Effects of temperature and vapor pressure on the gas sensing behavior of carbon black filled polyurethane composites

The authors of the present work developed conductive composite materials comprised of carbon black and waterbome polyurethane by latex blending. Unlike conventional polymer composites that only respond to certain specific group of solvent vapors, the present composites exhibit electrical resistance responses to a series of vapors of polar and non-polar solvents as a result of the block molecular structure of polyurethane. Under a given vapor pressure, the response rate increases with increasing temperature, but the maximum magnitude of response of the composites decreases because of the effect of vapor desorption. In the case of a constant temperature, the maximum responsivity of the composites increases with a rise in vapor pressure and the relationship follows linear regression within the p/p degrees range of 10(-4) to 2 x 10(-2). Besides, the slopes of the linear dependences vary when the vapor species is changed, suggesting the possibility of quantifying and distinguishing vapors. (c) 2004 Elsevier B.V. All rights reserved.