Synthesis of CNT-polyurethane nanocomposites using ester-based polyols with different molecular structure: Mechanical, thermal, and electrical properties

Polyurethanes (PUs) were prepared by in situ polymerization of three diisocyanate with three synthesized low cost ester-based polyols. The effect of diisocyanate type, diol structure, and molar ratio of diisocyanate to polyol on the mechanical properties was examined and the optimum chemical structure was introduced regarding the superior mechanical properties. Also, in presence of well dispersed hydroxylated multiwalled carbon nanotubes (CNT), PU/CNT nanocomposites were synthesized and fully characterized. The results showed that PU synthesized based on 1,4-butane diol (BDO) has the best mechanical properties and thermal stability. Also, the PU samples synthesized from 1,6-hexamethylene diisocyanate (HDI) were more profitable than aromatic diisocyanate structures due to higher crystallinity and microstructure packing. The nanocomposite sample containing 1.5% CNT was the optimum composition for the maximum tensile strength and electrical conductivity. This result was related to the uniform dispersion and bonding of CNTs to PU chains at this composition, while aggregates were formed at higher concentration of CNTs which increased the defects and reduced the uniformity of the structure. (C) 2016 Wiley Periodicals, Inc.