Abstract
UV- curable polyurethane acrylate prepolymers were synthesized from hexamethylene diisocyanate (HMDI). polyols(polypropylene oxitlc biol(PPG)/polytetramethylenc ether glycol(PTMG)/glycerinc(GL) (or ethylene glycol(EG). 2-hydroxyethyl acrylate(HEA), and dibutyl tin dilaurate as a catalyst. The effect of prepolymer type and overall composition of the prepolymerfdiluent on the properties of UV-cured polyurethane acrylate as a function of temperature are investigeted. The gel content of the UV-cured polyurethanc acrylates roached to about 9$0^{\circ}C$, within 1 sec curing. The storage modulus increased with increasing PTMG and GL(or EG) content in mixed polyol PPG/PTMC/GL(or EG). The UV-curried polyurethane acrylate films commonly have two main glass transition temperatures in thin temperature range of -10$0^{\circ}C$~14$0^{\circ}C$. The higher temperature Tg of sample A series almost unchanged around 5$0^{\circ}C$ regardless of the composition of PPC/PTMC. but the lower temperature Tg decreased with increasing PTMG content in PPG/PTMG. These two Tgs of sample B and C series based on PPG/PTHG/GL(or EG) were about talc same regardless of the composition of PTMG/GL(or EG) at the fixed content of PPG. The viscosity of UV-curable polyurethane acrylate decreased tlramatically with increasing trimethylolpropane triacrylate(TMPTA) content antral temperature. and the viscosity of UV-curable polyurethane acrylates containing 20wt% and above of TMPTA was given below 1000cps at $65^{\circ}C$.