Can Nanoscale Inclusions Effectively Reduce the Viscosity and Modulus of Polymer Melts?

纳米级夹杂物能否有效降低聚合物熔体的粘度和模量？

• 批准号: 0400840
• 负责人: Michael Mackay
• 金额: $ 26.28万
• 依托单位: Michigan State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-05-01 至 2007-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0400840&HistoricalAwards=false
• 关键词: Nanoscale; Inclusions; Effectively; Reduce; Viscosity

Proposal Title: Can Nanoscale Inclusions Effectively Reduce the Viscosity and Modulus of Polymer Melts?Proposal Number: CTS-0400840Principal Investigator: Michael E. MackayInstitution: Michigan State UniversityIn this project, the flow and physical properties of a suspension or slurry is being investigated. However, the particles are smaller than the fluids molecules in which they are dispersed and this produces unusual effects. We have found that nanoparticles with a size of order 5-10 nm suspended in a polymeric liquid with molecules of size 15-40 nm produce a liquid that has a viscosity lower than the neat polymeric liquid itself. A viscosity reduction is at odds with Einsteins century old prediction that Brownian particles increase the viscosity of liquids. Indeed all observations suggest that a viscosity increase is always present in particulate suspensions. A recent publication on this effect is in press in the journal Nature Materials. Since the particles are so small it is believed they influence the dynamics of the polymeric liquid on a local scale. The nanoparticles apparently increase the free volume in the polymeric liquid as well as confine the polymer molecules to produce the viscosity decrease. Further, contemporary methods to quantify entanglements suggest no change in the entanglement density. It is the purpose of this work to further elucidate the phenomenon and resolve this quandary. A recent discovery, included in the preliminary results, is that very chemically different nanoparticle (polyethylene). polymer (polystyrene) systems can be molecularly dispersed as long as the particle is smaller than the polymer. The polyethylene. polystyrene system is a model phase separating system and it has been discovered that changing the molecular topology of one component into a particle-like conformation affects its solubility and stability in a polymeric liquid. This is a unique result, not fully understood at present and represents one aspect of the proposed research. This could create a new class of molecular alloys. Further research will be conducted with fullerenes, as a model system whose size is much smaller than available nanoparticles, and single wall carbon nanotubes, as a model system to introduce a new particulate geometry. These systems will be utilized to generalize the viscosity reduction effect. We will use a variety of techniques in the proposed work to measure the dispersion of the nanoparticles as well the state of the suspending fluids. chain-like molecules. These techniques include: rheological characterization, thermal analysis, mechanical testing, electron optics evaluation and small angle neutron scattering. All this instrumentation exists in the group, is on campus or is available at Argonne National Laboratory. Graduate and undergraduate students in the research group will be exposed to these results and in some cases will gather results together as we have done when performing neutron scattering. There are three females and three males in the research group and through teamwork participation of an underrepresented group will broaden their learning experience. Dissemination of these results will be presented through the scientific literature and conferences as well as through undergraduate and graduate level lectures. The principal investigator sets aside one lecture every semester in the introductory (sophomore) course he teaches to introduce his research to the students. This lecture is well received and gives students an introduction to the research process as well as the results of research. The proposed research is unique and is at odds to contemporary observations. Inclusion of this topic in the research lecture will demonstrate how science and engineering is continuously evolving and not stagnant. Many underrepresented students attend this lecture and immediately after, as well as for many months thereafter, they show interest in research and wish to undertake research with the principal investigator or other professors.

提案标题：纳米级夹杂物能否有效降低聚合物熔体的粘度和模量？提案编号：CTS-0400840 首席研究员：Michael E. Mackay 机构：密歇根州立大学 在该项目中，正在研究悬浮液或浆料的流动和物理性质。然而，这些颗粒比它们分散在其中的流体分子小，这会产生不寻常的效果。我们发现，尺寸为 5-10 nm 的纳米粒子悬浮在分子尺寸为 15-40 nm 的聚合物液体中，产生的液体粘度低于纯聚合物液体本身。粘度降低与爱因斯坦百年前的预测相矛盾，即布朗粒子会增加液体的粘度。事实上，所有观察结果都表明，颗粒悬浮液中始终存在粘度增加。最近关于这种效应的出版物发表在《自然材料》杂志上。由于颗粒非常小，因此相信它们会在局部范围内影响聚合物液体的动力学。纳米颗粒明显增加了聚合物液体中的自由体积并限制了聚合物分子以产生粘度降低。此外，当代量化纠缠的方法表明纠缠密度没有变化。这项工作的目的是进一步阐明这一现象并解决这一困境。初步结果中包含的最新发现是化学性质非常不同的纳米颗粒（聚乙烯）。只要颗粒小于聚合物，聚合物（聚苯乙烯）体系就可以分子分散。聚乙烯。聚苯乙烯体系是一种模型相分离体系，已发现将一种组分的分子拓扑改变为颗粒状构象会影响其在聚合物液体中的溶解度和稳定性。这是一个独特的结果，目前尚未完全理解，代表了拟议研究的一个方面。这可能会创造出一种新型的分子合金。进一步的研究将以富勒烯作为模型系统进行，其尺寸比现有纳米颗粒小得多，并以单壁碳纳米管作为模型系统来引入新的颗粒几何形状。这些系统将用于推广粘度降低效果。我们将在拟议的工作中使用各种技术来测量纳米粒子的分散以及悬浮流体的状态。链状分子。这些技术包括：流变表征、热分析、机械测试、电子光学评估和小角度中子散射。所有这些仪器都存在于该小组、校园内或阿贡国家实验室。研究小组中的研究生和本科生将接触到这些结果，并且在某些情况下会将结果收集在一起，就像我们在进行中子散射时所做的那样。研究小组中有三名女性和三名男性，通过团队合作，代表性不足的群体的参与将拓宽他们的学习经验。这些成果将通过科学文献和会议以及本科生和研究生水平的讲座来传播。首席研究员每学期在他教授的入门（大二）课程中留出一次讲座，向学生介绍他的研究。这次讲座受到了热烈的欢迎，并向学生介绍了研究过程以及研究结果。拟议的研究是独特的，并且与当代的观察结果不一致。将此主题纳入研究讲座将展示科学和工程如何不断发展而不是停滞不前。许多代表性不足的学生参加了这次讲座，在讲座结束后以及之后的几个月里，他们表现出了对研究的兴趣，并希望与首席研究员或其他教授一起进行研究。