| Summary: | 碩士 === 淡江大學 === 化學工程與材料工程學系碩士班 === 96 === In this research, two different (diol and diamine) chain extenders containing a thiol group were used to prepare polyurethanes (PUa and PUo) respectively. FT-IR and NMR results indicate the correct formation of the polyurethanes. Then, the two prepared polyurethanes containing thiol groups on the chain side acted as protectors to synthesize gold nanoparticles (GNPs) by the chemical reduced method, and polyurethane-nanogold nanocomposites were formed. The sizes of the prepared GNPs and the effects of the GNPs contents on the microstructure and properties of the nanocomposite were investigated by scanning electron microscopy (SEM), transmittance electron microscopy (TEM), UV-Vis spectrometer (UV-Vis), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) , and universal testing machine. UV-Vis, SEM, and TEM results show that GNPs are dispersed well in the prepared nanocomposites and no large-scale aggregation occurs. Thus the prepared polyurethanes containing thiol groups on the chain side can avoid the aggregation of GNPs and improve the amount of GNPs in the PU matrix. The investigation on thermal properties of nanocomposites by TGA , DSC and DMA , which results and shows degradation temperature reduced 10 oC and glassy transition temperature reduced 3 oC. The results of stress-strain behavior shows a special phenomenon , that is we could use less force to achieve the same elongation. It means that nanogold played a plastic agent more than crosslink agent.
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