Design of Electrically Conductive Structural Composites by Modulating Aligned CVD-Grown Carbon Nanotube Length on Glass Fibers

Abstract

Function-integration in glass fiber (GF) reinforced polymer composites is highly desired for developing lightweight structures and devices with improved performance and structural health monitoring. In this study, homogeneously aligned carbon nanotube (CNT) shell was in situ grafted on GF by chemical vapor deposition (CVD). It was demonstrated that the CNT shell thickness and weight fraction can be modulated by controlling the CVD conditions. The obtained hierarchical CNTs-GF/epoxy composites show highly improved electrical conductivity and thermo-mechanical and flexural properties. The composite through-plane and in-plane electrical conductivities increase from a quasi-isolator value to ∼3.5 and 100 S/m, respectively, when the weight fraction of CNTs grafted on GF fabric varies from 0% to 7%, respectively. Meanwhile, the composite storage modulus and flexural modulus and strength improve as high as 12%, 21%, and 26%, respectively, with 100% retention of the glass transition temperature. The reinforcing mechanisms are investigated by analyzing the composite microstructure and the interfacial adhesion and wetting properties of CNTs-GF hybrids. Moreover, the specific damage-related resistance variation characteristics could be employed to in situ monitor the structural health state of the composites. The outstanding electrical and structural properties of the CNTs-GF composites were due to the specific interfacial and interphase structures created by homogeneously grafting aligned CNTs on each GF of the fabric.

Controlling the Meso-scale Assembly of CNTs/PBI Interlayers for Toughening of Thermoplastic Composites

“…The D peak was detected at 1344 cm -1 , results from the out-of-plane vibrations of sp 3 atoms, which is an indication of the structural defects of carbon atoms while the G peak was located at 1593 cm -1 , attributed to the in-plane vibrations of sp 2 bonded atoms. The I g /I d ratio was calculated as 1.08±0.04, a similar result obtained by He et al [24] with CVD-grown CNTs on micron-sized glass fibers, indicating defective CNTs resulted from low synthesis temperatures.…”

Hierarchical CNTs Grown Multifunctional 3D Woven Composite Beams for Aerospace Applications

“…This ratio indicates that the amount of defective carbons are more than graphitic carbons. The IG/ID around 1 is a typical value for CNTs that were grown onto fibers at around 600 °C growth temperature [28].…”

“…CNTs excluding other compounds that were found in TGA of Neat/GF and Fe +3 /GF. He et al [28] studied CNT loadings varying between 0.2 and 7 wt%, and found that enhancements in both mechanical and electrical properties remained similar for CNT loadings greater than 3 wt%. Therefore, 5 wt% CNT loading obtained in this work can be interpreted as appropriate.…”

“…The elevated temperatures required for CNTs' synthesis in CVD does not influence mechanical properties of thermally resistant alumina fibers, and conformal coating of aligned CNTs can be easily achieved on them; however, the applications of alumina fibers in engineering applications are limited compared to glass and carbon fibers. While complex functional coatings for preventing damage during CNTs growth was used for carbon fibers [27], He et al [28] and Malecki and Zupan [29] achieved CNTs growth onto S2-glass fibers with only catalyst coatings similar to on alumina fibers. He et al reported up to 25%, 36% and 8% enhancements in flexural strength, tensile strength and IFFS, respectively by hierarchical CNTs that incorporated in S2-glass fiber reinforced composites.…”

“…Nevertheless, a severe reduction in tensile strength was observed through the CNTs growth onto the other types of glass fibers [30]. Apart from mechanical properties, the electrical conductivity of glass fiber reinforced composites can be increased several orders of magnitude [31,32] due to the hierarchical conductive CNTs network in entire composite structure.…”