Polymer composites sensing properties

FEL 11] Feller J.F., Castro M., Kumar B., Tolymer CNT conductive nanocomposite for sensing . Polymer Carbon Nanotube Composites Preparation, Properties and Applications, McNally T. (ed.). Chapter 25, Woodhead Pubhshing, Cambridge, p. 848,2011. 

The main purpose of incorporating second phase to polymer matrix is to enhance properties of materials and use them for various applications. The hierarchical structures of polymer composites were also developed for better performances of electronic devices based on them. Here, the mechanical, electrical, electrochemical and electroluminescent, as well as the sensing properties of polymer composites were summarized. 

When compression is applied on a polymer composite filled with conductive particles, the interparticle distance is reduced. This translates into an increase in conductivity as more electrons can flow through filler particles physically in contact and tunnel through the barriers, which under compression become thinner , and the probability that a decaying electron wave crosses over to the other end is higher. This property can be used for compression sensing. 

Radeva E, Georgiev V, Spassov L, Koprinarov N, St K (1997) Humidity adsorptive properties of thin fullerene layers studied by means of quartz micro-balance. Sens Actuators B 42 11-13 Ramos MV, Al-Jumady A, Puli VS (2005) Conductive polymer-composite sensor for gas detection, In Proceedings of 1st international conference on sensing technology, Palmerston North, New Zealand, 21-23 November 2005, p 213-216... 

It was found that transition to nanocomposites could also improve mechanical properties and promote stabilization of the basic material s parameters (Konig 1987). For example, it was established that in CNTs-polymer composites, the presence of carbon nanotubes inside the polymeric matrix can provide a mechanical support to the polymeric chain s conformational rearrangement. CNTs are hollow nanopipes, and therefore the incorporation of CNTs in a metal oxide matrix can provide better gas permeability for sensing materials and thus enhance gas diffusion into the bulk film. Thus, combination of CNTs with metal oxide (see Fig. 12.1) can lead to development of gas sensors with improved rate of response. 

Buchler MG, Ryan MA (1997) Temperature and humidity dependence of a polymer-based gas sensor. Proc SPIE 3082 40-48. http //enose.jpl.nasa.gov/publications/sensors/97-0482.pdf Cabala R, Meister V, Potje-Kamloth K (1997) Effect of composite doping on sensing properties of polypyrrole. J Chem Soc Faraday Trans 93 131-137... 

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