A small amount of amino functionalized multi-walled carbon nanotubes (a-MWCNTs) (10 wt%) are added not only to increase the mechanical strength of the plane heater, but also to improve the heat conduction in the nanocomposite. Therefore, while graphite nanocomposite film mostly peeled off after an adhesion test, a-MWCNT- graphite nanocomposite film adhered on the PET substrate without noticeable change.