EFFECT OF RESIDUAL AMINE CATALYSIS ON THE THERMAL DEGRADATION OF POLYURETHANE ELASTOMERS

Remarkable reductions in the physical properties of polyurethane elastomers (PUEs) prepared from polymer with 4, 4′-diphenylmethane diisocyanate (MDI) were observed when they were subjected to high temperatures (above 105°C) for long periods of time (400hrs). These results were caused by the fact that PUEs were deteriorated by a decomposition of their left in urethane linkages which resulted from their having been attacked by triethylenediamine (TEDA) residues in the PUE. Deteriorations were observed in the center parts of PUE samples over 1cm thickness. Associated amine degradation products were later detected. Also, urea compounds occuring from the amine degradation in samples thicker than 1cm were determined directly from degraded PUE by FT-IR. By using diethylene glycol and butane diol as chain extender, a new PUE has been developed with reduced hardness. Additionally, the mechanisms causing amine residues to degrade PUEs were discussed.