【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。更多还原

【Abstract】 In this work,amorphous PLLA films and crystalline PLLA samples were prepared at different crystallization temperatures(80-160℃).The crystal modifications and crystallization morphologies of PLLA samples were studied by Infrared spectroscopy(FT-IR),X-ray diffraction(XRD),and polarized optical micrographs(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 α′-crystal is mainly produced for the crystal structure of PLLA samples;however,at crystallization temperature ≥ 120℃,the order α-crystals PLLA are mainly proposed;whe the crystallization temperature is between 100 to 120℃,both α′-and α-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 increasing the crystallization temperature.It was found that the disorder-to-order(α′-to α-crystalline form) transition occures with increasing crystallization temperature above 120℃.更多还原