Preparation and properties of grafted and non-grafted polyurethane/epoxy resin interpenetrating polymer networks

Grafted and non-grafted polyurethane/epoxy resin interpenetrating polymer networks(PU/EP IPNs) were prepared by a sequential method,and effect of different PU/EP mass ratio on mechanical and thermal properties of these two types of IPNs was investigated.FT-IR analysis confirmed the formation of carbamate grafted structure within grafted PU/EP IPNs via a reaction between —NCO of polyurethane and —OH of epoxy resin.Results of mechanical properties test indicated that incorporation of polyurethane pre-polymer into epoxy resin could significantly improve the materials' mechanical performances: when the mass ratio of PU/EP was 15/85,grafted PU/EP IPNs' tensile and impact strengths reached their maximums,which were 36.7MPa and 22.39kJ/m2,respectively;while PU/EP's mass ratio was 10/90,non-grafted PU/EP IPNs achieved its optimal tensile and impact strengths,which were 27.8MPa and 19.34kJ/m2,respectively.TG analysis shows that grafted PU/EP IPNs obviously exhibited a better thermal stability than non-grafted IPNs.