2016 Volume 52 Issue 3 Pages 70-76
It is widely well known that epoxy resins modified by polyurethane elastomers indicate superioradhesive properties and fracture toughness. However, the storage modulus and glass transition temperature(Tg)of epoxy resins were decreased under the influence of compatibility between epoxy resinand polyurethane by adding polyurethane elastomers. For the solution of shortcoming, we investigatedto epoxy resins modified by polyurethanes containing high hard segment（PUR）without thedepreciation of thermal properties. PURs with various mole ratios of poly（oxytetra-methylene）glycol（PTMG）, 4,4’-diphenylmethanediisocyanate（MDI）and 1,4-butanediol（BD）were synthesized inepoxy. We examined the relationship between hard segment content of PUR and various physical propertiesof the modified epoxy resin. The adhesive properties and the fracture toughness of cured epoxyresin have improved with the amounts of hard segment content of PUR. Micro phase separationstructure of the sea and island type were observed by scanning electron microscope（SEM）. The particlesize of PUR became minuter diameter in compliance with the increase of hard segment content ofPUR, this phenomenon correlate closely with the tendency of fracture toughness. As the results ofthese examination, epoxy resins modified by polyurethanes containing high hard segment indicatedsuperior physical properties without deterioration of storage modulus and Tg of epoxy resins, in contrastto conventional polyurethanes system.
