Crystallization Behavior of Asymmetric PLLA/PDLA Blends

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• 作者：Jingru Sun ; Haiyang Yu ; Xiuli Zhuang ; Xuesi Chen ; Xiabin Jing
• 刊名：Journal of Physical Chemistry B
• 出版年：2011
• 出版时间：March 31, 2011
• 年：2011
• 卷：115
• 期：12
• 页码：2864-2869
• 全文大小：867K
• 年卷期：v.115,no.12(March 31, 2011)
• ISSN：1520-5207

文摘

The effects of the addition of poly(d-lactide) (PDLA) on the crystallization behavior of poly(l-lactide)(PLLA) were investigated by means of differential scanning calorimetry (DSC) and temperature-dependent X-ray diffraction(XRD). When the blends were cooled from different temperatures (250, 240, and 190 掳C) at the rate of cooling of 5 掳C/min, stereocomplex (sc) crystallites could stay at diverse states. Accordingly, the stereocomplexes acted as a nucleation agent exerting distinct effects on PLLA crystallization. The speculated mechanisms of the stereocomplex formation and the effectiveness as a nucleating agent are schematically described. Moreover, temperature-dependent XRD was carried out to further investigate the melt-crystallization behavior of PLLA/PDLA blends in real time. Temperature-dependent XRD results indicated that even at 240 掳C the stereocomplex crystallites in all blend samples existed clearly, which could not be detected by DSC. These XRD results further suggest that the onset T_c values for the PLLA 伪-form crystals formation were 160, 120, 140, and 160 掳C, respectively, for neat PLLA, PLLA/PDLA 95/5, 90/10, and 80/20 as well as 70/30 samples.