To improve thermal, mechanical and adhesion properties, epoxy resin was modified with methyl phenyl silicone (MPS), acrylonitrile butadiene styrene (ABS) and graphene oxide (GO). In order to increase compatibility and stability, MPS intermediate was grafted on epoxy resin through condensation reaction. Transmission electron microscopy images showed well dispersion of GO particles in the system proving successfully preparation of the MPS grafted epoxy/ABS/GO nanocomposite. Single lap shear strength for steel‐epoxy/carbon fiber composite joint in sample containing 15% MPS and 2% ABS improved up to 108% compared to neat epoxy. Such an improvement occurred when only 5% MPS, 2% ABS and 0.1% GO were used showing GO could decrease required content of modifiers in this case. Tensile strength of sample containing 5% MPS and 2% ABS was 49.89 MPa and it reached 55.23 MPa by adding 0.1% GO while it was 37.12 MPa in pure epoxy. Nanocomposite modified sample had a residual char of 20 wt%. at 600°C and increment of 30°C in initial degradation temperature and 7°C in maximum degradation temperature compared to pure epoxy. These finding beside 23% increasing in calculated activation energy using Kessinger's and FWO method's proved significantly improved thermal stability of modified epoxy resin. Scanning electron microscope images of fractured surface of specimens showed micro size domains obtained by phase separation cause toughness improvement and crack energy absorption.
In this study, non‐isothermal curing kinetics of the prepared samples was studied using differential scanning calorimetry (DSC) to evaluate the effect of methyl phenyl silicone resin (MPS), acrylonitrile butadiene styrene (ABS), and graphene oxide (GO) on the cure reaction of epoxy resin. Chemical and microscopic structure of prepared nanocomposites was investigated using Fourier‐transform infrared spectrophotometry (FTIR) and scanning electron microscopy (SEM), respectively. Izod impact strength of modified epoxy resin with 5 phr MPS, 2 phr ABS, and 0.1 phr GO was about 53% higher than pure epoxy resin. Evaluation of activation energy (Ea) by Kissinger, Ozawa, FWO and Friedman methods showed that the presence of GO facilitates the curing reaction by reducing Ea about 30% which is due to the catalytic effect of hydroxyl groups presented on the surface of GO for epoxy ring opening. According to Friedman's plots, curing reaction remained autocatalytic for all of samples. The presence of GO increased the autocatalytic term of the reaction (n) from 0.26 to 0.32. Non‐isothermal DSC diagrams obtained from experimental data fitted well with data obtained from theoretical relations.
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