A series of elastomeric sulphonated polyurethane ionomers based on toluene diisocyanate (TDI) and one of three polyols was studied. These materials contain no chain extender; all elastomeric character is due to ionic aggregation. The choice of cation has little effect on the glass transition temperature of the matrix, which decreases with polyol molecular weight. The rubbery plateau modulus was found to vary with cation and casting solvent due to differing degrees of phase separation between ionic and polyol material. The ultimate properties of ionomers based on poly(tetramethylene oxide) polyols suggest that stress crystallization occurs at high elongations, in analogy with segmented polyurethanes and ionenes. However, the strain required to develop crystallinity varied wth the neutralizing cation, due to relaxation of the matrix chains by ion-hopping, as shown by stress-strain testing and infra-red dichroism data.
All Science Journal Classification (ASJC) codes
- Organic Chemistry
- Polymers and Plastics
- Materials Chemistry