Curing kinetic, thermal and adhesive properties of epoxy resin cured with cashew nut shell liquid

• Cashew nut shell liquid (CNSL) can be used as a low cost curing agent for epoxy resin.
• The 40 wt% content of CNSL is optimum to achieve a good network formation of epoxy resin/CNSL.
• Curing kinetic of epoxy resin/CNSL copolymer was simulated favorably by Sestak–Berggren.
• Silica powder was used to improve the adhesion and thermal properties of epoxy resin/CNSL copolymer.

The curing kinetic, thermal and adhesive properties of epoxy resin cured with cashew nut shell liquid (CNSL) were investigated. The CNSL was used as a curing agent for epoxy resin. The epoxy resin cured with 10, 20 30, 40 and 50 wt% of CNSL showed two-stages curing process between 165–170 °C and 230–235 °C. The solvent extraction experiment indicated that the CNSL content should not exceed 40 wt% to avoid the presence of unreacted CNSL. The apparent activation energy (Ea) of 60/40 epoxy resin/CNSL copolymer was obtained from Friedman’s model-free method for both stages of curing process. The kinetic model and kinetic parameters were determined by Málek’s method and the reaction processes was simulated favorably by Sestak–Berggren (SB (m, n)) model. In addition, silica powder was used to improve the adhesion and thermal properties of copolymer. The epoxy resin/CNSL copolymer with 0.5 wt% silica showed a substantial increase in the lap shear strength and thermal stability tended to increase with increasing silica content. The epoxy resin/CNSL composite showed a great potential for use as a high performance adhesive with good thermal stability.

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