Experimental and Theoretical Studies of Concentrated PolymerSolutions in Strong Flows

迫切需要开发一种技术，使聚合物能够以更快的速度加工，并导致聚合物材料具有更高的分子取向程度。这些进展将使现有工艺更具竞争力，并将增加制造有价值的新产品的前景。如果在高应变率下研究聚合物的实验技术得到改进，并利用由此产生的信息来发展对聚合物液体如何流动的微观理解，这些目标就有可能实现。本项目旨在提供这方面的基本知识。它描述了在商业加工操作中常见的含有剪切和拉伸混合物的流动类型下的聚合物液体的分子和流体力学的实验研究工作。实验将使用一系列技术来研究影响流变学响应的最重要的参数：缠结密度和分子量分布。建立这种具有良好分子结构特征的材料的数据库是必要的起点。这样获得的分子理解将被用于继续开发项目中描述的模型。最终目标是详细了解在这些条件下存在的高度非线性响应，并利用这些信息设计新的加工程序，以优化聚合物的宏观性能。这项研究由材料研究部的聚合物项目和化学和热力系统部门的流体、颗粒和液压系统项目共同支持。

A critical need exists to develop the technology that will allow processing polymers at faster speeds and that will result in polymeric materials with higher degrees of molecular orientation. Such advances will make existing processes more competitive and will increase the prospects for manufacturing valuable new products. It is likely that these goals can be reached if experimental techniques for studying polymers at high strain rates are improved and the resulting information is used to develop a microscopic understanding of how polymer liquids flow. This project is intended to provide this fundamental knowledge. It describes experimental research work on the molecular and fluid mechanics of polymeric liquids subjected to flow types that contain a mixture of shear and extension typically found in commercial processing operations. The experiments will investigate, using a range of techniques, the most important parameters affecting the rheological response: entanglement density and molecular-weight distribution. A data base of this type on materials that have well-characterized molecular structures is the necessary starting point. The molecular understanding so obtained will be used to continue the development of models described in the project. The ultimate goal is to have a detailed understanding of the highly nonlinear response that exits under these conditions and to use this information to devise new processing procedures that will optimize the macroscopic properties of polymers. This research is jointly supported by the Polymers Program in the Division of Materials Research and the Fluid, Particulate and Hydraulic Systems Program of the Division of Chemical and Thermal Systems.