Novel Applications of Viscoplastic Fluids: Creating New Products for the Pulp and Paper Sector

该方案研究了一种新的平台技术，即流体动力聚焦与反应多流体分层相结合，用于三维打印中空水凝胶管。这项技术类似于蜘蛛丝的生产，我们的目标是创造一种环保的体外电路用聚氯乙烯管材的替代品。我们迫切的科学需要是将这些管子的断裂能增加大约5倍，我们建议通过使用微米或纳米纤维增强，即木纤维的积木来实现这一点。文献综述表明，少量添加这些增强材料可以显著提高材料的断裂韧性。关键的是，我们要解决的问题是了解增强纤维的取向分布与最终用途机械性能之间的关系。 我们的方法将把计算和实验结合起来。我们将使用服从稳态福克-普朗克关系的概率密度函数来估计取向分布。这种方法是基于纤维取向概率分布函数的矩张量，关键是依赖于精确的闭合近似，该闭合近似将通过使用x射线微计算机断层扫描的实验进行校准。在实验上，我们将开发一种进气歧管来控制增强纤维在水凝胶管中的定向分布，并在我们的实验室设备上进行演示。 这项工作的影响将是双重的。科学地了解分散纤维相在不同流动条件下的宏观和微观物理特性是流体力学和过程工程领域向前迈出的重要一步。在数值方面，对纤维之间相互作用以及与背景流相互作用的高保真模拟在纤维尺度上仍然很少见。在工程方面，如果这个过程被证明是可行的，并行化立即就可以用于工业生产。这将允许利用木纤维原料制造长丝、管子或薄膜，以用于未来高性能生物复合材料的生产以及纺织生产。一个为期五年的项目将由一名博士后研究员、两名博士生和五名化学或机械工程专业的本科生助理进行。

This proposal investigates a novel platform technology, i.e. hydrodynamic focusing coupled with reactive multi-fluid layering, to 3D print hollow hydrogel tubes. This technology is similar to the production of a spider's silk and our goal is to create an eco-friendly alternative to PVC tubing for extracorporeal circuits. Our immediate scientific need is to increase the fracture energy of these tubes by about 5-fold and we propose to do so by reinforcement with micro- or nano-fibrillated cellulose, i.e. building blocks of wood fibres. Literature reviews indicate that the fracture toughness increases dramatically by small additions of these reinforcing materials. Critically, the question we address is understanding of the relationship between orientation distribution of the reinforcement fibre to the end-use mechanical properties. Our approach will blend computation and experimentation. We will estimate the orientation distribution using a probability density function that obeys a steady-state Fokker-Planck relationship. This approach is based on moment tensors of the fibre orientation probability distribution function, and crucially rely on accurate closure approximations that will be calibrated through experiment using x-ray micro-computed tomography. Experimentally, we will develop an inlet manifold to control orientationdistribution of the reinforcing fibres in the hydrogel tubing and demonstrate this on our lab-scale device. The impact of the work will be two-fold. Scientifically, gaining insight into the macroscale and microscale physics of a dispersed fibrous phase under different flow conditions are significant steps forward in the fields of fluid mechanics and process engineering. On the numerical front, high-fidelity simulations of the interactions of the fibres with each other and with the background flow, that occur at the scale of fibres, are still rare in the literature. On the engineering side, if this process is shown to be feasible, parallelization is immediately available for industrial production. This will allow manufacturing of filaments, tubes or films from wood fibre raw material for future production of high-performance bio-composites as well as for textile production. A five-year project is proposed to be conducted by one post-doctoral fellow, two PhD students and 5 undergraduate assistants in either Chemical or Mechanical Engineering.