Use Particle-Tracking Velocimetric Observations to Guide Evidence-Based Investigations of PolymerDynamics in Presence of Chain Entanglement

技术摘要：拟议的研究旨在实现三个目标：(A)仔细检查以前的结果，以确定技术错误和科学歧义的潜在来源；(B)消除实验上的困难，以验证在没有任何在文献中引起争议的人工制品的情况下，新出现的画面是否仍然成立；(C)在新认识的基础上，进一步探讨链缠结网因外部变形而崩解的性质。具体来说，目前的许多发现尚未得到确凿的证明，除非进行改进的实验，否则无法形成聚合物流变学的新的现象学基础。这些实验包括(i)在剪切细胞边缘的样品不会发生断裂的情况下，对应变引起的链解缠结的研究；（ii）在没有任何夹杂物的情况下，流动双折射测量，例如被de Gennes怀疑为剪切带源的固体颗粒。单分子成像测速是一种有效的方法，可以探测无外来粒子纠缠体系中的速度场，并直接确定剪切不均匀性是由流动诱导的聚合物迁移还是由不均匀链解纠缠引起的。最后，为了预测聚合物加工的潜在影响，粒子跟踪测速技术将应用于研究压力驱动流动和相关现象中链解缠的影响。非技术概要：在这个国家，每年有超过2000亿磅的塑料和橡胶材料被制成消费品。如此巨大的体积通常以类似于倒蜂蜜或挤牙膏的方式流动。不同的聚合物材料在不同的加工条件下如何流动是一个具有学术和经济重要性的课题。拟议研究的成果可能会改变我们长期以来对聚合物流动的认识，并改变现有教科书中有关该主题的内容。目前的科学发现和拟议的研究提供了新的希望，最终可能使国内市场在全球竞争和创新中处于领先地位，以更有效地生产更高质量的石油消费品。最终，拟议工作的结果可能直接影响塑料和橡胶工业的研发方向。这项调查的影响显然超越了美国的边界，因为新出现的画面开始在课堂上讨论，并在互联网http://eres.avs.uakron.edu/eres/coursepass.aspx?cid=647上录制视频流。该研究的可视化密集性质也使其成为初中和高中青少年的有吸引力的材料，使科学直观，观察和直接感知。

TECHNICAL SUMMARYThe proposed research aims to achieve three objectives: (A) carefully examining the previous results to identify potential sources of technical error and scientific ambiguity; (B) removing experimental difficulties to verify whether the new emerging picture would still hold in absence of any artifacts that have caused controversies in the literature; (C) building on the newly available understanding to further probe the nature of disintegration of chain entanglement network due to external deformation. Specifically, many current findings have not been proved to beyond doubt and cannot form the new phenomenological foundation for polymer rheology unless improved experiments are carried out. These experiments include (i) interrogation of strain-induced chain disentanglement under circumstances where the sample at the edge of a shear cell would not suffer fracture and (ii) flow birefringence measurements in absence of any inclusions such as solid particles that have been suspected by de Gennes to be the source of shear banding. Single-molecule imaging velocimetry is proposed as an effective method to probe velocity field in entangled systems without any foreign particles and to directly determine whether shear inhomogeneity would arise from flow-induced polymer migration or from non-uniform chain disentanglement. Finally, in anticipation of potential implications for polymer processing, particle-tracking velocimetric technique will be applied to examine effect of chain disentanglement in pressure-driven flow and related phenomena.NON-TECHNICAL SUMMARY:Each year, more than two hundred billion pounds of plastic and rubber materials are made into consumer products in this country. Such a huge volume typically flows in a manner similar to pouring honey or squeezing tooth paste. How the various polymeric materials flow under different processing conditions is a subject of both academic and economic importance. The fruits of the proposed studies could alter our long-held knowledge about polymer flow and transform the contents of existing textbooks on the subject. Current scientific findings and proposed research offer new hope that could eventually give the domestic market a cutting edge in the global competition and innovation for more efficient production of petroleum-based consumer goods of higher quality. Ultimately, the outcome of the proposed work could directly impact the R&D directions in the plastic and rubber industries. The impact of this investigation is clearly going beyond the border of the United State, as the emerging new picture begins to be discussed in classroom and recorded for video streaming on the world wide web at http://eres.avs.uakron.edu/eres/coursepass.aspx?cid=647. The visualization-intensive nature of the research also makes it attractive materials for youngsters in middle and high schools, making science intuitive, observational and straightforward to perceive.