| Summary: | 碩士 === 國立臺灣科技大學 === 材料科學與工程系 === 103 === Adhesives were prepared by using various mole ratios of bis-phenol A diglycidyl methacrylate（BisGMA）(50~80 mol%) and triethylene glycol dimethacrylate (TEGDMA) (20~50 mol%) in feed, with camphorquinone (CQ) and diphenylphosphine oxide as the photoinitiators. We use the different photocuring times (2~6 mins) and different light intensities (600~1800 mW/cm2) of visible light. We examine the effects of BisGMA/TEGDMA mole ratios in feed, photocuring times and light intensities on conversion of reaction, and how crosslink density and conversion of reaction affect the interactions between water and polymers in swollen resins and dynamic mechanical properties of dry resins.
According to FTIR analysis, as the contents of BisGMA increase, the photocuring times increase or the light intensity increases, the conversions of double bonds increase. There is a power raw relationship between the conversion and light intensity with an exponent equal to 0.226~0.371. The order of propagation reaction (n) and reaction rate constant (k) are calculated by the conversions of double bonds versus photocuring times. As the contents of BisGMA increase or the light intensity increases, both of the n values and k values decrease. Compressive modulus and crosslinking density increase with increasing the contents of BisGMA in feed. Both of the density of physical entanglement（Ns）and the density of chemical crosslinking in network（Nc） increase with increasing the contents of BisGMA in feed, showing that adding BisGMA is favorable for physical and chemical crosslinking. And increasing the photocuring times or the light intensities, leads to similar results to the above. In addition, the interaction parameters of water and polymers in adhesives (χ) were calculated by crosslinking densities and equilibrium water contents. As the contents of BisGMA increase, the photocuring times increase or the light intensity increases, the χ values increase and the equilibrium water contents decrease. Curing volume shrinkages decrease with increasing the contents of BisGMA in feed or increasing the light intensity because of BisGMA with benzene structure offering the less shrinkage than TEGDMA. But increasing the photocuring times, the curing volume shrinkages increase. According to DMA analysis, as the contents of BisGMA increase, the photocuring times increase or the light intensity increases, the storage modulus and the glass transition temperature (Tg) will increase. The glass transition temperature is increased by increasing crosslink density, there is a linear relationship between them. And there is a power raw relationship between the storage modulus and crosslink density with an exponent equal to 1.918.
Experimental results show that we vary BisGMA/TEGDMA ratios in feed, photocuring times or light intensities, that will influence the conversions of double bonds, network structure of polymer and crosslink density, thereby affecting the interactions between water and polymers in swollen resins, as well as affecting dynamic mechanical properties of dry resins.
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