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，以描述直链柔性聚合物溶液在拉伸或拉伸主导的流动中的行为。主要强调的是有足够角度的解决方案，以使基于旋转的理论有望应用。拟议的实验研究利用了一种新的流动池组合，称为二辊和四辊轧机，旨在产生纯拉伸或拉伸主导的二维流动，这种流动也可以是稳定的，也可以是时间相关的；以及光学技术，可以探测流动池内任何点的链结构和实际速度梯度。从流体中光学各向异性程度的双色双折射测量推断出链的构型。动态光散射的独特实现提供了对稳定或瞬变流动的速度梯度的逐点测量。通过对稀薄Boger类流体的全场流体动力学模拟，与理论模型进行了比较。对于基于旋转的单分散和双分散纠缠溶液模型，将测量的生物干涉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人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，这个GOALI项目提供了对普通博士项目的增强。研究生将在埃克森公司研究实验室驻留长达一年，在那里他们将直接与Scott Milner合作，并参观位于贝敦的埃克森研究实验室，在那里正在开展与该项目基本目标直接相关的聚合物合成和聚合物加工问题的工作。***

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. ***