Effect of microwave cure on the thermo-mechanical properties of tung oil-based/carbon nanotube composites

Abstract

Tung oil is uniquely reactive among plant-based natural oils due to the series of conjugated carbon-carbon double bonds in its fatty acid chains. These conjugated carbon-carbon double bonds impart a high reactivity towards cationic polymerization in the presence of other reactive co-monomers, such as divinylbenzene and styrene. An impressive decrease in the cure time of tung oil-based thermosets has been achieved when the resins investigated were microwaved in the presence of carbon nanotubes (CNTs). However, the fast cure compromised the overall thermo-mechanical properties of the materials investigated. Microwave power, exposure time, and CNT loading effects have been assessed by means of dielectric analysis (DEA), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and proton nuclear magnetic resonance (1H NMR) spectroscopy of extracts obtained by Soxhlet extraction. Possible reasons were proposed to explain the overall inferior properties observed whenever faster cure rates were achieved.