| Summary: | 碩士 === 台北醫學院 === 口腔復健醫學研究所 === 89 === The purpose of this study is to improve the properties of bioresorbable materials for particular applications in dental and orthopedic surgery. Blends of biodegradable poly-L-lactic acid (PLLA), poly- DL-lactic acid (PDLLA) or polycaprolactone (PCL) , and a third component, the surfactant PEO-PPO, were prepared by blending these three polymers at various ratios using dichloromethane as a solvent. The weight percentages of PLLA/PDLLA (or PCL) blends were 100/0, 80/20, 60/40, 50/50, 40/60, 20/80 and 0/100, respectively. Physical and morphological properties such as crystalline melting point, glass transition point, phase behaviors, degradation behavior and mechanical properties were characterized by thermogravimetric analysis, differential scanning calorimetry, infrared spectroscopy, gel permeation chromatography, scanning electron microscopy and dynamic mechanical analysis. DSC data indicate that PLLA/PDLLA blends without PEOPPO have two Tgs. With the addition of PEOPPO, there is a linear shifting of Tg as a function of composition showing a lesser percentage of PLLA, and a lower glass transition temperature indicating better miscibility has been achieved. DMA data show the best composition of PLLA/PDLLA blends without PEOPPO is 40/60, and the best concentration of PEOPPO is 2%. The 50/50 PLLA/PDLLA/2%PEOPPO blend has better mechanical properties. Elongation of PLLA increases while adding PCL, but the strength decreases at the same time. SEM observation shows that harder and tougher materials have rougher fracture surface morphology.
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