PNCC Electric Resistance Versus Organic Solvents Vapour Characteristics

There is a necessity for portable and relatively cheap device which could be used for rapid, reversible and in-situ volatile organic compound detection. We offer a polyisoprene-nanostructured carbon composite (PNCC) us a promising material for organic solvents vapour detection and identification in the environment. Previously obtained experimental results verify that PNCC can distinguish 10 different organic solvents saturated vapour. When PNCC is exposed to organic solvents vapour, molecules of vapour adsorbe on the surface of the composite and diffuse into matrix material. At the same time decreases the tunnelling currents between carbon aggregates in thin layers of matrix and the electrical resistance of the composite increases. In the presence of organic solvents vapour electric resistance changes remarkably in short time (30s) and the effect is reversible. The largest electric resistance change velocity (vR) is observed for tetrahydrofuran (0,19404 KΩ/min), benzene (0,13082 KΩ/min) and ethylacetate (0,10694 KΩ/min) vapour. But nearly no vR change is observed, when PNCC is exposed to propanol vapour (0,004028 KΩ/min). We relate this variant electric resistance response of PNCC to organic solvents vapour variant compatibility with the composites matrix material (polyisoprene) and variant organic solvents vapour molecule dimensions. To evaluate vapour compatibility with the composite matrix material we compared dielectric permeability values of vapour (εv) and polyisoprene (εp). We observed that larger vR change is reached when εv value is close to εp (2,68) value. PNCC organic solvents vapour sensitivity is selective. The composite does not respond or respond weakly to polar organic solvents vapour presence. Also in the electric resistance response evaluation of PNCC molecule dimensions of organic solvents vapour should be taken into account. As smaller the diameter of vapour and better compatibility with matrix material us greater electric resistance response of PNCC is observed