Mechanical Properties Of Epoxies And Carbon Fiber/Epoxy Composites Modified By Nano-particles

With extensive applications of polymer and its composites,the demand for materials that possess the characteristics of high stiffness and strength is increasing.Epoxy resin is commonly considered as a kind of matrix material in fiber reinforced polymer composites because of their excellent properties.However,the further application of epoxy resin is limited due to their nature of brittleness.In order to improve mechanical properties,nano-particles have recently been used as reinforcement.Various types of particles with nanoscale have been developed and then utilized in epoxy matrix to form nanocomposites,which provides a new approach to improve epoxy based nanocomposites for future production with low cost,high performance and multi-function.In this thesis,some mixing methods were used to disperse different nanoparticles in epoxy;the preparation and performance of nanoparticle-filled epoxy composites as well as simulations were investigated here.At the same time,the related strengthening and toughening mechanisms were discussed.Moreover,the influence of nanoparticles on mechanical properties of carbon fiber reinforced epoxy composites was further studied.The detail work in this thesis is shown as following:In chapter 2,the effect of different nano-silica portions on the tensile property of epoxy resin was investigated.Three analytical models were used to obtain the effective elastic modulus of nanoparticle-reinforced composites.Based on Monte-Carlo method,the special program for the automatic generation of 2D random distribution particles without overlapping,was developed for nanocomposite modeling by Python language.And meanwhile,tensile properties of nanocomposites including nanoparticle debonding and matrix crack growth were simulated by using the finite element software ABAQUS.In chapter 3,the effect of nano-silica,nano-clay,liquid rubber(CTBN)and their mixed system on epoxy resin's compressive property was analyzed,by using three different epoxy curing agents(Piperidine,2954 and DDS).Simultaneously,compare the failure modes for three curing systems.In chapter 4,the effect of nano-silica and nano-graphite on the fracture property of epoxy resin was studied.Researches show that rubber elastomer can decrease elasticity modulus,strength and thermo tolerance of epoxy resin,although it may substantially improve its toughness.In the thesis,the effect of different contents of rigid particles on epoxy resin's fracture toughness will be analyzed.In addition,the analysis of the toughening mechanism for corresponding systems for different volume fractions by using scanning electron microscopy(SEM)will also be included.In chapter 5,unidirectional carbon fiber/epoxy composites are generated by vacuum assisted resin infusion molding process(VARIM).In order to analyze compressive and flexural properties of carbon fiber composites and their failure modes,a various amount of nano-silica,nano-clay and liquid rubber(CTBN)are added in to modify epoxy resin matrix.