Effect of the structure of chain extenders on the dynamic mechanical behaviour of polyurethane

The dynamic mechanical behaviors of polyurethanes with different types of non-linear chain extenders are compared with those of corresponding linear chain extender. The T-g of the soft segment matrix showed much variation depending on the type of the chain extenders. The use of non-linear chain extender results in at least 30 degrees C shift toward the higher temperature compared with the sample with 1,4-butanediol. The softening temperature of the hard segment domains is dependent on the detailed structure of the chain extender. Cyclic chain extender and some chain extenders with pendent groups showed a quite significant increase in the softening temperature and well-developed rubbery plateau regions. In tan delta peaks, the peak representing the soft segment matrix becomes much sharper and larger when non-linear chain extenders are employed. (C) 1999 Kluwer Academic Publishers.