Preparing Hybrid Nanocomposites on the Basis of Resole/Graphene/Carbon Fibers for Investigating Mechanical and Thermal Properties

In this article, phenolic resin samples of Resole reinforced with carbon fibers and graphene nanoparticles were prepared. Different amounts of graphene (0.5%, 1%, 2%, and 3%) were dispersed in a 50% solution with weight of phenolic resin and ethanol with ultrasonic waves for 10 min with 60% power of the device. After that, hybrid composites containing 50% with weight of carbon fibers were prepared with manual layering method and the samples were baked at 160 degrees C, 120 bar pressure with hot pressing. The morphology and thermal and mechanical properties of the prepared nanocomposites were examined with XRD, FTIR, SEM, TEM, DSC, TGA, and three-point bending tests and the results were compared with adding 1% with weight of graphene to the resulting composites; the modulus and flexural power of the samples rose with 19.5% (38.2GPa) and 8.7% (471MPa), respectively. Also, the shear strength of the sample containing 1% graphene with weight increased with 23% compared to the pure sample. The thermal resistance of phenolic resin/graphene composites showed a significant increase compared to pure resin. For example, in the sample containing 1% with weight of graphene, the observed increase in T-5%, T-10%, and T-d,T- max indices were 12, 30, and 5 degrees C, respectively. The DSC test results indicated that the addition of graphene nanoparticles decreases the enthalpy of the baking reaction and also shifts the exothermic peak to higher temperatures. This can indicate the steric hindrance effect of the graphene sheets during the baking reaction, which is caused with the huge surface area of the graphene sheets.