OBTENÇÃO DE NANOCOMPÓSITOS CONDUTORES BASEADO EM POLIURETANO DE ÓLEO DE MAMONA COM NEGRO DE FUMO E NANOTUBOS DE CARBONO VISANDO SUA APLICAÇÃO COMO SENSOT PIEZORESITIVO

Abstract

Conductive polymeric composites, also called extrinsic conductive polymers, have been extensively researched by the scientific community due to their higher potential for application in the most diverse industrial sectors. These materials combine the characteristics of a polymer (lightness, flexibility, easy processing) with those of conductive charges (high conductivity) to form a conductive nanocomposite. Polyurethane derived from castor oil (PUR) is a polymer obtained by mixing polyol and prepolymer, which has great potential to be used as a polymer matrix in composites. PUR has properties equivalent to those of conventional polyurethanes (PU) and has the advantage of being a biodegradable polymer from a renewable source. Regarding conductive charges, carbon black (NF) and carbon nanotubes (NTCs) are one of the most used materials for this purpose. In this context, the present work aims to carry out the synthesis processes and understand the electrical characterization of polyurethane composites derived from castor oil with NF and NTCs (PUR-NF/NTCs) obtained in the form of films by the "casting" method, keeping the polyol/prepolymer ratio fixed and varying the mass fractions of NF and NTCs. The study of conductivity in direct current (dc) and alternating current (ac) were obtained by the Two-Prong Method (voltage x current) - (MDP) and by the technique of Electrical Impedance Spectroscopy (EIE), and the morphological analysis was performed in Scanning Electron Microscope (SEM). As for the electrical analysis, the results showed that the PUR-NTCs/NF samples have a lower percolation threshold around 1.5%, whereas the PUR-NF/NTCs samples have a percolation threshold of 3.5%. This result is due to the better distribution of the NF particles, in relation to the CNTs, through the polymeric matrix, and the better dispersion of NF could be confirmed by the images obtained in SEM. The results of piezoresistive tests showed sensitivity. So because it has excellent properties, this material can be applied as a sensor.