Precision Microprofile Extrusion with a Wall Slip Condition

该奖项的研究目标是开发和研究一种新的精密微型材挤出工艺，该工艺的基础是使用场诱导材料传输机制在微挤出物上创建共形流体层。为了形成薄的共形流体层，将与少量可混溶的低相对分子质量或低聚添加剂混合的聚合物通过长模槽挤出，从而产生增强的相分离。这种剪切诱导的相分离反过来会导致低分子流体迁移到模具表面，从而形成共形流体层，并为聚合物挤出物创造壁滑条件。由于壁面滑移，流动应力最小，从而减小了口模膨胀量。此外，由于流体层与聚合物挤出物固有的可混性，极大地减少或消除了表面张力效应。主要的研究活动将是：1)论证这种新型微型材挤压工艺的技术可行性；2)对微型材挤压中场诱导相分离有一个基本的认识；3)建立这一新工艺的预测模型。这项研究的成功复杂化将为精密微型材挤出提供一种新的制造工艺。精密的微轮廓提供独特的功能(例如，增强的表面活性、衍射效应、波传输效率等)。这是他们的循环同行无法实现的。虽然精密的微型材在新兴的生化、生物医学和电信行业中非常受欢迎，但制造它们的有效工艺尚未开发出来。因此，新工艺将填补技术空白，并为各种应用创造新的市场部门。此外，在增强场诱导相迁移方面获得的知识将特别有助于开发其他创新工艺，可能是在涂层、润滑和选择性表面改性领域。

The research objective of this award is to develop and investigate a novel precision microprofile extrusion process, the basis of which uses a field-induced material transport mechanism for creating a conformal fluidic layer on the microextrudate. To create a thin conformal fluidic layer, a polymer blended with a small amount of miscible low-molecular-weight or oligomeric additive is extruded through a long die channel, causing enhanced phase separation to occur. This shear-induced phase separation, in turn, causes the low-molecular-weight fluid to migrate to the die surface, thus forming a conformal fluidic layer and creating a wall-slip condition for the polymer extrudate. Due to wall slip, the flow stresses and thus the amount of die swell are minimized. Furthermore, due to the inherent miscibility of the fluidic layer with the polymer extrudate the surface tension effect is greatly reduced or eliminated. The main research activities will be 1) to demonstrate the technical feasibility of this novel microprofile extrusion process, 2) to gain a fundamental understanding of field-induced phase separation in microprofile extrusion and, 3) to formulate a predicative model for this new process. Successful complication of this research will lead to a novel manufacturing process for precision microprofile extrusion. Precision microprofiles offer unique functions (e.g., enhanced surface activities, diffractive effects, wave transmission efficiency, etc.) that cannot be realized by their circular counterparts. Although precision microprofiles are highly desirable in the emerging biochemical, biomedical and telecommunication industries, a capable process for fabricating them is yet to be developed. The new process would therefore fill a technical gap and create new market sectors for a wide variety of applications. Moreover, the knowledge gained on the enhancement of field-induced phase migration would be particularly useful in the development of other innovative processes, potentially in the areas of coating, lubrication, and selective surface modification.