Preparation and performance evaluation of electrothermal actuators using aligned carbon nanotube reinforced epoxy composites

Abstract

By using an aligned multi-walled carbon nanotube (MWCNT) reinforced epoxy composite, an electrothermal bimorph actuator was fabricated and its load and deformation capacities were investigated. The composite has a negative coefficient of thermal expansion (CTE) as well as large Young’s modulus. To evaluate the actuator property, a composite/aluminum laminate was prepared and a U-shaped actuator was formed by cutting off the middle part of the composite/aluminum laminate. The Young’s modulus of the composites increased linearly with increasing MWCNT volume fraction, and that of the composite containing 27 vol.% MWCNTs reached 56.8 ± 3.9 GPa. We also demonstrated that the actuator showed a large bending displacement and force output under low voltage stimulation. The bending displacement and force output of the actuator with the free length of 16 mm reached 7.6 mm and 9.0 mN under a DC voltage of 5.2 V, respectively. Furthermore, the actuator fabricated in this study showed higher values of work output per unit volume compared to the actuators reported in previous studies within the frequency between 0.05 Hz and 0.5 Hz. The enhanced performance was attributable mainly to the high Young’s modulus of both composite and aluminum layers and the huge mismatch of the coefficient of thermal expansion in the composite/aluminum laminate.

Keywords

• carbon nanotube
• composite
• young's modulus
• coefficient of thermal expansion
• actuator