Preparation And Properties Of Polymer Electrothermal Films Based On Superconductive Carbon Black

As an energy-saving and environmental-friendly heating method,the electrothermal film plays an important role in many fields such as underfloor heating,snow melting and deicing and medical care.However,the conventional inorganic electrothermal film has disadvantages such as single-function nature,heating unsteadily and short life.Besides,some fields have special needs for electrothermal film.Therefore,it is of great significance to study and develop functional polymer electrothermal film with excellent comprehensive performance for the development of electrothermal film market.In this paper,the superconductive carbon black(SCB)was used as conductive filler,and two kinds of polymer composite films were prepared by solution blending method using the poly(vinylidene fluoride)(PVDF)and polylactic acid(PLA)resin as organic binder,respectively.Furthermore,the influences of SCB on conductivity,mechanical performance and electrothermal property of composite films were studied.The results show that the addition of SCB can observably enhance the electrothermal properties of the composite films.For PVDF/SCB composite films,the conductivity of film reached to 10~-33 S/cm when 3 wt%SCB was added.And the composite film was transformed from an insulator to conductor.As the content of SCB was 7 wt%and 10 wt%,the composite films showed excellent electrothermal performance.After being energized for 6 min at 60 V voltage,the surface temperature of the film reached 61 ~oC and 79 ~oC,respectively.The average temperature rise and equilibrium temperature of the composite film increase linearly with the increase of power density in the range of 250-3000 W/m~2.The addition of SCB did little damage to the mechanical properties of PVDF.The composite films show the high flexibility with a 372.8%elongation at break even if the addition amount of SCB was 10 wt%.For PLA/SCB composite films,the conductive percolation threshold was 2 wt%.When the SCB content was 5 wt%and 7wt%,the equilibrium temperature of the two composite films at 60 V voltage was 56 ~oC and 69 ~oC and the average heating rate was 4.33 ~oC/min and 5.48 ~oC/min,respectively.Superconductive carbon black-copper nanowires hybridized(SCB@CuNWs)were prepared by liquid phase reduction method.And then PLA/SCB@CuNWs composite films were prepared by solution blending.The results show that the conductivity suddenly changed and the increase was up to 11 orders of magnitude when the amount of conductive filler was 1wt%.Meanwhile,the tensile strength and elongation at break of the composite film reached56.6 MPa and 40.8%,respectively,which was 9.7%and 42.6%higher than that of pure PLA.When the content of SCB@CuNWs was 3 wt%,5wt%and 7 wt%,the heating temperature of the composite film surface at 36 V safe voltage increased from room temperature to 32 ~oC,36~oC and 42 ~oC respectively.Besides,the higher the voltage of the composite films was applied,the higher the equilibrium temperature reached.