The effect of component addition order on the properties of epoxy resin/polyurethane resin interpenetrating polymer network structure

Epoxy resin (ER) is one of the most important synthetic resins, but it has the disadvantage of lacking impact resistance. However, it can be improved by mixing with polyurethane resin (PU). In this study, Epon 828, triethylenetetramine (TETA), polytetramethylene ether glycol (PTMG), isophorone diisocyanate (IPDI), and dibutyltin dilaurate (DBTDL) were used as raw materials to prepare ER/PU interpenetrating polymer network structures (IPNs) by three different blending processes. The results showed the reactivity between TETA and IPDI were greater than that between TETA and ER. When ER/TETA/PTMG/IPDI/DBTDL were mixed at the same time, or ER and PU resins were prepared separately and then mixed, the ER/PU composites produced had a phase separation inside the structure. The most appropriate blending method was to mix ER with PTMG, IPDI, DBTDL first, and then add TETA after 10 min. The composite formed had a uniform appearance, and had better physical, mechanical, and thermal properties than the others did.