| Summary: | 碩士 === 國立勤益科技大學 === 化工與材料工程系 === 102 === Polyurethane (PU) is an important material because of its advantages such as physical and chemical properties, good wear resistance and excellent flexibility. It is widely used in synthetic leather, paints, adhesives, foams, films and elastics. The thermal stability of pure PU generally is low at high temperature, and its pyrolysis temperature is slightly higher than the processing temperature. This study focuses on the promotion of thermal stability and mechanical properties of the PU. Graphene is recognized as another concern of carbon nanomaterials expect for carbon nanotubes, due to it is light, electric, magnetic, mechanical and other unique characteristics.Graphene has a lot of development and application prospect in the field of optoelectronic materials, nanodevices and composite materials.
The graphene oxide (GO) was prepared by modified Hummer method.The functionalized graphene oxide (GO-IMD) was synthesized from GO and 1-(3-aminopropyl) imidazole. The PU/GO, PU/GO-IMD and PU/GNS nanocomposite materials were prepared by adding 0.2, 0.5, 1.0, 1.5 and 3.0 wt% of graphene oxide, functionalized graphene oxide and graphene into the pure PU. 0.2, 0.5, 1.0, 1.5 and 3.0wt% in the blend mode, respectively. We studied the effects of GO, GO-IMD, GNS added on the thermal properties and mechanical properties of pure PU.
Fourier transform infrared spectroscopy (FTIR) was used to identify the binding situation of nanocomposite materials. Solid-state nuclear magnetic resonance (NMR) was used to identify the presence of imidazole graft 1-(3-aminopropyl) or not. Identify peaks and functional groups were detected by X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy (Ramam) to determine the degree of graphite. The thermal properties of the glass transition temperature (Tg) and thermal decomposition temperature (Td) of the prepared nanocomposites were obtained by dynamic mechanical analyzer (DMA) and thermogravimetric analyzer (TGA), respectively. The tensile properties and the surface morphology were observed by using a tensile testing machine and Scanning electron microscopy (SEM).
From FTIR spetra show 1-(3-aminopropyl) imidazole binding with GO via covalent, the peak of GO-IMD appeared at 2925-2855cm-1 indicates that the connection of the imidazole ring CH and NH2.Graphene oxide contain signal at 1440cm-1 associated with the CO-NH group, indicating that the treatment of GO with IMD results in chemical reaction. From the Raman data, we can see that the G band peaks of GO-IMD, which means the degree of symmetry and orderly changed shifted. The Td of the nanocomposite materials increased with increasing the content of GO, GO-IMD and GNS. The Td of pure PU is 266 °C. The composites with 0.5wt% of GO, GO-IMD and GNS, the values of Td were 283 °C, 289 °C and 294 °C respectively. The increased of Td were 17 °C, 23 °C and 28 °C, respectively. Tensile test results indicated that the tensile strength of the nanocomposite were always higher than that of pure PU.The composite with 0.5wt% GO exhibited.The highest tensile strength of 16.3MPa and an increased of 676% when compared to pure PU(2.1MPa).The Young's modulus of nanocomposites werw always higher than that of pure PU(2.4MPa).The composite with 1.5wt% GO exhibited the highest modulus of 11.6MPa, an increase of 383%.From there results,the thermal properties and mechanical properties of PU were improved by adding GO, GO-IMD and GNS.
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