THE RELATIVE PHYSICAL AND THERMAL PROPERTIES OF POLYURETHANE ELASTOMERS - EFFECT OF CHAIN EXTENDERS OF BISPHENOLS, DIISOCYANATE, AND POLYOL STRUCTURES

摘要

Polyurethane elastomers based on polyols such as polycaprolactone diol of molar mass 2000 and polytetramethylene glycol of molar mass 2000; diisocyanantes such as diphenyl methane 4,4' diisocyanate and dicyclohexyl methane 4,4' diisocyanate; and chain extenders such as bisphenol-A, bisphenol-S, bisphenol-AF, and their brominated derivatives were synthesized. The effects of polyol, diisocyanate, and chain extender on the physical and thermal properties were also studied. The polyurethane elastomers were investigated by X-ray diffraction (XRD), differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis. Their limiting oxygen indexes (LOIs), solubilities, tensile strengths, hardnesses, and elongations were also determined. XRD analyses revealed that all of the polyurethanes were semicrystalline. However, the addition of bromine atoms in the polyurethanes markedly decreased their degrees of crystallinity. The brominated polyurethane elastomers have good flame retardancy, as indicated by large LOIs. All of the unbrominated polyurethanes showed good mechanical properties and high thermal stabilities. Polyurethanes based on bisphenol-S had lower solvent resistance caused by the dipolar nature of sulfonyl groups in the polymer chains. (C) 1997 John Wiley & Sons, Inc. [References: 44]