Thermal degradation of poly (lactic acid)

• Main Authors: Li Jau-Yan, 李兆彥
• Other Authors: 楊木火
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/04298834317877617273

碩士 === 高苑科技大學 === 高分子環保材料研究所 === 94 === 英文摘要 In this study, the thermal stability for the different molecular weight of poly (lactic acid)s (PLAs) were investigated. The characteristics of PLA were examined by elementary analysis (EA), soild nuclear magnetic resonance (NMR), different scanning calorimeter (DSC), fourier transform infrared spectrophotometer (FTIR), x-ray diffractometer (XRD), thermomechanical analyzer (TMA) and dynamic mechanic analysis (DMA). The thermal degradation behaviors of PLA ( 5,000 and 10,000 g/mole) were carried by dynamic thermogravivetric method and isothermal thermo- gravivetric method under three various condition gas. The experimental results of poly(lactic acid)s are showed that as following : Firstly, physical and morphological properties such as function groups and weight loss were characterized by FTIR, NMR, EA. Secondly, physical and morphological properties such as crystalline melting point, glass transition point, crystallization temperature, softing temperature , degradation behavior and mechanical properties were characterized by DSC, XRD, TMA and DMA. Thirdly, according to Flynn-Wall analytical model, the TGA experimental results showed that the activation energies of dynamic heating of PLA ( 5,000 g/mole) were 91, 158 and 201 kJ/mole and PLA ( 10,000 g/mole) were 141, 224 and 226 kJ/mole under nitrogen, air and oxygen, respectively. Moreover, the thermal degradation behavior activation energies of poly (lactic acid) increase with increase molecular weight and increase with content percentage of oxygen, and it was decreased with increase the weight remaining fraction. Fourthly, according to Flynn-Wall analytical model, the TGA experimental results showed that the activation energies of isothermal of PLA ( 5,000g/mole) were 73, 91, and 108 kJ/mole and PLA ( 10,000g/mole) were 82, 115, and 125 kJ/mole under nitrogen, air and oxygen, respectively. Moreover, the TGA showed that the activation energy increase with molecular weight, and increase with content percentage of oxygen in the weight lossing fraction in the range from 0.05 to 0.75.