Nanocomposites Based on Thermoplastic Polyurethane, Millable Polyurethane and Organoclay: Effect of Matrix Composition and Dynamic Vulcanization

Dynamically vulcanized thermoplastic polyurethane (TPU)/millable polyurethane (MPU) blend nanocomposites, simple TPU/MPU blend nanocomposite, and TPU nanocomposite with 3 parts per hundred (phr) of organoclay were melt compounded in an internal mixer. Interfacial interactions between the organoclay and polyurethanes were examined by Fourier transform infrared spectroscopy, X-ray diffraction, and transmission electron microscope analysis, which revealed that the dispersion of organoclays significantly improved with increasing TPU content in the TPU/MPU blends and dynamic vulcanization process. Tensile test and dynamic mechanical analysis showed that the mechanical properties are improved with the TPU content in the TPU/MPU blends and dynamic vulcanization process. Both hardness and tension set of the samples decreased with increasing MPU content in the TPU/MPU blends. Thermal stability determined by thermo-gravimetric analysis revealed that it increased with increase in TPU concentration in the samples. Differential scanning calorimetry study showed that the glass transition temperature (T-g), melting temperature (T-m), and melt crystallization temperature (T-c) of the samples were significantly affected by the blend composition and dynamic vulcanization. Dynamic melt rheology of the nanocomposite samples in the molten state revealed a pseudo solid-like behavior as well as an enhanced shear thinning behavior, and the variation of the rheological properties are well correlated with blend compositions and morphology of the nanocomposites. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4014-4023, 2013