A novel gas sensor from polymer-grarfted carbon black: Effects of polymer, crystalline organic compound, and carbon black on electric response to tetrahydrofuran vapor

The responsiveness of electric resistance of three types of composites, polyethylene (PE)/PE-grafted carbon black (CB) (CB-g-PE), N,N'-dicyclohexylcarbodiimide (DCC)/CB-g-PE and PE/DCC/CB-g-PE, to THF vapor was investigated. To modify the CB compatibility in the composite, PE was grafted onto a CB surface. Although responsiveness of composite DCC/CB-g-PE was the most sensitive to THF vapor among the three composites, the composite film is too weak to be of practical use. On the contrary, the responsiveness and the sensitivity of PE/CB-g-PE were too low to be used in many fields. However, through modification by the addition of DCC, responsiveness was greatly improved, and the sensitivity was considerably higher than that of PE/CB-g-PE. The effects of CB-g-PE and DCC content in the composites on the responsiveness to THF vapor was studied in detail. It was found that the responsiveness of electric resistance to THF vapor was caused by the change of the crystalline structure of the composite. A crystalline model was proposed to explain the response of the composite to solvent vapor.