Thermal, Chemical, and Morphological Characterization of Microcellular Polyurethane Elastomers.

In this study, three different microcellular polyurethane elastomers (MPUE) based on 4,4′-diphenylmethane diisocyanate with different rigid segment contents are prepared (Formulations 1, 2, and 3 with 32, 35, and 42% of rigid segment content, respectively). The MPUE are obtained through a two-step method using a prepolymer system. The samples are analyzed to determine their thermal, morphological, and chemical properties. The thermogravimetric analysis indicates the presence of two degradation stages, referring to the rigid and flexible phases, respectively. The differential scanning calorimetry tests indicate that for the MPUE there was an increase in the glass transition temperature of the flexible phase with an increase in the percent of the rigid phase. An increase in the quantity of the rigid phase present in the MPUE results in greater values for the crosslink density, which in turn results in an increase in the rigidity of the material. The scanning electron microscopy micrographs indicated a large number of closed cells and that a higher rigid segment content give a better cell homogeneity of the samples. [ABSTRACT FROM AUTHOR]