Glass Transition Dynamics of Poly(L‐lactic acid) during Isothermal Crystallisation Monitored by Real‐Time Dielectric Relaxation Spectroscopy Measurements
Glass Transition Dynamics of Poly(L‐lactic acid) during Isothermal Crystallisation Monitored by Real‐Time Dielectric Relaxation Spectroscopy Measurements
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通过实时介电弛豫光谱测量监测等温结晶过程中聚（L-乳酸）的玻璃化转变动力学
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发表时间：
2005
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通讯作者：
J. Mano
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作者：
Madalena Dionísio;M. T. Viciosa;Yaming Wang;J. Mano
使用介电弛豫光谱来监测 80°C 下聚（L-乳酸）（PLLA）结晶度的发展。主损耗峰向较低频率的连续移动是根据三个弛豫过程的演变进行建模的：块状（非限制性）非晶相的 α 过程、受晶体结构影响的非晶部分的 α 过程和 β 弛豫。研究发现，形状参数和损耗峰的位置在结晶过程中基本恒定，只是介电强度发生变化。这表明（i）两个分段动力学过程独立发展，并且（ii）（较慢的）受限非晶相的动力学特征在结晶过程中不会改变。光学显微镜结果表明，球晶形态的演变与α过程的介电强度之间存在相关性。
Dielectric relaxation spectroscopy was used to monitor the development of crystallinity in poly(L-lactic acid) (PLLA) at 80 °C. The continuous shifting of the main loss peak towards lower frequencies was modelled considering the evolution of three relaxation processes: the α-process of the bulk-like (non-restricted) amorphous phase, the α-process of the amorphous fraction influenced by the crystalline structure and the β-relaxation. It was found that the shape parameters and the position of the loss peaks are essentially constants during crystallisation, just with their dielectric strengths varying. This indicates that (i) the two segmental dynamics process develops independently and (ii) the dynamics features of the (slower) confined amorphous phase do not change during crystallisation. Optical microscopy results showed that a correlation exists between the evolution of the spherolitic morphology and the dielectric strength of the α-processes.