中文摘要：

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。

英文摘要：

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℃.