Experimental and Theoretical Studies of Concentrated PolymerSolutions in Strong Flows

目前迫切需要开发能够以更快的速度加工聚合物的技术，从而生产出具有更高分子取向度的聚合物材料。这些进步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。如果在高应变速率下研究聚合物的实验技术得到改进，并且所得到的信息用于发展对聚合物液体如何流动的微观理解，那么这些目标很可能可以实现。本项目旨在提供这些基本知识。它描述了聚合物液体的分子和流体力学的实验研究工作，这些流动类型包含剪切和拉伸的混合物，通常在商业加工操作中发现。实验将使用一系列技术，研究影响流变响应的最重要参数：缠结密度和分子量分布。这类具有良好分子结构特征的材料的数据库是必要的起点。由此获得的分子理解将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处理程序，以优化聚合物的宏观性能。这项研究是由材料研究部门的聚合物项目和化学和热系统部门的流体、颗粒和液压系统项目共同支持的。

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.