Relationships between organic vapor adsorption behaviors and gas sensitivity of carbon black filled waterborne polyurethane composites

Vapor adsorption behavior and its influence on the gas sensitivity of conductive carbon black filled waterborne polyurethane composites were studied. It was found that the traditional swelling model that was applicable for the reversible variation in the composites electrical resistance induced by the solvent uptake was challenged. That is, the higher adsorption quantity was not bound to result in higher sensitivity to the vapor. On the basis of a detailed study on thermodynamics of adsorption, selective swelling of the segmented microstructure of the composites’ matrix and the preferred distribution of the conductive fillers in the matrix were found to take the responsibility. The solvent–matrix polymer interaction and the chemical characteristics of the solvents determined the relationship between the vapor adsorption behavior and the electrical responsivity of the composites.