The Effect of Particle-polymer Interactions on the Rheology and Structure of Dilute Particle-filled Polymeric Liquids

颗粒-聚合物相互作用对稀颗粒填充聚合物液体流变学和结构的影响

基本信息

批准号：
1803156
负责人：
Donald Koch
金额：
$ 31.73万
依托单位：
Cornell University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-07-01 至 2021-06-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1803156&HistoricalAwards=false
关键词：
Effect Particle polymer Interactions Rheology

项目摘要

Solutions of polymer molecules and suspended solid particles are used in a range of products from paints and coatings to health care and foods. The polymer molecules and the suspended particles act cooperatively to create a range of complex fluid behaviors that impact their processing. While much is known about how particles and polymers act independently to alter fluid responses, little is known about their coupled effects. This project will develop theories to predict 1) the stretching and alignment of polymer molecules by the disturbance to the flow caused by the particles, 2) how elongated solid particles or fibers align in the presence of polymers, and 3) the flow response of mixtures of particles and polymers. The influence of flow rate, flow history, and flow geometry on the behavior of polymer-particle mixtures will be examined. As part of this research, a graduate student and several undergraduates will receive training in fluid dynamics and theoretical and numerical methods. Both the principal investigator and the graduate student will participate in mentoring an undergraduate student from a group that is underrepresented in STEM fields.The interplay of particle and polymer stresses will be explored in steady shear, oscillatory shear, and extensional rheology of suspensions of spheres and fibers in polymer solutions. The hydrodynamic disturbance of the particles can dramatically alter the polymer conformation in the surrounding fluid while the polymer stress can lead to unexpected changes in the particle stresslet. The rheology of fiber suspensions is strongly influenced by the orientations of the fibers. While previous theoretical studies have suggested that polymer stresses induce fiber alignment with the vorticity axis of a steady simple shear flow, experiments reveal a greater diversity of orientations even at low particle concentrations. A search will be made for stable fixed orientations of fibers in simple shear flow and the dependence of the orientations on the rheological properties of the fluid. The rheology of dilute particle-filled polymeric liquids will be determined using an ensemble averaged equation approach. To facilitate quasi-analytic results, perturbation analyses based on small polymer concentration will be performed. In contrast to previous studies that considered second-order fluids, this approach allows an exploration of the strain rate (or Deborah number) dependence of the rheology even while considering weak polymeric stresses. Fully nonlinear computations using a finite volume method in a body-fitted coordinate system will complement the theoretical studies of fiber orientation in simple shear flow. A variety of rheological models that include and exclude shear thinning and finite extensibility will be used to understand the effect that different polymer rheological properties have on particle-polymer interactions. To broaden the diversity of future graduate students in the field, the PI and graduate student on the project will provide on-going mentorship throughout the undergraduate career of a prospective female or URM student from another university as well as offering undergraduate research projects on complex fluids.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

聚合物分子和悬浮固体颗粒的溶液用于从油漆和涂料到医疗保健和食物的一系列产品中。聚合物分子和悬浮颗粒合作起作用，以创建一系列影响其加工的复杂流体行为。尽管颗粒和聚合物如何独立地改变流体反应，但对它们的耦合效应知之甚少。该项目将发展理论以预测1）通过颗粒引起的流动的干扰，2）在聚合物存在下如何对齐聚合物分子的拉伸和对齐。颗粒和聚合物。将检查流速，流量病史和流程几何形状对聚合物粒子混合物行为的影响。作为这项研究的一部分，研究生和几名大学生将接受流体动力学以及理论和数值方法的培训。首席研究员和研究生都将参与指导一个在STEM领域中代表不足的小组的本科生。粒子和聚合物应力的相互作用将在稳定的剪切，振动性剪切和球体和球体悬架的悬浮液中进行探索聚合物溶液中的纤维。颗粒的流体动力障碍可以极大地改变周围流体中的聚合物构象，而聚合物应力会导致颗粒应力的意外变化。纤维悬浮液的流变学受到纤维方向的强烈影响。虽然先前的理论研究表明，聚合物应力诱导纤维比对，并具有稳定的简单剪切流的涡度轴，但实验甚至在低粒子浓度下也显示出更大的方向。将在简单的剪切流中搜索纤维的稳定固定方向，以及方向对流体流变特性的依赖性。稀释颗粒聚合物液体的流变学将使用合奏平均方程方法确定。为了促进准分析结果，将进行基于小聚合物浓度的扰动分析。与以前考虑二阶流体的研究相反，这种方法允许探索流变学的应变率（或Deborah数），即使在考虑弱聚合物应力的同时。使用人体拟合坐标系中使用有限体积方法的完全非线性计算将补充简单剪切流中纤维方向的理论研究。包括和排除剪切变薄和有限的可扩展性在内的多种流变学模型将用于了解不同聚合物流变学特性对粒子聚合物相互作用的影响。为了扩大该领域的未来研究生的多样性，该项目的PI和研究生将在另一所大学的潜在女或URM学生的本科职业中提供持续的指导，并为复杂流体提供本科生研究项目该奖项反映了NSF的法定任务，并通过使用基金会的智力优点和更广泛的影响审查标准来评估值得支持。