Studies on thermal and mechanical properties of carbon nanofiber/multiwall carbon nanotubes reinforced epoxy adhesive based joints

Abstract

Untreated and acid-treated multi-walled carbon nanotubes (MWCNTs) were fabricated using cobalt catalyzed Chemical Vapour Deposition (CVD) process to prepare fillers for reinforcement of epoxy adhesive. Ultrasonic dual mode mixing (UDMM) process via ultrasonic vibration along with magnetic stirring was used to reinforce epoxy adhesive by CNTs. Epoxy nanocomposites containing 0.5, 1.0 and 2.0 wt% of untreated CNTs were produced. The untreated and treated CNTs were characterized using FESEM and EDAX analysis. The thermal and mechanical properties of untreated CNTs reinforced epoxy nanocomposite were studied using Differential thermal analyzer/Thermo-gravimetric analyzer (DTA/TGA) and FESEM. The thermal properties of neat epoxy and epoxy nanocomposites in terms of glass transition temperature (Tg), decomposition temperature and Integral procedural decomposition temperature (IPDT) were studied. The mechanical properties of neat epoxy and epoxy nanocomposites in terms of tensile strength, elastic modulus, fracture toughness and fracture energy were studied. The FESEM and EDX analysis of the carbon nanoforms show the presence of both carbon nanotubes (CNTs) and carbon nanobeads. The DTA/TGA studies revealed that CNTs reinforced epoxy nanocomposite can produce a 13 °C increase in Tg compared to the neat epoxy adhesive. The thermal stability and Integral Procedural Decomposition Temperature (IPDT) values also showed a steady increase till 2 wt% CNTs loading. The tensile test results showed that both tensile strength and elastic modulus increased with higher CNT loading percentage and showed the maximum strength enhancement for 2 wt% CNTs loading. The fracture toughness results showed a significant improvement in KIC value for 1 wt% CNTs loading. The fracture surfaces of the nanocomposite samples were analyzed using FESEM.