Nanocomposites of a Cashew Nut Shell Derived Epoxy Resin and Graphene Platelets: From Flexible to Tough

A series of nanocomposites were prepared from graphene platelets (GPL) and a flexible biobased epoxy thermoset matrix derived from cashew nut shell liquid. The loading of GPL in the biobased thermoset matrix ranged from 0.1 to 0.8 wt % and resulted in increased tensile strength and Young’s modulus (17 to 33 MPa and 474 to 1700 MPa, respectively). Increases in mode I fracture toughness for KIC and GIC ranged from 0.6 to 1.9 MPa·m1/2 and 906 to 1734 J/m2, respectively. Furthermore, dynamic mechanical analysis revealed that GPL incorporation resulted in increases in the α-transition temperature (peak of the loss modulus) from 27 to 50 °C and increases the storage modulus from 1000 to 2000 MPa. Also, introduction of GPL increased the onset of degradation (Td3%) for the biobased thermoset matrix by 30 °C. Results of this work demonstrate that incorporation of graphene platelets enhances all measured physical and thermal properties of the cashew nut shell derived epoxy resin and enables higher performance appli...