Study of the properties and structures of polyurethane elastomers synthesized from norbornane diisocyanate

Abstract

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.