Carbon black reinforced C8 ether linked bismaleimide toughened electrically conducting epoxy nanocomposites

Highlight
• The toughness of the epoxy is improved with C8e-BMI.
• Conduction through ohmic contact chain takes the leading mechanism for electrical conduction instead of tunneling with 5 wt% CB.
• The phase segregation between epoxy/C8 e-BMI improves the toughness of the nanocomposite.
• Both toughening and flexibilization effect is responsible for improvement in impact strength.
• The largest challenge of appropriate balance between the electrical conductivity and mechanical behavior is attained in a cost effective manner.

The present work deals with the toughening of brittle epoxy matrix with C8 ether linked bismaleimide (C8 e-BMI) and then study the reinforcing effect of carbon black (CB) in enhancing the conducting properties of insulating epoxy matrix. The Fourier transform infrared spectroscopy (FTIR) and Raman analysis indicate the formation of strong covalent bonds between CB and C8 e-BMI/epoxy matrix. The X-ray diffraction (XRD) and Field Emission Scanning Electron Microscope (FESEM) analysis indicate the event of phase separation in 5 wt% CB loaded epoxy C8 e-BMI nanocomposites. The impact strength increased up to 5 wt% of CB loading with particle pull and crack deflection to be driving mechanism for enhancing the toughness of the nanocomposite and beyond 5 wt% the impact strength started to decrease due to aggregation of CB. The dynamic mechanical analysis (DMA) also indicates the toughness of the nanocomposites was improved with 5 wt% of CB loading due to the phase segregation between epoxy and C8 e-BMI in the presence of CB. The electrical conductivity was also increased with 5 wt% of CB due to classical conduction by ohmic chain contact.