..魏太演 Crystallization Behavior and Isothermal Crystallization Kinetics..pdf

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..魏太演 Crystallization Behavior and Isothermal Crystallization Kinetics..pdf

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..魏太演 Crystallization Behavior and Isothermal Crystallization Kinetics.

Crystallization Behavior and Isothermal Crystallization Kinetics of PLLA Blended with Ionic Liquid, 1-Butyl-3-methylimidazolium Dibutylphosphate Taiyan Wei,1,2 Sujuan Pang,1,2 Nai Xu,1,2 Lisha Pan,1,2 Zhengqing Zhang,1,2 Ruizhang Xu,1,2 Nansong Ma,1,2 Qiang Lin3 1College of Materials and Chemical Engineering, Hainan University, Hainan, Haikou 570228, China 2Hainan Provincial Fine Chemical Engineering Research Center, Hainan University, Hainan, Haikou 570228, China 3College of Chemistry and Chemical Engineering, Hainan Normal University, Hainan, Haikou 571158, China Correspondence to: N. Xu (E - mail: xunai1978@) ABSTRACT: The crystallization behavior and isothermal crystallization kinetics of neat poly(L-lactic acid) (PLLA) and PLLA blended with ionic liquid (IL), 1-butyl-3-methylimidazolium dibutylphosphate, were researched by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and wide angle X-ray diffraction (WXRD). Similar to the non-isothermal crystallization behav- ior of neat PLLA, when PLLA melt was cooled from 200 to 20C at a cooling rate of 10C min21, no crystallization peak was detected yet with the incorporation of IL. However, the glass transition temperature and cold crystallization temperature of PLLA gradually decreased with the increase of IL content. It can be attributed to the significant plasticizing effect of IL, which improved the chain mobility and cold crystallization ability of PLLA. Isothermal crystallization kinetics was also analyzed by DSC and described by Avrami equation. For neat PLLA and IL/PLLA blends, the Avrami exponent n was almost in the range of 2.5–3.0. It is found that t1/2 reduced largely, and the crystallization rate constant k increased exponentially with the incorporation of IL. These results show that the IL could accelerate the overall crystallization rate of PLLA due to its plasticizing effect. In addition, the dependences of crystalliza- tion rate on crystallization temperature and IL conten