Design of epoxy modified recycled rubber-based composites: Effects of different contents of nano-silica, alumina and graphene nanoplatelets modification on the toughening behavior

Multifunctional composite materials are recently drawing attention in many field including automotive, aeronautic and transport. The primary goal of this work is to propose low-cost and lightweight material for the automotive industry. In this study, recycled rubber-based composites were developed by using low cost manufacturing methods. At the beginning, recycled rubbers were devulcanized by microwaves to improve the bounding quality with the epoxy. Then, fine particles of recycled rubbers and solid epoxy were mixed together. After incorporating and rigorously distributing various contents of graphene nanoplatelets (GnPs), silica and γ-alumina particles in the matrix, hot compaction was used to manufacture the composites. As the second objective of this study, effect of reinforcement 5-10-15 wt. % of silica, and various contents of GnPs and γ-alumina particles on toughening was examined. In this regard, notched specimens were used to determine critical stress intensity factor and critical strain energy release rate. Fracture toughness showed some fluctuations by the incremental quantity of the reinforcements. Moreover, flexural strength and elasticity modulus were calculated by means of bending tests (three-point, 3PB). Positive effects of reinforcements on elasticity modulus were observed by 3PB tests. In addition, Charpy impact tests were done to assess energy absorbing capacity of the composites. To check the dispersion quality and to identify toughening mechanisms, scanning electronic microscopy was used. The main toughening mechanisms in these composites were identified as crack pinning, crack deflection shear band formation as well as. Finally, wear resistance of the specimens was assessed by macro-scratch tests.