STTR Phase I: Precision Polymer Microprofile Extrusion with a Conformal Fluidic Control Environment

小企业技术转让研究（STTR）第一阶段项目将使用挤出机出口处的鞘液控制微挤出聚合物（微型材）的形状。 微型材被定义为具有非圆形横截面的连续长丝，其具有精确的微特征，并且平均直径为100微米或更小。在标准聚合物挤出工艺中，在挤出物的自由表面处的边界条件在聚合物离开模具之后不受控制。 因此，挤出物在挤出胀大和表面张力的联合作用下的自由变形导致挤出型材的显著形状变形。 在所提出的技术中，使用具有与聚合物挤出物的表面张力紧密匹配的表面张力的低粘度流体，将有助于抑制由不同机理引起的横截面的形状变化。 所提出的技术将提供一种有效的方法来生产精密聚合物微尺寸型材，用于包括医疗领域在内的各种应用。 例如，这些微轮廓可以用作人工肾脏和人工毛细血管静脉网络中的功能细丝。 在聚合物复合材料工业中还需要具有高度非圆形横截面的长丝，以通过与聚合物基体的机械互锁来改善复合材料的完整性。

The Small Business Technology Transfer Research (STTR) Phase I project will control the shape of microextruded polymers (microprofiles) using a sheath fluid at the exit of the extruder. Microprofiles are defined as continuous filaments having a non-circular cross-section with precision microfeatures and a mean diameter of 100 microns or less. In the standard polymer extrusion process, the boundary condition at the free surface of the extrudate is not controlled after the polymer exits the die. Consequently, the free deformation of the extrudate subjected to the combined effects of die swell and surface tension contributes to significant shape distortion of the extruded profile. In the proposed technology, the use of a low-viscosity fluid with closely matched surface tension as that of the polymer extrudate, will help suppress the shape change of the cross-section caused by different mechanisms. The proposed technology will provide an efficient method to produce precision polymeric micro-size profiles for various applications including the medical field. For example, these microprofiles can be used as functional filaments in artificial kidneys and artificial capillary vein networks. Filaments with highly non-circular cross-sections are also needed in the polymer composites industry to improve the integrity of the composite via mechanical interlocking with the polymer matrix.