Synthesis and application of a novel 5-hydroxymethyl resorcinol diglycidyl ether-terminated polyurethane

Epoxy resin containing active hydroxymethyl group, 5-hydroxymethyl resorcinol diglycidyl ether, was synthesized to produce 5-hydroxymethyl resorcinol diglycidyl ether-terminated polyurethane (ETPU1000). The synthesized epoxy resin is a small monomer molecule, and no polymer is produced during the synthesis process. A monomer contains one hydroxyl group, and more flexible polyurethane segments can be introduced into the main chain when synthesizing the epoxy-terminated polyurethane. The synthesis process of ETPU1000 was investigated by FT-IR spectroscopy. The disappearance of NCO peak in the FT-IR spectrum showed that diisocyanate has completely reacted to form ETPU1000. Then, a series of epoxy cured systems were prepared by changing the mass ratio of ETPU1000 and the diglycidyl ether of bisphenol A (DGEBA), and cured with 4,4'-diaminodiphenyl methane (DDM). The effect of the content of ETPU1000 on the thermal properties, mechanical properties and fracture morphology of epoxy cured systems were investigated. The results showed that when the DGEBA/ETPU1000 blends with 75 wt% ETPU1000, impact strength of the cured systems reached 29.6 kJ center dot m(-2), which significantly increased by 176.6% compared to that of neat epoxy. Scanning electron microscopy (SEM) was used to observe the fracture surfaces of cured DGEBA/ETPU1000 blends, which showed obvious ductile fracture characteristics.