Network structural carbon nanotubes covalently linked graphene composite film for flexible electro-thermal heater with enhanced performance

A high-performance electro-thermal heater needs not only excellent thermal conductivity but high electric conductivity with the aim of a lower operating voltage to generate heat continuously and effectively. The graphene-poly(vinyl alcohol) composite film with carbon nanotubes (CNTs) network structure had been fabricated which has outstanding electrical conductivity and electric heating ability. The influence of CNTs on the electrical conductivity and electro-thermal ability of the composite film materials was investigated by adjusting the ratio of CNTs to Gr. The results show that the Gr sheets and CNTs were successfully connected by chemical bonding using 3-aminopropyltriethoxysilane. The sheet resistivity of Gr/CNTs composite film decreases significantly with the improvement of CNTs content. Besides, the sheet resistivity of Gr/CNTs composite film decreases gradually with the bending times increase. The voltage of 7.0 V can generate a temperature of 143.7 °C, which is not only a human-safe voltage, but also within the support range of most portable power sources. Accordingly, the thin Gr/CNTs composite film supplies a new and simple method preparation of the flexible electro-thermal heater.