Study On The Influence Mechanism Of Polyurethanegrafted Epoxy And Carbon Nanotubes On The Mechanical Properties Of Epoxy Composites At Room Temperature And Low Temperature

Resin based carbon fiber composite materials have high modulus,high strength,light weight and other excellent mechanical properties show a wide range of application prospects.In recent years,due to the rapid development of aerospace and other fields of technology,its composite properties of carbon fiber reinforced resin composite materials also put forward higher requirements,especially resin matrix in low temperature conditions,low temperature performance is more stringent The request.In this paper,the structure-controllable polyurethane-modified epoxy(HPU-EP)was successfully prepared by chemical grafting method,and the effective toughening of epoxy resin for composite materials was realized.On this basis,the HPU-EP The mechanism of MWCNTs on the mechanical properties of epoxy composites at room temperature and low temperature provides the basic data and theoretical support for the preparation of high performance composites.The main work is as follows:Polyurethane prepolymers with the main chain end groups of-NCO were synthesized by using monomers such as polyether polyols and isocyanates,and then the polyurethane(PU)was chemically grafted onto the main chain of epoxy.Epoxy(HPU-EP).The molecular structure of the modified epoxy resin was characterized by FT-IR.The results showed that the segment of polyurethane(PU)was successfully grafted onto the epoxy molecular chain.The molecular weight and its distribution were characterized by GPC.Indicating that the molecular weight of the synthesized product is controllable;The effects of HPU-EP content on the mechanical properties of epoxy resin at room temperature and low temperature were systematically studied.The results show that the overall mechanical properties of the epoxy resin matrix can be improved to some extent under the condition of room temperature and low temperature,especially in the low temperature condition.Tough effect.When the mass fraction of polyurethane modified epoxy resin is 30%,the composite material exhibits the best comprehensive performance,and its tensile strength increases by 12.5%and 29.3%at room temperature and low temperature at 77K,respectively The intensity also increased by 30.8%and 62.3%respectively.The prepared modified epoxy resin has many potential applications in the low temperature resistant resin system and composite material for liquid molding process.The effects of MWCNTs content on the mechanical properties of epoxy resin at room temperature and low temperature were systematically studied.The results show that the mechanical properties of the whole resin system will increase first and then decrease,and the main mechanism of low temperature is that the uniform addition of nano-particles reduces the crosslinking density of the system,Force can form a hole structure,can effectively lead to more cracks and passivation of the growth of cracks in order to absorb the impact of energy to increase the low temperature performance,but the content will appear too much reunion,the performance of the entire system will be affected.