Elastomeric blends of poly(styrene-butadiene-styrene) and conductive heteroaromatic poly(thiourea-azo-ether)

Abstract

The present work involves the preparation of a new heteroaromatic azo polymer, poly(thiourea-azo-ether; PTAE) using 4,4′-oxydiphenyl bis(thiourea) and diazonium salt solution of 2,6-diaminopyridine. The polymer was easily processable using polar solvents and had high molar mass of 33 × 103 g mol−1. Various concentrations of azo filler and poly(styrene-butadiene-styrene; SBS) blends were then blended in solution phase. The effect of PTAE on processing, conductivity, morphology and thermophysical properties of elastomeric blends was investigated. Field-emission scanning electron microscopic micrographs of SBS/PTAE blends revealed fine dispersal of filler, good adhesion with the matrix and the development of conducting pathways. Accordingly, filler content from 10 to 60 wt% increased the conductivity from 0.77 × 10−1 to 1.43 S cm−1. Ultimate tensile strength of SBS/PTAE (26.94–28.12 MPa) was improved relative to pure SBS. A relationship between PTAE loading and thermal stability of the materials was also observed. The temperature at 10% gravimetric loss was increased from 461 to 499°C, while the glass transition temperature was enhanced from 135 to 147°C. Thermal and conducting data showed better results relative to pure elastomer but lower than the conducting filler. Fine balance of properties renders new materials better than the existing elastomeric blends used in a number of applications.