POLYISOPRENE – NANOSTRUCTURED CARBON COMPOSITE (PNCC) MATERIAL FOR VOLATILE ORGANIC COMPOUND DETECTION Gita Sakale, Maris Knite, Valdis Teteris Institute of Technical Physics, Riga Technical University, Azenes iela 14/24, Riga, Latvia Velta Tupureina Institute of Polymer Materials, Riga Technical University, Riga, Latvia Keywords: Polymer-high structured carbon black composite, Volatile organic compound sensors. Abstract: Our scientific group has chosen the elaboration of conductive composite material, which could be useful for volatile organic compound detection, as one of research areas. It was found out that the most sensitive composite material consists of polyisoprene and 10 mass parts of nanostructured carbon black. The electric resistance changes of the composite in presence of 10 different saturated organic solvents vapour were measured. Results obtained form our mass-sorption experiments indicated that electrical resistance of the composite increases because of volatile organic compound (VOC) molecule absorption in the composite matrix material. We also evaluated VOC compatibility with PNCC matrix material and estimated how the PNCC resistance change velocity ( R v ) versus organic solvent vapour molecule diameter varies. 1 INTRODUCTION Available statistical data evidence about people exposed to organic solvent daily at their workplaces, but there are no monitoring devices used to control VOC concentration in the room. There is also a necessity to protect environment and equipment from exposure to VOC. Above mentioned denotes that there is an urgent need for VOC sensor materials. Devices (sorbent polymer films, metal oxide semiconductors, quartz microbalance (quartz resonator), laser gas sensors ect.) in the market can not still be compared with mammal’s olfactory system. Scientists are trying to design a prototype of sensor which in sensing capability of different gases could be close to mammals olfactory system and even could be improved for practical applications. We think that the desirable result of VOC detection can be achieved by using polymer – carbon black composites as gas sensor materials because polymer matrix can be selected for direct volatile compound detection and identifying. In our opinion a candidate sensor material for gas sensing should fulfil the following criteria: not expensive constituent materials; simple production; fast and reversible response; in-situ control of VOC; small dimensions of sensing element and ability to function for a long period of time. The mechanism how polymer – carbon black composite detects VOC is as fallows: i) the sample of the composite material is exposed to VOC, molecules of VOC adsorbe on the surface of composite and diffuse into the matrix material; ii) intermolecular chains in the polymer matrix weaken and form intermolecular chains between VOC molecules and macromolecules of matrix material; iii) the matrix material swells; iv) electroconducting pathways break down because distance between carbon black aggregates increases; v) at the same time tunnelling currents between carbon aggregates in thin layers of matrix decreases and the electrical resistance of the composite increases. 2 EXPERIMENTAL Polyisoprene – nanostructured carbon composite material was made by rolling highly structured nano- size carbon black PRINTEX XE2 (specific surface 117 Sakale G., Knite M., Teteris V. and Tupureina V. (2009). POLYISOPRENE – NANOSTRUCTURED CARBON COMPOSITE (PNCC) MATERIAL FOR VOLATILE ORGANIC COMPOUND DETECTION. In Proceedings of the International Conference on Biomedical Electronics and Devices, pages 117-122 DOI: 10.5220/0001557301170122 Copyright c  SciTePress