Molecular design and preparation of an integrated CNT@EVA/PVDF composite film heater for effective deicing applications

摘要

Composite film heater is becoming the focus of research in the deicing field, owing to its advantages of high electro-thermal efficiency and lightweight. In this work, a new composite film heater with ultralow conductive filler was designed and prepared by mixing insoluble ethyl vinyl acetate (EVA) and soluble polyvinylidene fluoride (PVDF) in dimethylformamide (DMF). It is common sense that many insoluble EVA fillers degrade mechanical properties due to the macro-interface defect. The molecular dynamic simulation indicated that interfacial blending regions were formed more easily between molten EVA and soluble PVDF on account of the similar solubility parameter and stronger adsorption energy between Vinyl acetate segmer and PVDF segmer. The semi-compatible system was favorable to eliminate the macro-interface defect between EVA and PVDF partially. The film heater showed better tensile strength, flexibility, and bending durability after heat treatment of 80 degrees C. Moreover, the film heater had an outstanding heating effect, fast electro-thermal response time, low-energy consumption, and excellent thermal cycling stability. It achieved the steady-state temperature of 117.4 degrees C and the heating rate of 1.348 degrees C/s when the ratio of PVDF to EVA was 1:1 and the amount of CNT was only 10 at 28 V. The optimal ratio of CNT and EVA could construct a double reticular structure, consists macroscopic and microscopic conductive network at the same time, thereby reducing the content of conductive filler significantly. Furthermore, the deicing experiment manifested that the icicle fell after 29 s at 28 V, much shorter than without loading current. The integrated CNT@EVA/PVDF composite film heater contributes to a better understanding of the low percolation effect and the distribution mechanism between molten EVA and soluble PVDF, which could conduce to the development of novel electro-thermal deicing film in future.