| Summary: | 碩士 === 中國文化大學 === 應用化學研究所 === 87 === The purpose of this study is to synthesize gas-permeable water-based polyurethanes (called GP-PU) by means of acetone process and to explore their physical and gas-permeable properties.
The formation of GP-PU, due to the decrease in the
-NCO absorbance peak, the disappearance of the -OH absorbance peak, the appearance of HN-C=O, (C2H5)3NH and -NH peaks as well as the DMDCS peaks, is demonstrated by IR spectra. The experimental results show that the viscosity, surface tension and diffusion coefficient of the GP-PU molecule decrease with increasing the concentration of the DMDCS present in the system, but the partical size of the GP-PU increases with increasing the concentration of DMDCS in the system. As the concentration of the DMDCS is fixed, the viscosity and partical size of the GP-PU may increase with raising the ratio of NCO to OH. However, the surface tension of the solution is not affected by the variation of the ratio of NCO to OH.
Since the amount of DMDCS on the main chain of polyurthane moleculeincreases and may be affected by
the presence of other major compontents ,therefore ,the rate of the hardness of the water-based polyurethance can not be speeded up. The tensile strength, the elongation and the 100% modulus of GP-PU may decrease with increasing the concentration of DMDCS. As the concentration of DMDCS is fixed, the tensile strength, the elongation and 100% modulus of the GP-PU film may become greater as long as the ratio of NCO to OH is raised.
The thin film of water-based polyurethanes containing DMDCS id better than that of water-based polyurethanes without DMDCS for permeability of this film to oxygen. However, the permeability of this film to the oxygen is increased as the amount of DMDCS present in the water-based polyurethane increases.
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