SGER: Flow-induced anisotropic thermal energy transport in elongational flows of polymer liquids

SGER：聚合物液体拉伸流动中流动引起的各向异性热能传输

• 批准号: 0837907
• 负责人: David Venerus
• 金额: --
• 依托单位: Illinois Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-01 至 2010-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0837907&HistoricalAwards=false
• 关键词: SGER; Flow; induced; anisotropic; thermal

CBET-0837907VenerusAn experimental study of flow-induced anisotropic thermal conduction in polymer melts subjected to elongational deformations is proposed. In previous studies, we have developed and applied a novel optical technique to obtain quantitative measurements of the thermal conductivity tensor in shear flows of poly-isobutylene melts. Results from these previous studies are consistent with the stress-thermal rule, which says the stress and thermal conductivity tensors are linearly related. In the present study, the same optical technique is applied to polymer melts in simple elongational flows. Time-dependent measurements of two components of thermal conductivity tensor (parallel and perpendicular to the stretch direction) will be obtained as functions of strain and strain rate. In addition, mechanical (stress) and optical (birefringence) data are obtained in the same flows. The thermal conductivity and stress data are used to examine for the first time the validity of the stress-thermal rule in elongational flows of polymer melts, and the validity of the stress-thermal rule for polymers having different chemistries. Experimental results from the present and previous studies are used to develop a molecular-level understanding of flow-induced anisotropic thermal conduction in polymers.Flows of polymeric melts in fabrication processes such as fiber spinning and injection molding are inherently non-isothermal. Consequently, the efficient design and operation of these processes relies on a good understanding of thermal transport in flowing polymer melts. Despite this well-accepted importance, heat transfer in deforming polymer liquids, and in particular, flow-induced anisotropic thermal conduction, is poorly understood. Accurate computer-aided design of polymer processes requires a model for estimating the thermal conductivity as a function of deformation or stress. The experimental results obtained in this study directly address this need. Results from this investigation will also be invaluable in the development of predictive, or semi-predictive, theories for flow-induced anisotropic thermal conduction in polymers.This project is jointly funded by the Thermal Transport Processes (TTP) Program and the Fluid Dynamics (FD) Program, both of the Chemical, Bioengineering, Environmental, and Transport Systems (CBET) Division within the Directorate for Engineering (ENG).

CBET-0837907Venerus 提出了聚合物熔体在拉伸变形下流动引起的各向异性热传导的实验研究。 在之前的研究中，我们开发并应用了一种新颖的光学技术来定量测量聚异丁烯熔体剪切流中的导热率张量。 先前这些研究的结果与应力-热规则一致，即应力和热导率张量呈线性相关。 在本研究中，相同的光学技术应用于简单拉伸流动中的聚合物熔体。 将获得热导率张量的两个分量（平行于和垂直于拉伸方向）的随时间变化的测量结果，作为应变和应变率的函数。 此外，还可以在同一流程中获得机械（应力）和光学（双折射）数据。 导热率和应力数据首次用于检验聚合物熔体拉伸流动中应力-热规则的有效性，以及具有不同化学性质的聚合物的应力-热规则的有效性。 目前和之前研究的实验结果用于在分子水平上理解聚合物中流动引起的各向异性热传导。纤维纺丝和注射成型等制造过程中聚合物熔体的流动本质上是非等温的。 因此，这些过程的有效设计和操作依赖于对流动聚合物熔体中热传输的良好理解。 尽管其重要性已被广泛接受，但人们对变形聚合物液体中的传热，特别是流动引起的各向异性热传导知之甚少。 聚合物工艺的精确计算机辅助设计需要一个模型来估计热导率作为变形或应力的函数。 本研究获得的实验结果直接解决了这一需求。 这项研究的结果对于聚合物中流动引起的各向异性热传导的预测或半预测理论的发展也将具有无价的价值。该项目由工程理事会 (ENG) 化学、生物工程、环境和运输系统 (CBET) 部门的热传输过程 (TTP) 计划和流体动力学 (FD) 计划联合资助。