Mano J F, Koniarova D, Reis R L
Department of Polymer Engineering, University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal.
J Mater Sci Mater Med. 2003 Feb;14(2):127-35. doi: 10.1023/a:1022015712170.
Previous studies shown that thermoplastic blends of corn starch with some biodegradable synthetic polymers (poly(epsilon-caprolactone), cellulose acetate, poly(lactic acid) and ethylene-vinyl alcohol copolymer) have good potential to be used in a series of biomedical applications. In this work the thermal behavior of these structurally complex materials is investigated by differential scanning calorimetry (DSC) and by thermogravimetric analysis (TGA). In addition, Fourier-transform infrared (FTIR) spectroscopy was used to investigate the chemical interactions between the different components. The endothermic gelatinization process (or water evaporation) observed by DSC in starch is also observed in the blends. Special attention was paid to the structural relaxation that can occur in the blends with poly(lactic acid) at body temperature that may change the physical properties of the material during its application as a biomaterial. At least three degradation mechanisms were identified in the blends by means of using TGA, being assigned to the mass loss due to the plasticizer leaching, and to the degradation of the starch and the synthetic polymer fractions. The non-isothermal kinetics of the decomposition processes was analyzed using two different integral methods. The analysis included the calculation of the activation energy of the correspondent reactions.
先前的研究表明，玉米淀粉与一些可生物降解的合成聚合物（聚（ε-己内酯）、醋酸纤维素、聚乳酸和乙烯-乙烯醇共聚物）的热塑性共混物在一系列生物医学应用中具有良好的应用潜力。在这项工作中，通过差示扫描量热法（DSC）和热重分析（TGA）研究了这些结构复杂材料的热行为。此外，利用傅里叶变换红外（FTIR）光谱研究了不同组分之间的化学相互作用。在共混物中也观察到了DSC在淀粉中观察到的吸热糊化过程（或水分蒸发）。特别关注了与聚乳酸共混物在体温下可能发生的结构弛豫，这可能会在其作为生物材料应用过程中改变材料的物理性能。通过使用TGA在共混物中确定了至少三种降解机制，分别归因于增塑剂浸出导致的质量损失以及淀粉和合成聚合物组分的降解。使用两种不同的积分方法分析了分解过程的非等温动力学。分析包括计算相应反应的活化能。
