Collaborative Research: Dynamics of Ionomer Melts

合作研究：离聚物熔体动力学

• 批准号: 1066517
• 负责人: Robert Weiss
• 金额: $ 21.97万
• 依托单位: University of Akron
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2015-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1066517&HistoricalAwards=false
• 关键词: Collaborative; Research; Dynamics; Ionomer; Melts

1066517Weiss Ionomers are chain molecules with strong attractive intermolecular forces that exhibit complex flow phenomena due to strong physical associations of the ionic dipoles attached to the chains. The strength of the interactions and the relaxation times of the associations are dependent on the nature of the fixed ion and the mobile counterion, the concentration of such charges and the time, temperature and amplitude of the deformation of the fluid. The details of the relationship between the physical intermolecular associations and the melt flow of ionomers is poorly understood, and this has hampered, in many cases, their commercial application. Previous research on the rheology of ionomers has been hindered by the inability to separate effects from the dipolar interactions and chain entanglements. This research focuses on characterizing the rheological behavior of a model ionomer system, lightly sulfonated polystyrene ionomers, with molecular weight below that where chain entanglements occur. The unsulfonated polystyrene is a Rouse chain, and only the influence of the dipolar interactions will affect the rheological properties of the ionomer melts. The specific objectives of the research are: 1) to develop an understanding of how the nature of the mobile counterion affects the rheology, specifically the relaxation times of the chain and the ionic associations; 2) to determine how elasticity is developed in these unentangled systems, 3) to resolve the origin of shear-thickening that has been observed in ionomer melts, and 4) to understand how low molecular weight additives can be used to engineer the melt rheology. The project will include the synthesis and characterization of the ionomers, steady state, dynamic shear and relaxation measurements of tionomer melts, and real-time, small angle neutron scattering evaluation of the ionomer chain structure in the melt during shear deformation. Graduate students will be trained in the field of complex fluids and polymer rheology, skills that are increasingly in demand by the U.S. polymer industry. High school, undergraduate and graduate students will participate in the research. The PI is part of a demonstration program between the University of Akron and a local high school in the city of Akron, OH, that provides opportunities for students, grades 10-12 to carry out inquiry-based research in the PI's laboratory. Graduate and undergraduate students will be recruited from academic programs and by targeted recruiting of students from underrepresented groups. The PI and students working on this research will also cooperate with the Akron Global Polymer Academy to develop teaching and demonstration aids on complex fluids. Ionomers are used in a variety of commercial applications, including commodity thermoplastics, thermoplastic elastomers, membranes (e.g., for fuel cells, reverse osmosis, humidification and batteries), compatibilizers for polymer blends, adhesives, hydrocarbon solution viscosifiers, drilling muds and organogels. An understanding of the rheological behavior of ionomers and how to control the rheology by composition, external variables such as temperature and stress, and with additives is important with regard to those applications, as well as for processing films and shaped articles from these polymers. A detailed understanding of how to engineer the processing behavior of ionomer melts while still achieving the desirable physical and mechanical properties of these materials could result in new technologies, such as the extrusion of functional thin films and roll-to-roll processing, technologies that are currently dominated by solution casting and batch processes.

1066517WEISS离子体是具有强大吸引人分子的链分子，由于连接到链条的离子偶极子的牢固物理相关性，它们表现出复杂的流动现象。相互作用的强度和关联的松弛时间取决于固定离子和移动抗衡离子的性质，这种电荷的浓度以及流体变形的时间，温度和幅度。对物理分子间关联与离聚体的熔体流之间的关系的细节知之甚少，在许多情况下，这受到了阻碍它们的商业应用。无法将偶性相互作用和链纠缠的效应分开，因此阻碍了有关离聚体流变学的先前研究。这项研究的重点是表征模型电离系统的流变行为，即略微磺化的聚苯乙烯离子体，分子量低于发生链纠缠的分子量。未悬而未决的聚苯乙烯是一个隆起的链，只有偶极相互作用的影响才会影响离子体熔体的流变特性。研究的具体目的是：1）对移动柜台的性质如何影响流变学，特别是链条和离子关联的放松时代； 2）确定在这些未进入系统中如何开发弹性，3）解决在离子体熔体中观察到的剪切厚的起源，以及4），以了解如何使用低分子量添加剂来设计熔体流变性。该项目将包括离子体的合成和表征，稳态，动态剪切和弛豫测量值，以及在剪切变形过程中熔体中电离链结构的实时，小角度中子散射评估。研究生将在复杂的流体和聚合物流变学领域接受培训，这些技能越来越多地受到美国聚合物行业的需求。高中，本科生和研究生将参加这项研究。 PI是阿克伦大学和俄亥俄州阿克伦市的当地高中之间的演示计划的一部分，为学生提供了10 - 12年级的机会，以在PI实验室进行基于查询的研究。研究生和本科生将从学术课程中招募，并有针对性地招募来自代表性不足的小组的学生。 PI和从事这项研究的学生还将与Akron全球聚合物学院合作，开发有关复杂液体的教学和演示辅助工具。离子体用于各种商业应用，包括商品热塑性，热塑性弹性体，膜（例如，用于燃料电池，反渗透，加湿和电池），聚合物混合物，粘合剂，辅助碳溶液溶液溶液粘度，液压粘合剂，钻探泥浆和细胞泥浆和细胞泥浆和细胞泥和细胞层的兼容器。了解离子体的流变行为，以及如何通过组成，温度和压力等外部变量以及添加剂来控制流变，对于这些应用以及这些聚合物的加工膜和形状的物品很重要。对如何设计电离材料熔体的处理行为的详细理解，同时仍能达到这些材料的理想物理和机械性能，可能会导致新技术，例如功能性薄膜的挤出和滚动到滚动处理，当前由解决方案铸造和批量铸造过程主导的技术。