以左旋聚乳酸（PLLA）为原料,制备了无定型PLLA膜及无定型PLLA在不同温度下等温结晶的样品。利用红外光谱（FT-IR）、X射线衍射（XRD）和偏光显微镜（POM）分析了结晶温度的改变对PLLA样品的晶体改性及晶体形貌的影响。研究结果表明,结晶温度的改变对PLLA样品的晶体结构、晶型转变及晶粒形貌特征产生了较大的影响。当结晶温度低于100℃时,PLLA主要以无序的α＇-晶型存在;随着结晶温度的增加,PLLA的晶体结构和晶型开始转变,当结晶温度超过120℃后,PLLA主要以α-晶型的形式存在;而当结晶温度在100～120℃范围内,则形成的是α＇-与α-晶型PLLA的混合形式存在。另一方面,POM照片测试结果表明,随着结晶温度的升高,PLLA的晶体形貌发生了改变,晶粒尺寸随温度的增加而增加,结晶速度增加,晶粒数量减少,PLLA晶体由α＇-向α-晶型发生了转变。
In this work, amorphous PLLA films and crystalline PLLA samples were prepared at different crys- tallization temperatures （80-160℃）. The crystal modifications and crystallization morphologies of PLLA sam- ples were studied by Infrared spectroscopy （FT-IR）, X-ray diffraction （XRD）, and polarized optical micro- graphs （POM）. The results demonstrated that the change of crystallization temperature has a great effect on the crystal structure, phase transition, and crystallization morphology of PLLA. At crystallization temperature 〈100℃, disorder aP-crystal is mainly produced for the crystal structure of PLLA samples; however, at crystal- lization temperature ≥ 120℃, the order a-crystals PLLA are mainly proposed; whe the crystallization tempera- ture is between 100 to 120℃, both a- and a-forms coexist. Besides, the crystal morphologies of PLLA samples were illustrated, and it was found that the crystal size increases and the number of spherulite decreases with in- creasing the crystallization temperature. It was found that the disorder-to-order （a-to a-crystalline form） tran- sition occures with increasing crystallization temperature above 120℃.
参考文献
| [1] | Dorgan JR.;Palade LL.;Cicero J.;Lehermeier HJ. .Polylactides: Properties and prospects of an environmentally benign plastic from renewable resources[J].Macromolecular symposia,2001(0):55-66. |
| [2] | Mezghani K.;Spruiell JE. .High speed melt spinning of poly(L-lactic acid) filaments[J].Journal of Polymer Science, Part B. Polymer Physics,1998(6):1005-1012. |
| [3] | Lwata T;Doi Y .[J].Macromolecules,1988,31(08):2461-2467. |
| [4] | De S P;Kovacs A .[J].Biopolymers,1968,6:299-306. |
| [5] | Eling B;Gogolewski S;Pennings A .[J].Polymer,1982,23(11):1587-1593. |
| [6] | Hoogsteen W;Postema A R;Pennings A J et al.[J].Macromolecules,1990,23(02):634-642. |
| [7] | Cartier L.;Ikada Y.;Tsuji H.;Puiggali J.;Lotz B.;Okihara T. .Epitaxial crystallization and crystalline polymorphism of polylactides[J].Polymer: The International Journal for the Science and Technology of Polymers,2000(25):8909-8919. |
| [8] | Pan PJ;Zhu B;Kai WH;Dong T;Inoue Y .Polymorphic transition in disordered poly(L-lactide) crystals induced by annealing at elevated temperatures[J].Macromolecules,2008(12):4296-4304. |
| [9] | Zhang JM;Duan YX;Sato H;Tsuji H;Noda I;Yan S;Ozaki Y .Crystal modifications and thermal behavior of poly(L-lactic acid) revealed by infrared spectroscopy[J].Macromolecules,2005(19):8012-8021. |
- 下载量()
- 访问量()
- 您的评分：
-
10%
-
20%
-
30%
-
40%
-
50%