Study On Epoxy Resin Modified With Carbon Nanatubes And Polyurethane

Epoxy resin(EP) is widely used in many fields because of its excellent properties. Butits weakness is low toughness and thermal stability. Carbon nanotubes(CNTs) have highmechanical properties and thermal stability. Polyurethane(PU) has high toughness. In thisstudy, we used CNTs and PU to modify epoxy resin to enhance its mechanical propertiesand thermal stability. And we evaluated the mechanical properties and thermal stability ofepoxy-based composites modified with CNTs and PU.We brought an enormous amount of carboxyl groups on the surface of CNTs byoxidizing treatment. Then we prepared CNTs-COOH/EP nanocomposites by addingdifferent content of CNTs-COOH into EP. The result is that CNTs-COOH connects withepoxy resin by covalent bond. When the content of CNTs-COOH is1.5%, the shearstrength and impact strength of CNTs-COOH/EP nanocomposite reach the maximumvalues,18.87MPa and11.56KJ/m~2, increasing by34.21%and104.60%respectivelycompared with the shear strength and impact strength of pure epoxy resin.We prepared hydroxyl-terminated polyurethane using polyethylene glycol (PEG,400)and2,4-toluene diisocyanate (TDI-2,4). Then we prepared PU-EP composites by addingdifferent content of PU into epoxy resin. The result is that PU connects with EP bychemical bond. And when the content of PU is15%, the combination property of PU-EPcomposite is the best. At that time, the shear strength and impact strength of PU-EPcomposite is23.96MPa and15.84KJ/m~2, increasing by70.55%and180.35%respectivelycompared with the shear strength and impact strength of pure epoxy resin. So15%is theoptimal content.We added different content of CNTs-COOH into15%PU-EP to prepareCNTs-COOH/(15%PU-EP) nanocomposites to improve the properties of epoxy-based composite on the basis of15%PU-EP. The result is that CNTs-COOH connect with15PU-EP by chemical bond. When the content of CNTs-COOH inCNTs-COOH/(15%PU-EP) nanocomposites is2%, the combination properties is the best.The shear strength and impact strength are27.08MPa and18.71KJ/m~2, increasing by13.02%and18.12%respectively compared with15%PU-EP, increasing by92.60%and231.5%respectively compared with pure epoxy resin.We add15%PU filled with different content of CNTs-COOH into epoxy resin toprepare15%(CNTs-COOH-PU)/EP nanocomposites. The result is that CNTs-COOH-PUconnect with EP by chemical bond. When the content of CNTs-COOH in PU is3%, theimpact reaches the maximum value,21.15KJ/m~2, increasing by35.23%compared with15%PU-EP, increasing by274.34%compared with pure epoxy resin. When the content ofCNTs-COOH in PU is5%, the shear strength reaches the maximum value,31.69MPa,increasing by32.26%compared with15%PU-EP, increasing by125.39%compared withpure epoxy resin.