Effect of temperature on the mechanical behavior of the CNT reinforced epoxy

Abstract

In this thesis, the effect of temperature on the mechanical behavior of CNT reinforced epoxy has been investigated. The first step for this research will be to produce SWCNT - epoxy and MWCNT - epoxy in the lab in the forms of plates with 0.5, 1, and 1.5 wt. percent of CNT concentrations. After the plates are ready, the next step was to put the plates in thermal chamber to perform thermal cycling tests. Each thermal cycle would be to heat the plates from room temperature to 0.85Tg which is 85 percent of the epoxy glass transition temperature (Tg). The glass transition temperature of the epoxy was determined in the lab using DSC. For measuring the mechanical behavior of the plates, shear - beam test and tensile test were used. The process would be to measure the mechanical properties of the plates at 0 cycles (as fabricated) and after 1500 and 3000 exposure to the mentioned thermal cycles. The short beam test and tensile test can measure the interlaminar shear strength and tensile strength of the plates, respectively. Based on these data, the model for changing the interlaminar shear strength and tensile strength of the plates with increasing the thermal cycles can be developed. Furthermore, in this research, the tensile strength, ultimate strain, and Modulus of Elasticity of epoxy, and carbon nanotube reinforced epoxy while they are exposed to different thermal cycling environments are obtained.Thermal cycling environments can exist in many conditions such as in earth orbit for satellites which rotate around the earth and pass through the sun illumination and earth's shadow, and for airplanes which fly in different altitudes with different temperatures. Carbon nanotube reinforced epoxy is one of the nano - composite materials which have been broadly used in many applications such as aerospace, automotive, electronics, and other industries. The reason for using this material as a promising nano – composite in many industries, is its mechanical properties such as high strength, stiffness, and flexibility. The goal in this experiment is to fabricate the nano – composite and expose it to different thermal cycle numbers to monitor the changes in tensile strength, ultimate strain, modulus of elasticity, and shear strength. For this purpose, tension and short – beam tests were applied. Using the results obtained with this experiment, the mechanical behavior of nano – composites with different carbon nanotube concentrations are analyzed and discussed. Furthermore, based on this analysis, conclusions are included in the conclusions section of this research.