Influence of Hard Segment in Various Polyurethanes on Physical Properties of Epoxy Resin

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  • エポキシ樹脂の物性におけるポリウレタンハードセグメントの影響

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It is common knowledge that the hard segment in polyurethane extensively influences the physical properties, therefore the aim of this study is to clarify the improvement effect of fracture toughness of cured epoxy resins added polyurethanes having hard segment.Polyurethaneprepoymors having hard segment were synthesized with two kinds of macroglycols (Mn=2000, Polyoxypropylene glycol: PPG, Polycarbonate glycol: PCG), diisocyanate (MDI) and 1,4-Butanediol (1,4-BD), and at the final step the respective polyurethaneprepolymers were reacted with bisphenol-A type epoxy resin with monofunctional hydroxyl group.The epoxy resin terminated polyurethenes (ETPU-Btype) were added to typical bisphenol-A type epoxy resin and cured by adipic acid dihydrazide (ADH).The relationship between properties of cured epoxy resins and hard segment was investigated by comparing with the properties of non-hard segment type (ETPU-N type).All ETPU-B type showed higher improvement effect than ETPU-N type.Regarding bending modulus PPG-B system (P2B system) and PCG-B system (C2B system) showed the higher modulus at over 30phr than the corresponding ETPU-N types.It was observed that C2B system showed the higher fracture toughness than C2N system and kept the relative high value even at 50phr.Similarly P2B system was superior to P2N system, but the fracture toughness at 50phr was observed a significant decrease.The results of scanning electron microscopy (SEM) indicated micro phase separation structure in all ETPU.ETPU-B type presented the uniform distribution of finer particles than ETPU-N type.It can be concluded from the results that the systems which showed high fracture toughness indicated micro phase separation with the finer particles.This suggested that hard segment in polyurethane contributed to the formation of valuable morphology.

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