光学纯度对聚左旋乳酸结晶与熔融行为的影响

doi:10.11944/j.issn.1000-0518.2016.08.150423

摘要/Abstract

摘要：

通过示差扫描量热仪(DSC)和广角X射线衍射仪(WAXD)研究了聚左旋乳酸(PLLA)的光学纯度(91.6%、93.3%、94.0%、97.0%、98.4%)对聚乳酸结晶和熔融行为的影响。在非等温结晶过程中,随着光学纯度的提高,聚乳酸的结晶峰值温度、熔点、熔融焓均提高。在等温结晶过程中,PLLA的半结晶时间(t_1/2)随着光学纯度的增加而减少,在结晶温度100~110 ℃区间内半结晶时间均达到最小值;含有不同光学纯度PLLA的Avrami指数n≈3,表明光学纯度的变化不能改变聚乳酸以三维球晶生长的异相成核机理。随着光学纯度的增加,聚乳酸δ-晶型转变为α-晶型的临界温度升高。聚乳酸的结晶和熔融行为对光学纯度具有依赖性。

关键词: 聚左旋乳酸, 光学纯度, 结晶

Abstract:

In both nonisothermal and isothermal treatments, crystallization and melting behaviors of poly(L-lactic acid)(PLLA) with different optical purities(91.6%, 93.3%, 94.0%, 97.0%, 98.4%) were investigated by differential scanning calorimetery(DSC) and wide-angle X-ray diffraction(WAXD).With the increase of optical purities of PLLA, the crystallization rate, the melting enthalpy, crystallization temperature and melting point increase. The Avrami index(n) is about 3, indicating a three-dimensional spherulitic growth on heterogeneous nuclei during the isothermal process. The crystalline structure of PLLA is independent on the variation of optical purities of PLLA. However, the critical temperature for crystal formation from δ-form to α-form crystals increases during the isothermal crystallization process with optical purities increasing of PLLA. All the results show that the crystallization and melting behaviors are dependent on the optical purities of PLLA.

Key words: poly(L-lactic acid), optical purity, crystallization

项盛, 邵俊, 冯立栋, 李杲, 陈学思, 边新超, 刘凤岐. 光学纯度对聚左旋乳酸结晶与熔融行为的影响[J]. 应用化学, 2016, 33(8): 887-893.

XIANG Sheng, SHAO Jun, FENG lidong, LI Gao, CHEN Xuesi, BIAN Xinchao, LIU Fengqi. Effect of Optical Purities on the Crystallization and Melting Behaviors of Poly(L-lactic acid)[J]. Chinese Journal of Applied Chemistry, 2016, 33(8): 887-893.

参考文献

[1]	Drumright R E,Gruber P R,Henton D E. Polylactic Acid Technology[J]. Adv Mater,2000,12(23):1841-1846.
[2]	Saeidloua S,Huneaulta M A,Li H B,et al.Poly(lactic acid) Crystallization[J]. Prog Polym Sci,2012,37(12):1657-1677.
[3]	Tian H Y,Tang Z H,Zhuang X L,et al.Biodegradable Synthetic Polymers:Preparation, Functionalization and Biomedical Application[J]. Prog Polym Sci,2012,37(2):237-280.
[4]	Anderson K S,Schreck K M,Hillmyer M A. Toughening Polylactide[J]. Polym Rev,2008,48(1):85-108.
[5]	Raquez J M,Habibi Y,Murariu M,et al.Polylactide(PLA)-based Nanocomposites[J]. Prog Polym Sci,2013,38(10):1504-1542.
[6]	Fan Y J,Nishida H,ShiraiY,et al. Control of Racemization for Feedstock Recycling of PLLA[J]. Green Chem,2003,5(5):575-579.
[7]	Tsukegi T,Motoyama T,Shirai Y,et al.Racemization Behavior of L,L-lactide During Heating[J]. Polym Degrad Stab,2007,92(4):552-559.
[8]	Feng L D,Sun B,Bian X C,et al.Determination of D-lactate Content in Poly(lactic acid) Using Polarimetry[J]. Polym Test,2010,29(7):771-776.
[9]	Bai H W,Huang C M,Xiu H,et al.Significantly Improving Oxygen Barrier Properties of Polylactide via Constructing Parallel-Aligned Shish-Kebab-Like Crystals with Well-Interlocked Boundaries[J]. Biomacromolecules,2014,15(4):1507-1514.
[10]	Harris A M,Lee E C. Improving Mechanical Performance of Injection Molded PLA by Controlling Crystallinity[J]. J Appl Polym Sci,2008,107(4):2246-2255.
[11]	Zhou D D,Shao J,Li G,et al.CrystallizationBehavior of PEG/PLLA Block Copolymers:Effect of the Different Architectures and Molecular Weights[J]. Polymer,2015,62(7):70-76.
[12]	Zhang J M,Tashiro K,Tsuji H,et al.Disorder-to-Order Phase Transition and Multiple Melting Behavior of Poly(L-lactide) Investigated by Simultaneous Measurements of WAXD and DSC[J]. Macromolecules,2008,41(4):1352-1357.
[13]	Eling B,Gogolewski S,Pennings A J. Biodegradable Materials of Poly(L-lactic acid):1.Melt-spun and Solution-spun Fibres[J]. Polymer,1982,23(11):1587-1593.
[14]	Cartier L,Okihara T,Ikada Y,et al.Epitaxial Crystallization and Crystalline Polymorphism of Polylactides[J]. Polymer,2000,41(25):8909-8919.
[15]	Yasuniwa M,Tsubakihara S,Iura K,et al. Crystallization Behavior of Poly(L-lactic acid)[J]. Polymer,2006,47(21):7554-7563.
[16]	Shao J,Xiang S,Bian X C,et al.Remarkable Melting Behavior of PLA Stereocomplex in Linear PLLA/PDLA Blends[J]. Ind Eng Chem Res,2015,54(7):2246-2253.
[17]	CHENG Haibo,CHEN Xuesi,XIAO Haihua,et al.Promotion of Crystallization in Linear Polylactide by Multiarm-polylactide[J]. Chinese J Appl Chem,2010,27(7):754-758(in Chinese). 程海波,陈学思,肖海华,等. 多臂聚乳酸对线型聚乳酸结晶的促进作用[J]. 应用化学,2010,27(7):754-758.
[18]	ZHANG Han,SUN Zhiqiang,PANG Xuan,et al.Preparation and Properties of Blends from Poly(ε-caprolacton-ran-L-lactide) Random Copolymer and Amorphous Poly(lactide acid)[J]. Chinese J Appl Chem,2015,32(11):1268-1274(in Chinese). 张涵,孙志强,庞烜,等. 聚(ε-己内酯-L-丙交酯)无规共聚物与聚乳酸共混材料的制备与性能[J]. 应用化学,2015,32(11):1268-1274.
[19]	Li H B,Huneault M A. Effect of Nucleation and Plasticization on the Crystallization of Poly(lactic acid)[J]. Polymer,2007,48(23):6855-6866.
[20]	Huang J,Lisowski M S,Runt J. Crystallization and Microstructure of Poly(L-lactide-co-meso-lactide) Copolymers[J]. Macromolecules,1998,31(8):2593 2599.
[21]	Ahmed J,Zhang J X, Song Z, et al. Thermal Properties of Polylactides:Effect of Molecular Mass and Nature of Lactide Isomer[J]. J Therm Anal Calorim,2009,95(3):957-964.