Advanced Tube Theories for Predicting the Rheolllogy of Model and Commercial Polymers

技术概述流变学对聚合物结构（包括分子量分布和长链支化分布）比任何其它可测量的性质更敏感。因此，对精心选择的聚合物熔体和溶液进行流变学测量具有很大的动力，这将导致将流变学与聚合物分子量和支化分布联系起来的能力提高。提出了三个新项目。 首先，研究了臂和主链长度的多分散性对具有两个分支点和四个臂的缠结H聚合物的线性粘弹性的影响。最近的模型表明，H-支化的聚合物应该有流变性，是非常敏感的多分散性，因此，这些研究，沿着相应的理论工作，将允许这些理论进行强有力的测试，并有助于发展一个更准确的理论的分支点运动。 第二，使用陶氏化学公司的模型材料，将获得对分支点运动的高阶效应敏感的线性粘弹性数据，并将其用于测试现有算法（分级模型）精确预测这些数据的能力。第三个问题将是测试聚合物溶液中线性和非线性流变性质的通用标度原理，该原理认为，当以无量纲形式绘制时，所有这些性质在c/ce比率的固定值下测量时，浓度与缠结浓度叠加。这一概念将通过测量不同分子量的线性和非线性数据集，在几个固定的c/ce值，并通过将这些测试扩展到线性聚合物的二元共混物进行彻底测试。全球商业生产超过2000亿磅的聚合物，并将其成形为各种各样的产品。 成型过程取决于它们的流动性质或流变性，而流动性质或流变性又取决于分子特性，例如分子量分布和支化分布。因此，更好地定义聚合物分子结构和流变学之间的关系具有巨大的工业兴趣。拟议的工作将增加这种关系的知识，导致在分子水平上更好地设计聚合物。 从这笔赠款中获得的见解，以及来自同一个NSF项目的过去赠款，将有助于申请人与陶氏化学公司和宝洁公司的合作。今年出版的一本由提案人合著的新书《熔融聚合物的分子结构和流变学》包含了以前NSF赠款的工作，在新资助下开展的工作也将通过国际合作向美国工业界和海外进行宣传。 工作数据也将导致改进的商业软件包IRIS，用于预测聚合物熔体的流变性能，这是广泛使用的工业。

TECHNICAL SUMMARYRheology is more sensitive to polymer architecture, including molecular weight distribution and long-chain branching distribution, than is any other measurable property. Thus there is great motivation to carry out rheological measurements on well-chosen polymer melts and solutions that will lead to improved ability to link rheology to polymer molecular weight and branching distributions. Three new projects are proposed. First, the effects of polydispersity in arm and backbone length on the linear viscoelasticity of well defined entangled H polymers, which have two branch points and four arms, will be studied. Recent models show that H-branched polymers should have rheology that is very sensitive to polydispersity, so that these studies, along with corresponding theoretical work, will allow strong tests of these theories to be carried out, and help in the development of a more accurate theory of branch point motion. Second, using model materials from Dow Chemical Co., linear viscoelastic data will be obtained that will be sensitive to higher order effects of branch point motion and used to test the ability of an existing algorithm, the hierarchical model, to predict accurately these data. The third problem will be to test the principle of universal scaling of linear and nonlinear rheological properties in polymer solutions, which holds that all such properties, when measured at a fixed value of the ratio of c/ce, the concentration to the entanglement concentration superpose, when plotted in dimensionless form. This concept will be tested thoroughly by measuring sets of linear and nonlinear data for different molecular weights, at several fixed values of c/ce and by extending these tests to binary blends of linear polymers. NON-TECHNICAL SUMMARY Over 200 billion pounds of polymers are produced commercially worldwide, and shaped into a wide variety of products. The shaping processes depend on their flow properties, or rheology, which, in turn, depends on molecular characteristics, such as molecular weight distribution and branching distribution. Thus, there is a huge industrial interest in better defining the relationship between polymer molecular structure and rheology. The proposed work will increase knowledge of this relationship, leading to polymers that are designed better at the molecular level. Insights from this grant, and past grants from the same NSF program, will assist in collaborations the proposer has with Dow Chemical Co. and Procter and Gamble. A new book, co-authored by the proposer, Molecular Structure and Rheology of Molten Polymers, published this year, contains work from the previous NSF grants, and the work to be carried out under the new grant will similarly be well publicized, both to U.S. industry and overseas, through international collaborations. The work data will also lead to improvements in a commercial software package IRIS, for predicting rheological properties of polymer melts, that is used widely in industry.