Effect of multi-walled carbon nanotube reinforcement on the physical properties of poly(thiourea-azo-ether)-based nanocomposites

Abstract

In the current effort, heteroaromatic azo-polymer, poly(thiourea-azo-ether) was prepared using 4,4′-oxydiphenyl bis(thiourea) and diazonium salt solution of 2,6-diaminopyridine. Poly(thiourea-azo-ether) was then exploited as a matrix to synthesize new hybrid materials. Varying carbon nanotube content was melt blended with the azo-matrix. The effect of filler loading on processing and other thermo-physical properties of poly(thiourea-azo-ether)/multi-walled carbon nanotube was investigated. Homogeneous dispersion of multi-walled carbon nanotube in a polymer matrix plays a crucial role in the preparation of polymer composites based on interfacial interaction between multi-walled carbon nanotube and the polymer matrix. Field emission scanning electron microscopy micrographs revealed fine dispersal of filler and adhesion of matrix on the surface of nanotube. Accordingly, filler content from 1 to 5 wt.% increased the electrical conductivity from 2.3 to 4.8 S cm⁻¹. Ultimate tensile strength of functional hybrids 37.39–41.23 MPa was improved relative to non-functional multi-walled carbon nanotube in matrix. Furthermore, the tensile modulus considerably increased from 9.9 to 13.3 GPa. A connection between filler loading and thermal stability of the materials was also observed. Ten percent gravimetric loss was increased from 592 to 599℃, while glass transition was enhanced from 201 to 221℃. The addition of small amount of functional multi-walled carbon nanotube strongly improved the electrical, thermal and mechanical properties of nanocomposites. The melt processing technology was so found outstanding for the improvement of the properties of multi-walled carbon nanotube-reinforced polymer nanocomposites.