Microcellular Elastomers by Single-Stage Technology

Abstract

A series of single-stage, ambient cured microcellular polyure thane elastomers, based on liquid methylenebis(phenyl isocyanate), was prepared employing a variety of polyols and extenders at varying isocyanate indices and polymer densities. Significant dif ferences in polymer properties may be obtained by employing various high molecular weight base polyols. However, for any given system, polymer properties can be varied through increasing isocyanate index and polymer density. In general, hardness and strength properties are increased with increasing isocyanate in dices and polymer density, while elongation and cold flexing are decreased. Optimum tear strengths are obtained by using a slight excess of isocyanate required to react with all active hydrogen. These polymers which can be processed on conventional foam metering and dispensing equipment are suitable for energy ab sorbing, abrasion resistant and high flexing applications.