Synthsis And Characterization Of Thermoplastic Polyurethane Functional Composites

Thermoplastic polyurethane (TPU) has wide applications owing to its excellent performances such as high hardness and resilience, good oil resistance, ozone resistance and outstanding low temperature performance. However, TPU is easy to be softened and decomposed at high temperatures, which leads to the sharp decline in mechanical properties. In general, its long-term using temperature can not exceed 80℃, and short-term using temperature can not exceed 120℃, which greatly limits its scope of application. How to improve the heat-resistant property of TPU, meanwhile ensure the comprehensive performance remain at its original level, is the key point in the research of TPU. As we all know, inorganic materials have many characteristics, for example, high melting point and hardness, good wear resistance, corrosion resistance and oxidation resistance, etc. In addition, the inorganic nanoparticles with unique optical, electrical, magnetic and chemical properties, which opened up a new way for the preparation of high-performance and multi-functional composites. In recent years, the modification of TPU by using inorganic particles as reinforcement is becoming a primary method. In this paper, three different kinds of inorganic particles were selected for preparing three kinds of TPU functional composites by solution blending. The heat resistances, mechanical, flame retardant and magnetic properties of TPU were greatly improved.In this thesis, porous diatomite was used as filler of TPU for the first time. The TPU molecular chains are forced around the pores of diatomite to form a mechanical interlocking structure. which can improve bonding between filler particles and the TPU. Fourier transform infrared spectroscopy (FTIR), thermogravimetric analyzer (TGA), scanning electron microscopy (SEM), electronic universal testing machine, dynamic mechanical analyzer (DMA) were used to characterize these composites. Results indicated that the mechanical properties and heat resistance of TPU/diatomite composites were significantly improved. The tensile strength of the composites was increased by 62.2%.The surface of magnesium hydroxide (MH) particles were modified with 3-methacryloxypropyltrimethoxysilane (y-MPS). And the TPU/MH composites were synthesized by solution blending. FTIR, field emissiom scanning electron microscopy (FE-SEM), TGA, electronic universal testing machine. DMA, oxygen index test instrument were used to characterize these composites. Results indicated that the mechanical properties and heat resistance of TPU/MH composites were significantly improved. The thermal decomposition temperature of the composites was increased 59℃for 30% mass loss. And the Limited Oxygen Index (LOI) values of TPU/MH composites were improved from 20.5% to 22.7%.A magnetic multi-walled carbon nanotubes-based (MWCNTs-based) composite, MWCNTs/Co1-xZnxFe2O4, was synthesized via a facile solvothermal approach. And the TPU/Co0.5Zn0.5Fe2O4 nanocomposites were synthesized by solution blending. X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), FE-SEM, TGA, electronic universal testing machine, DMA were used to characterize these composites. The results showed that the saturation magnetization of the MWCNTs/Co1-xZnxFe2O4 magnetic nanocomposites increased with x when the Zn2+ content was less than 0.5, but decreased rapidly when the Zn2+ content was more than 0.5. The saturation magnetization as a function of Zn2+ substitution reached a maximum value of 57.5 emu·g-1 for x=0.5. The mechanical property, heat resistance and magnetic property of TPU/MWCNTs/Co0.5Zn0.5Fe2O4 nanocomposites were significantly improved. And the saturation magnetizations of TPU/MWCNTs/Co0.5Zn0.5Fe2O4 nanocomposites was increased by 30.30 emu·g-1.