Low carbon black filled polyurethane composite as candidate for wide spectrum gas-sensing element

摘要

To reduce the amount of carbon black and to broaden the applicability of conductive polymer composites serving as gas sensors, polyurethane-based composite was prepared by latex blending. The composite has very low electrical threshold and hence provides improved processability. In the environment of organic solvent vapors, the composite with 3.5 wt. percent of carbon black exhibits significant increase of its electrical resistance regardless of the solvents' polarities and the maximum variation in resistance decreases linearly with decreasing vapor concentration. Besides, the slopes of the linear dependences change with the solvent species, which might-allow quantifying vapor concentration and species. The measurable vapor concentrations of the composite are lower than or equal to the Chinese standard of exposure limits. Besides, the composite also shows high reproducibility as evidenced by over 5000 times of repeated sensing tests. It is believed that the composite can be used in gas sensor arrays with much smaller sizes and wide sensitivity.