尼龙薄膜双向拉伸过程中的结晶机理与流变行为研究

Abstract：Tailoring the crystallization and orientation behavior of nylon film in the process of biaxial stretching is the key to optimize the formulation and processing technology. Domestic modified nylon resin and foreign special nylon resin are selected as research objects: (1) developing small biaxial stretching experimental device, and setting up experimental platform for studying crystallization, orientation, rheological behavior during the biaxial stretching (2) analyzing the coupling relationship among crystal growth, crystal morphology, crystal orientation, crystallinity and multi-dimensional processing parameters (stretching temperature, stretching method, stretching speed, stretching ratio, etc.) of thin film during biaxial stretching process, and revealing the influence of microstructure evolution on the final performance and quality of thin films. (3) investigatingthe stress-strain behaviors of the film under different stretching conditions and establishing the rheological model during the film stretching as well as further explaining the rheological mechanism during the biaxial stretching through the combination of rheological behavior and crystallization behavior. The above studies provide theoretical guidelines for the in-depth analysis of the dynamic relationship among material, processing, structure and performance during the biaxial stretching, so as further for the development of nylon resin for biaxial stretching and the optimization of biaxial stretching process.

调控尼龙薄膜双向拉伸过程中的结晶及取向行为是优化材料配方和加工工艺的关键，直接影响制品的结构与性能。分别选取国产改性尼龙树脂和国外专用尼龙树脂为研究对象:（1）自行研制双向拉伸小型实验装置，建立研究双向拉伸过程中结晶、取向、流变行为的实验平台。（2）分析薄膜双向拉伸过程中晶体生长、晶体形态、晶体取向、结晶速率、结晶度与多维加工参数（拉伸温度、拉伸方式、拉伸速度、拉伸比等）的耦合关系，揭示微观结构及其演化最终对薄膜性能和品质的影响规律。（3）考察不同拉伸条件下薄膜应力—应变的变化规律，建立薄膜拉伸过程的流变学模型；流变行为与结晶行为相结合，进一步解释双向拉伸过程中的流变学机理。上述研究为深入分析双向拉伸过程中材料—加工—结构—性能之间的动态关系，进而为适用于双向拉伸的尼龙树脂的开发和双向拉伸生产工艺的优化提供理论指导。

由于高分子的长链特性，外场诱导分子链取向并形成一定的聚集态结构，是改善高分子制品性能的有效方法。针对尼龙薄膜双向拉伸过程中的基础科学问题，本项目以双向拉伸实验装置为平台，系统分析了尼龙薄膜在双向拉伸过程中的结晶、取向、流变等行为及其与拉伸工艺参数的耦合关系，实现了尼龙薄膜经双向拉伸后的微观结构及其制品性能的调控，为优化加工工艺及产品性能提供了理论依据。具体包括：（1）研制了薄膜双向拉伸小型实验装置，建立了研究双向拉伸过程中结晶、取向、流变行为的实验平台，可实现不同加工条件下双向拉伸薄膜的制备和相关实验数据的测量与采集。（2）分析了尼龙薄膜双向拉伸过程中晶体生长、晶体形态、晶体取向、结晶速率、结晶度与多维加工参数的耦合关系，揭示了微观结构及其演化最终对薄膜性能和品质的影响规律。（3）考察了尼龙薄膜双向拉伸过程中的流动与变形规律，既涉及薄膜应力-应变非线性关系的宏观加工流变，也包括薄膜内部分子链取向、松弛及其流动的微观结构流变。（4）创新了双向拉伸尼龙薄膜的材料改性和配方设计，提升了尼龙薄膜的性能，制备的高抗冲尼龙薄膜、高阻隔尼龙薄膜等产品已应用于聚合物锂离子电池软包、药品泡罩包装、食品包装、重物包装等领域。项目研究期间，申请专利并授权12件，其中发明专利9件；发表论文25篇，其中SCI论文15篇、EI论文4篇；产业化成果先后荣获省部级科技进步一等奖和二等奖。