Effects of heat-treatment on the gas response of PVDF/CB conductive composite sensing films

A novel conductive composite sensitive film was prepared by filling carbon blacks (PVDF/CB) into poly(vinylidene fluoride) matrix (PVDF). The percolation behavior and positive vapor coefficient peculiarity (PVC) were investigated, and the effect of different ways of thermal treatments on the PVC peculiarity was also explored. The relation between the crystalline behavior as well as the surface configuration and the gas sensing peculiarity was discussed by means of wide angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). The results showed that the initial resistance values of the thin films undergoing different heat-treatments all declined-compared with those of the untreated films. The responsive patterns and responsibility of the composite materials with thermal treatment to acetone and tetrahydrofuran (THF) vapors obviously improved. Especially, the resistance reproducibility of the thin films annealed at 80 ℃ for 2 h to acetone and THF vapors was optimal.