Acquisition of Controlled Strain Rheometers

该拨款用于购置一台流变学科学熔体伸长流变仪（RME）和一台流变学科学先进流变膨胀系统（ARES）。这两种仪器都需要用于研究散装液体和近固体表面的复杂流体动力学。RME是唯一可用于研究聚合物熔体拉伸流动行为的商用流变仪，而ARES流变仪是唯一可以同时测量聚合物液体中随时间变化的剪应力和正应力的研究级商用仪器。所提出的仪器将是德州农工大学的首个此类仪器，并将用于四个研究项目和两个研究生水平的聚合物工程课程的课堂演示。在一个项目（DMR-9816105）中，RME和ARES流变仪将用于确定支链聚合物及其与化学性质相同的线性聚合物共混物的应变硬化和表观延伸增稠行为的基本来源。本研究将由主要研究者和合作者合成一系列新颖的An-A- an和An-A(a)m-An多臂聚丁二烯来促进。从理论上讲，这些聚合物被认为抓住了商业上重要的支链聚烯烃的本质，并将为聚合物结构对拉伸和剪切流动中的松弛动力学和流变行为的影响提供新的思路。在另一个研究项目（CMS-9713372）中，ARES流变仪将用于完善由首席研究员和他的学生最近开发的一种新的叠加阶/稳定剪切流技术，用于隔离剪切流中聚合物轮廓长度拉伸的动力学。在第三个项目（CTS-9624254）中，将使用两步接枝程序将聚合物和低分子量氯硅烷依次接枝到ARES流变仪平台上。然后，表面改性流变仪平台将用于块状、化学性质相同的聚合物的标准剪切流变测试，以研究聚合物在表面附近的动量传递、摩擦阻力、壁滑移和弛豫动力学。这项研究的结果将为首席研究员和他的学生开发的用于量化固体表面附近聚合物摩擦、滑移和动力学的缩放理论提供第一次严格的测试。这笔拨款用于购买一台流变学科学熔体伸长流变仪（RME）和一台流变学科学先进流变膨胀系统（ARES）。这两种仪器都需要用于研究散装液体和固体表面附近的聚合物性质。RME是唯一可用于研究聚合物熔体拉伸流动特性的商用流变仪，而ARES流变仪是唯一允许测量聚合物液体中多种应力组分的研究级商用仪器。所提出的仪器将是德州农工大学的首个此类仪器，并将用于四个研究项目和两个研究生水平的聚合物工程课程的课堂演示。四个项目中有三个是美国国家科学基金会资助的活动，涉及塑料材料和聚合物表面涂层的结构-加工关系的发展。高分子工程课程向学生介绍高分子物理和高分子流变学。

0079278ArcherThis grant provides for the acquisition of a Rheometrics Scientific Melt ElongationalRheometer (RME) and a Rheometrics Scientific Advanced RheologicalExpansion System (ARES). Both instruments are needed for investigating complexFluid dynamics in bulk liquids and near solid surfaces. The RME is the onlycommercial rheometer available for studying extensional flow behavior of polymer melts, while the ARES rheometer is the only research-grade commercial instrument that allows simultaneous, time-dependent measurements of shear and normal stresses in polymer liquids. The proposed instruments will be the first of their kind at Texas A&M University, and will be used in four research projects and for class room demonstrations in two graduate-level polymer engineering courses. In one project (DMR-9816105), the RME and ARES rheometers will be used to determine the fundamental origin of strain hardening and apparent extension thickening behavior of branched polymers and their blends with chemically identical linear polymers. This research will be facilitated by a series of novel An-A-An and An-A(A)m-An multi-arm polybutadienes synthesized by the principal Investigator and a collaborator. These polymers are believed, on theoretical grounds, to capture the essence of commercially important branched polyolefins and will shed new light on the effect of polymer architecture on relaxation dynamics and rheological behavior in extensional and shearing flows. In another research project (CMS-9713372), the ARES rheometer will be used to perfect a new superimposed step/steady shear flow technique recently developed by the principal investigator and his students for isolating dynamics of polymer contour length stretch in shear flows. In the third project (CTS-9624254), a two-step grafting procedure will be used to sequentially graft polymers and low molecular weight chlorosilanes to the ARES rheometer platens. The surface modified rheometer platens will then be used in standard shear rheological testing of bulk, chemically identical polymers to investigate momentum transport, frictional drag, wall slip, and relaxation dynamics of polymers near surfaces. Results from this study will provide the first rigorous test of a scaling theory developed by the principal investigator and his students for quantifying polymer friction, slip, and dynamics near solid surfaces.%%%This grant provides for the purchase of a Rheometrics Scientific Melt ElongationalRheometer (RME) and a Rheometrics Scientific Advanced RheologicalExpansion System (ARES). Both instruments are needed for investigating polymerproperties in bulk liquids and near solid surfaces. The RME is the onlycommercial rheometer available for studying extensional flow properties ofpolymer melts, while the ARES rheometer is the only research-grade commercial instrument that allows measurements of multiple components of stress in polymer liquids. The proposed instruments will be the first of their kind at Texas A&M University, and will be used in four research projects and for class room demonstrations in two graduate-level polymer engineering courses. Three of the four projects are National Science Foundation sponsored activities related to development of structure-processing relationships in plastic materials and for polymer surface coatings. The polymer engineering courses introduce students to polymer physics and polymer rheology.