Temperature dependence of crystalline transition of highly-oriented poly (L-lactide)/poly(D-lactide) blend: In-situ synchrotron X-ray scattering study
Temperature dependence of crystalline transition of highly-oriented poly (L-lactide)/poly(D-lactide) blend: In-situ synchrotron X-ray scattering study
复制标题
高度取向的聚（L-丙交酯）/聚（D-丙交酯）共混物的结晶转变的温度依赖性：原位同步加速器X射线散射研究
DOI：
10.1016/j.polymer.2012.11.076
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发表时间：
2013-01-24
期刊：
影响因子：
4.6
通讯作者：
Wang, Dujin
中科院分区：
文献类型：
--
作者：
Xiong, Zujiang;Liu, Guoming;Wang, Dujin
聚L-乳酸/聚D-乳酸（PLLA/PDLA）共混物的立体复合晶体（sc-晶体）的形成被认为是显著提高聚乳酸（PLA）耐热性的独特机会。本文采用同步辐射广角X射线散射（WAXS）、小角X射线散射（SAXS）和差示扫描量热法（DSC）研究了PLLA/PDLA拉伸膜中sc-晶体的动态形成和转变。还研究了在连续加热和冷却过程中均聚物中SC-晶体含量与α晶体（PLA的稳定相）竞争形成之间的相关性。结果表明，在室温下，PLLA/PDLA拉伸膜仅由α晶组成，但随着温度的升高，在不同温度下，高取向样品中分别从取向的非晶区和熔融的α晶中形成了两种sc晶群。此外，在随后的冷却过程中，形成了新类型的sc晶体和α晶体，其取向垂直于原始sc晶体。根据X射线散射和DSC数据，提出了一个关于sc晶体和α晶体的结晶和取向变化的示意性模型。(C)2012爱思唯尔有限公司保留所有权利。
Formation of stereocomplex crystals (sc-crystals) of poly(L-lactide)/poly(D-lactide) (PLLA/PDLA) blend has been recognized as a unique opportunity to dramatically improve the heat-resistant of poly(lactic acid) (PLA). In this study, we investigated the dynamic formation and transition of sc-crystals in PLLA/PDLA drawn film with a combination of in-situ synchrotron wide-angle X-ray scattering (WAXS), small-angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC). The correlation between sc-crystals content and the competing formation of alpha crystals (stable phase of PLA) in homopolymers during continuous heating and cooling processes was also studied. It was found that at room temperature, the original PLLA/PDLA drawn film consisted of only alpha crystals, however, with temperature increasing, two populations of sc-crystals were formed at different temperatures from the oriented amorphous region and the molten alpha crystals in the highly-oriented sample, respectively. Furthermore, new types of sc-crystals and alpha crystals with the orientation perpendicular to the original sc-crystals were formed during subsequent cooling process. On the basis of the X-ray scattering and DSC data, a schematic model for crystallization and oriented variation concerning sc-crystals and alpha crystals was proposed. (C) 2012 Elsevier Ltd. All rights reserved.