. It is considered that the second in situ crosslinking system consists of isocyanurate type crosslinks.