Processing of of nanocomposites using supercritical fluid assisted extrusion for stress/strain sensing applications

The problem of dispersion of nano-additives in thermoplastic elastomers using continuous processing techniques still prevails in scientific and engineering applications. To address this, supercritical fluid (SCF) assisted extrusion was utilised to develop elastic, isotropic and electrically superior materials, which contain elastomeric microphases of Poly(styrene-ethylene-butylene-styrene [SEBS] with homogeneously dispersed conductive nano additives of carbon black [CB]. SEBS-SCF/CB 5 wt% extrudates showed 46% and 14% higher storage modulus compared to their counterparts in transverse and longitudinal direction respectively. Similarly, piezo-resistive properties of SEBS-SCF/CB composites were found to have a superior strain gauge factor with linear decrease in conductivity with increasing strain, compared to nonlinear increase/decrease in piezoresistive behaviour of SEBS/CB composites. Piezo-resistivity of SEBS-SCF/CB 5 wt% nanocomposites were found to be highly sensitive in both bending (3.6% change in resistance per degree for 1.7 cm thick sample) and tensile strain conditions (gauge factor ca. 9) for smart applications.