Thermal Characteristics of TIO2 Nanocomposite in a Polyurethane Matrix Made with Castor Oil

Abstract

Nanocomposites are multiphase structures with at least one phase dimension of nanometric order size. Polymer-based materials mixed with low proportions of titanium dioxide nanoparticles (NPs-TiO₂) present a versatile alternative in different industrial applications, considering the optimization of mechanical and thermal properties with respect to pure polymers and conventional materials. In this work, the synthesis and measurement of thermal characteristics of a nanocomposite formed by NPs-TiO₂, 5 nm particle size Anatase phase, in a polyurethane matrix, made with castor oil is reported. The polymeric matrix was obtained through the reaction between the self-condensation of castor oil and diphenylmethane diisocyanate (MDI), while in the synthesis of NPs-TiO₂ the sol-gel technique was used, using as precursor titanium (IV)-bis(acetylacetonate) diisopropoxide. The specific heat (C_p) of the samples was measured by means of the thermal relaxation method and the thermal diffusivity was determined with the photoacoustic technique (α). C_p of the nanocomposite increased by 12.98 % due to addition of the NPs, while α decreased by 98.63 %, compared to the corresponding values of the polyurethane matrix. With a concentration of 3 wt % of NPs-TiO₂ in the matrix, these thermal parameters were found to be below the average values of conventional plastics.