Isothermal and Nonisothermal Cold Crystallization Behaviors of Asymmetric Poly(L-lactide)/Poly(D-lactide) Blends
Isothermal and Nonisothermal Cold Crystallization Behaviors of Asymmetric Poly(L-lactide)/Poly(D-lactide) Blends
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DOI：
10.1021/ie302447e
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发表时间：
2012-12-12
影响因子：
4.2
通讯作者：
Han, Changyu
中科院分区：
文献类型：
--
作者：
Li, Yi;Han, Changyu
研究了不对称聚L-乳酸（PLLA）/聚D-乳酸（PDLA）共混物在PDLA含量为0- 20wt%时的等温和非等温冷结晶行为。通过差示扫描量热法和广角X射线衍射证实了共混物中立体复合物的形成。对于纯PLLA及其共混物，整体等温冷结晶速率随着结晶温度的增加而增加;此外，PLLA的整体等温冷结晶速率在共混物中比在纯PLLA中更快，表明共混物中形成的立体复合物的成核剂效应。PLLA的结晶机制和晶体结构保持不变，尽管PDLA负载。对于非等温冷结晶，PLLA的结晶过程加快，通过增加升温速率和PDLA负载量高达10重量%。Ozawa方程不能很好地描述结晶过程，而Tobin方程在相对结晶度0- 75%范围内能很好地描述结晶过程。
Isothermal and nonisothermal cold crystallization behaviors of asymmetric poly(L-lactide) (PLLA)/poly(D-lactide) (PDLA) blends at PDLA loadings of 0-20 wt % were investigated in this work. Formation of the stereocomplex in the blends was confirmed by differential scanning calorimetry and wide-angle X-ray diffraction. For both neat PLLA and its blends, the overall isothermal cold crystallization rates increase with increasing crystallization temperature; moreover, the overall isothermal cold crystallization rates of PLLA are faster in the blends than in neat PLLA, indicative of the nucleating agent effect of the stereocomplex formed in the blends. Crystallization mechanism and crystal structure of PLLA remain unchanged despite the PDLA loading. For the nonisothermal cold crystallization, the crystallization process of PLLA is accelerated by increasing both heating rate and the PDLA loading up to 10 wt %. The Ozawa equation failed to fit the crystallization process, while the Tobin equation could describe it well in the relative degree of crystallization range of 0-75%.