N991/MWCNTs/PEO composite films with nano SiO 2 particles as filler for advanced flexible electric heating elements

Abstract Carbon/polymer based flexible electrothermal films due to the excellent formability, flexibility, light weight and cost-effectiveness are recognized as a promising alternative material compared to traditional metal based materials. In this work, a series of flexible electrothermal films were synthesized by incorporating pyrolysis N991 and multi-walled carbon nanotubes (MWCNTs) in polyethylene oxide (PEO) matrix with adding non-conductive SiO 2 filler. The influences of SiO 2 on morphology, microstructure and electrothermal performance of electrothermal films were systematically investigated. SiO 2 filler guarantees the homogeneous dispersion of N991 and MWCNTs in PEO polymer matrix, which could prevent the unceasing migration of N991 and MWCNTs during the repeating heating-cooling cycles. The result shows that adding 5 wt.% SiO 2 can achieve a stable electrical resistivity and excellent electrothermal reproducibility. Bending tests were employed to evaluate its superior mechanical flexibility. A new application was further developed to fabricate a flexible electrothermal film with a reversible thermochromic temperature-indicating function.