Experimental and Theoretical Studies of Polymeric Liquids in Extension-Dominated Fluids

9700034 Leal该奖项（由材料研究部和多学科活动办公室联合支持）的最终目标是开发一种预测基础，以描述线性链、柔性聚合物在拉伸或拉伸主导流动中的解的行为。主要的重点是解决方案是足够充分的角度，以信誉为基础的理论有望应用。提出的实验研究利用一种新型的流动单元组合，称为2辊和4辊轧机，旨在产生纯拉伸或拉伸主导的二维流动，也可以是稳定的，或依赖于时间的；光学技术可以探测链的结构和流动池内任意点的实际速度梯度。链的结构是从流体中光学各向异性程度的双色双折射测量中推断出来的。动态光散射的独特实现为稳定或瞬态流动提供了速度梯度的逐点测量。通过对boger型稀流体的全场流体动力学模拟，与理论模型进行了比较。对于基于重复的单分散和双分散纠缠溶液模型，将测量的生物折射数据与使用测量的速度梯度数据作为输入的模型预测进行比较。%%%%从技术的角度来看，预测聚合物液体在拉伸流动中的行为的能力将使我们能够理解材料特性和加工之间的关系。从教育的角度来看，GOALI项目提供了对普通博士课程的改进。研究生将在埃克森公司研究实验室居住长达一年，在那里他们将直接与Scott Milner一起工作，并参观位于Baytown的埃克森研究实验室，那里正在进行与本项目的基本目标直接相关的聚合物合成和聚合物加工问题的研究。* * *

9700034 Leal The ultimate objective of this GOALI award (supported jointly by the Division of Materials Research and the Office of Multidisciplinary Activities) is the development of a predictive basis to describe the behavior of solutions of linear-chain, flexible polymers in flows that are either extensional or extension-dominated. The primary emphasis is on solutions that are sufficiently ent angled that reptation-based theories are expected to apply. The proposed experimental studies utilize a novel combination of flow cells, known as 2- and 4- roll mills, that are designed to produce pure extensional, or extension-dominated, two-dimensional flows, that can also be either steady, or time-dependent; and optical techniques that can probe the chain configuration and the actual velocity gradient at any point within the flow cell. Chain configuration is inferred from two-color birefringence measurements of the degree of optical anisotropy in the fluid. A unique implementation of dynamic light scattering provides a pointwise measure of the velocity gradient for either steady or transient flows. Comparisons with theoretical models are made via full-field fluid dynamics simulations for the dilute, Boger-type fluids. For reptation-based models of monodisperse and bi-disperse entangled solutions, measured biorefringence data is compared with model predictions using the measured velocity gradient data as input. %%%% From a technological point of view, the ability to predict the behavior of polymeric liquids in extensional flows would allow an understanding of the relationship between material characteristics and processing. From an educational standpoint, this GOALI project offers enhancements to the normal Ph.D. program. Graduate students will spend up to a year in residence at the Exxon Corporate Research Laboratory, where they will work directly with Scott Milner, as well as visiting the Exxon Research Labs at Baytown where work is being carried out on both polymer synthesis and polymer processing issues that are directly related to the fundamental objectives of this project. ***