Comparison of the Dynamic Properties of Solid Polyurethane Elastomers

Abstract

Standard elastomeric formulations are based on three compo nents : a) diisocyanates such as TDI, MDI and NDI b) polyols with an ester, ether, and/or carbonate backbone c) chain extenders that are reactive glycols or aromatic diamines Such standard formulations were subjected to dynamic tests to determine their relative load bearing capacities (constant load testing methods were gen erally used). These results could be correlated to a certain extent with rou tinely measured mechanical properties. The behavior of materials chain extended with aromatic diamines (polyurea urethanes) was somewhat different from the glycol-extended systems. The poly urea urethanes have a high softening temperature, show little thermoplasticity and a relatively high set after testing. Glycol-extended systems showed rela tively little set after deformation, but the softening temperature of such elas tomers are relatively low. Although the investigated system could be manufactured in a wide hardness range, the optimal dynamic properties were usually found only in a very nar row hardness range. The optimal results were obtained with NDI as diiso cyanate and 1,4-butanediol as extender.