The Structure And Properties Research Of CF/EP、CNTs/EP Composite Materials

For the epoxy resin, which is an important thermoset plastic，and has goodadhesion properties, chemical resistance, etc. we can make it as form coatings,composite materials, casting materials, adhesives, etc. as engineering plastics,composites, construction materials, electronic appliances materials, adhesives,coatings applied to various fields of national economy.Now there is a growing interest in the research field for fiber-reinforced epoxycomposites, and the lighter mass, higher strength depends its widely used inaerospace. Vacuum transfer molding (VRTM) is an important method of moldingfiber-reinforced epoxy composite material, which can ensure the quality of molding, ahigher efficiency and less pollution to the environment.This paper research the two aspects:1, the main assignment was design the vacuumtransfer molding apparatus and process methods, including the choice of EP and acuring agent, the ratio of the design, the curing temperature, vacuum and post-curedof composite materials, etc, and testing of the mechanical properties of the compositematerial. To analyze the impact of the filler on the mechanical properties of thecomposites, we added the CNTs to EP, get the CF/EP(CNTs) composite material.2, we dispersed the carbon nanotubes (CNTs) in epoxy (EP), to study the percolationof CNTs/EP composite. then the EP/CNTs composite sample were cyclic stretched,we studied the conductivity changes from cycle stretch, analysised the distributionregular of CNTs in epoxy. The main findings are as follows:(A) VRTM preparation of CF/EP composites and performance enhancement(1) First, we designed VRTM molding apparatus,compared with the two kinds ofepoxy system（LT5078and E51, according to the experimental conditions and thescanning electron micrographs,we choosed LT5078system as VRTM molding resin,the quality ratio of epoxy resin and curing agent is10:3, room temperature as curingtemperature, time is24h, the post-curing temperature is80℃, the time is3h,vacuum degree of0.1MPa. (2) In order to study the mechanical influence of Nano-filler in CF/EP composite,were added the weight fraction of0.1%and0.5%of CNTs to epoxy resin, preparedby molding VRTM. the comparison of Tensile test as: Comparing with the CF/EP, thetensile strength of the CF/EP(0.1%CNTs) was improved to a certain extent, the tensilemodulus increased19%; the tensile strength of CF EP/(0.5%CNTs) has little change,tensile modulus has22.7%increasing. Also later we sprayed the CNTs to the CFsurface, the thickness of the same carbon fiber layers was increased, making theoverall mechanical properties of the composites decreased.(B)Research the conductivity of CNTs/EP composites(1)The difference dispersion method of CNTs in EP have influence on degree ofdispersion of CNTs in the EP, thus affecting the value of the CNTs in the percolationof the EP. Our testing using ultrasonic solvent mixing, we got the percolation value ofCNTs in EP is0.3%Wt.(2)In order to study the conductivity change in the stretching process, the CNTs/EPwere stretch-revert for10cycles. The results show that the process ofstretching-revert, along with the destruction and restructuring of the conductivenetwork of CNTs, make the CNTs/EP composites conductivity changing occurs. Thisprovides a good experimental basis on the fields of stress sensitive material.