Study On The Synthesis And Properties Of EP/PU Modified Materials

EP/PU modified material was prepared by using polyurethane component A and B with low glass-transition temperature and good toughness as raw materials to add into epoxy resin, and its structure and reaction mechanism were characterized by FT-IR. Chose different kinds of curing agents and discussed the influence of curing agent on mechanical properties by mechanics performance testing. SEM was used to observe its microcosmic feature and its heat-resistant property and damping property were studied by TG-DTG and DMA curves.IR analysis showed that polyurethane component A and B were able to cross-linked absolutely with epoxy resins, their compatibility was quite well. The relationship of microcosmic feature and mechanical properties were studied by SEM. It could be found that epoxy resins had obvious brittle fracture but EP/PU modified material happened ductile fracture mainly due to the "flexible segment" of polyurethane increase the entire flexibility of EP. TG-DTG curves showed that compared with pure epoxy resins, thermal decomposition mechanism of modified material did not change, its decomposition peak had increased slightly, heat-stability also had slightly increased.The difference of mechanical properties and damping properties of modified materials with different kinds of curing system was discussed in this paper and the influence of PU content on comprehensive performance of modified materials was analyzed. The result showed that curing agents had notable influence on properties of material. In contrast, T-403 curing system had the best comprehensive performance with the purpose of toughness increasing without strength sacrifice. When we chose T-403 as curing agent, compared with pure EP, the toughness of EP/PU modified materials had significantly increased, the impact strength reached 11.83kJ/m2, had improved 78.4%, and elongation at break also had remarkable increasing, tensile strength and bending strength decreased slightly. At the same time, the glass-transition temperature of modified materials decreased and temperature range which tand was higher than 0.3 widened. PU content had pronounced influence on the mechanical properties and damping properties of modified materials. With the increase of PU content, the impact strength and elongation at break increased, and toughness improved, but tensile strength and bending strength declined slightly; the glass-transition temperature Tg was reduced, loss factor tand increased, and damping temperature range widened. When PU content was 15%, the lowest glass-transition temperature of EP/PU modified material reached 50.8℃, and the biggest loss factor tand was 0.834; when PU content was 10%, the damping temperature range was the most widest.Thus it can be seen that damping property of modified materials was improved significantly, impact strength and toughness increased, and although other mechanical strength slightly decreased, the materials can also meet much demand of various fields.