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Aging-controlled crystallization of poly(lactic acid).Part 3: Control of crystallization, structure and properties of injection moldings of poly(lactic acid) by controlled crystal nucleation during and after the injection-molding process

聚乳酸的老化控制结晶。第 3 部分：通过注塑过程中和注塑后控制晶体成核来控制聚乳酸注塑件的结晶、结构和性能

基本信息

批准号：
261899164
负责人：
Professor Dr.-Ing. René Androsch
金额：
--
依托单位：
Leibniz-Institut für Polymerforschung Dresden (IPF)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2014
资助国家：
德国
起止时间：
2013-12-31 至 2021-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/261899164?language=en
关键词：
Aging controlled crystallization poly lactic

项目摘要

In the first part of the project Aging-controlled crystallization of poly (lactic acid), the kinetics of crystal nucleation of poly (L-lactic acid) (PLLA) during both cooling of the quiescent melt as well as annealing/storage of amorphous samples at temperatures lower than the glass transition temperature was quantified, taking into account the thermal history (cooling rate, annealing temperature and annealing time) and the molecular architecture (molar mass, stereo defect concentration). It was found that the crystal nuclei, evident in the glassy state after a pre-defined thermal treatment and being controllable in their number, cause rapid crystallization at temperatures only slightly higher than the glass transition temperature and generation of a fine-spherulitic semicrystalline morphology which is advantageous for many applications.In the second part of the project, the investigations/research about crystal nucleation in PLLA is intended to be completed by additional evaluation of the influence of shear deformation of the melt. Deformation of the melt and, consequently, the resulting orientation of macromolecules lead in case of many polymers to generation of crystal nuclei, which accelerate crystallization. Systematic investigation of shear-induced crystal nucleation in case of PLLA was not performed yet. In this project, therefore, shear-induced crystal nucleation and the stability of such crystal nuclei formed under shear conditions will be analyzed for PLLA of different molar mass and different D-isomer concentration within model experiments. Together with the results obtained in the first part of the project, it will then be possible to precisely forecast crystallization of PLLA of different molecular architecture and thermo-rheological history (cooling rate, shear, aging below the glass transition temperature). Such information then can be used, for example, to optimize the crystallization process of otherwise only slowly crystallizing PLLA in real polymer processing.

在老化控制聚乳酸结晶项目的第一部分，量化了聚乳酸(PLLA)在静态熔体冷却和低于玻璃化转变温度的非晶态样品的退火/储存过程中的结晶成核动力学，考虑了热历史(降温速度、退火温度和退火时间)和分子结构(摩尔质量、立体缺陷浓度)。研究发现，晶核在经过预先定义的热处理后处于玻璃态且数量可控，在仅略高于玻璃化转变温度的温度下导致快速晶化，并产生细小的球晶半晶形态，这对许多应用是有利的。在项目的第二部分，关于PLLA中晶体成核的调查/研究旨在通过对熔体剪切变形的影响的额外评估来完成。在许多聚合物的情况下，熔体的变形以及由此产生的大分子取向导致晶核的产生，从而加速结晶。在PLLA的情况下，剪切诱导结晶成核的系统研究还没有进行。因此，本项目将在模型实验中对不同摩尔质量和不同D-异构体浓度的PLLA进行剪切诱导成核和在剪切条件下形成的晶核的稳定性分析。结合项目第一部分的结果，将有可能准确预测不同分子结构和热流变史(降温速度、剪切、玻璃化转变温度以下的老化)的PLLA的结晶。例如，这些信息可以用来优化PLLA的结晶过程，否则在实际的聚合物加工中只能缓慢结晶。