Thesis (M.Eng.)--Chulalongkorn University, 1999

The structures and properties of two different types of polyurethane elastomers, moisture cured polyurethane elastomers and two-component polyurethane elastomers, produced from new cyclo-aliphatic isocyanate (norbornane diisocyanate), were studied and compared with the conventional isocyanate-based polyurethane elastomers. For moisture cured polyurethane elastomers, the effects of diisocyanates (norbornane diisocyanate (NBD) and isophorone diisocyanate (IPDI)) and the effects of NCO% were ivestigated. It was found that NBDI-based polyurethane elastomers have higher reactivity and weathering resistance than IPDI-based polyurethane elastomers. IPDI-based polyurethane elastomers have superior mechanical properties and better phase separation to NBDI-based polyurethane elastomers. From the structure analysis, it showed that the hydrogen-bonded urea carbonyl groups of IPDI-based polyurethane elastomers are more than those of NBDI-based polyurethane elastomers. This implies the higher strength in IPDI-based polyurethane elastomer as found in the tensile strength results. Increasing NCO% from 6% to 8% increases the tensile strength, which corresponds to the more amount of hydrogen-bonded N-H groups, hydrogen-bonded urethane and hydrogen-bonded urea groups of polyurethane elastomers at NCO% = 8% than 6%. For two-component polyurethane elastomers, tha effects of diisocyanates (norbornane diisocyanate, isophorone diisocyanate, m-xylene diisocyanate (m-XDI) and toluene diisocyanate (TDI) and the effects of curing agents (ethacure100 and ethacure300) were examined. NBDI-based polyrethane elastomers have higher reactivity and weathering resistance than IPDI-based polyurethane elastomers. IPDI-based polyurethane elastomers have superior mechanical properties and discolouration resistance to polyurethane elastomers prepared from the other diisocyanates (NBDI, m-XDI, TDI). IPDI-based polyurethane elastomers have better phase separation than NBDI-based polyurethane elastomers. Moreover, it was found that IPDI-based polyurethane elastomer is tougher than NBDI-based polyurethane elastomer and the aromatic diisocyanate (XDI and TDI)-based polyurethane elastomers are stiffer than the aliphatic diisocyanate (NBDI and IPDI)-based polyurethane elastomers. Ethacure100-based polyurethane elastomers have superior mechanical properties, higher discolouration resistance and higher reactivity but lower weathering resistance to ethacure300-based polyurethane elastomers.