摘要聚乳酸是一种脂肪族聚酯类化合物，它来源于可再生作物，经过酶分解、乳酸菌 发酵等步骤最终获得。其废弃的产品埋在土壤中通过微生物作用 6～12 个月后便可以 完全分解为 CO2 和 H2O，不仅不会对环境造成污染，还可以给植物提供养料，整个 过程绿色可持续，所以对于石油资源越来越稀缺的今天，有着许多高分子材料不能比 拟的优势。81236

本文使用浓度为 2%的 PLLA/CH3Cl 溶液，滴在玻璃片上常温静置，制成无纤维 和有纤维两种 PLLA 膜，再使用恒温热台加热熔融，并结晶成晶体，研究在不同结晶 温度下和有无纤维诱导条件下的晶体形貌。通过偏光显微镜 POM、差示扫描量热仪 DSC、拉曼 Raman 等实验设备对晶型晶貌、大小等进行了研究。

结果表明：在无纤维剪切诱导的情况下，当结晶温度从 120℃升高到 145℃时， PLLA 球晶尺寸呈指数级增长，结晶速度先变大后变小。当结晶温度为 135℃时，结 晶速度处于最大值，然后逐渐变慢导致晶体生长的过程边长。通过 DSC 测试发现当 结晶温度升高时，PLLA 的熔点升高；当结晶温度降低时，PLLA 熔点降低。在纤维 剪切诱导结晶的情况下会有柱晶产生，柱晶由 α 和 α’构成；并且当结晶温度越高时， 越容易形成较粗的柱晶，当结晶温度越低时，生成的柱晶越细或几乎不产生。

毕业论文关键字：左旋聚乳酸（PLLA），结晶行为，球晶形貌，柱晶

Abstract PLA is an aliphatic polyester compound, which comes from renewable crops, finally obtained after enzymatic decomposition and lactic acid fermentation。 If its products buried in the soil after abandoned, it can be completely degraded to CO2 and H2O discharging to the air after 6~12 months in the role of microorganisms。 Not only will not cause any pollution to the environment, but also can become plant food。 As a result, the oil resource is becoming more and more intense today, it has the advantage than a lot of polymer materials。

In this paper, PLLA was dissolved in CH3Cl, formulated solution in a concentration of 2%。 Then drop to slide at room temperature evaporation,and make two kinds of PLLA films with fiber or not。 Last melt and crystallize。 We studied how different temperatures and the presence or absence of fibers impact on crystal morphology。 The crystal characteristic was tested by POM, DSC and Raman。

In the result, without fiber shear, PLLA spherulite size grows exponentially, crystallization rate is changing form fast to slow,when the crystallization temperature was increased from 120 ℃ to 145 ℃。 The crystallization rate reaches the maximum, when the   crystallization

temperature is 135℃。 The melting point of poly lactic acid was found to decrease with  the

increase of crystallization temperature by DSC test。 In the case of fiber shear induced crystallization will produce crystal column, constituting α and α '。 When the crystallization temperature is higher, it’s more likely to form a more coarse columnar crystal。 Lower temperatures has opposite result。

Keywords:Poly(L-lactic acid), crystallization behavior, spherulitic morphology， trans-crystalline

目录

第一章 绪论 1

1。1  引言 1

1。2  聚乳酸 1

1。2。1 聚乳酸的理化性质 1

1。2。2 聚乳酸晶型 2

1。2。3