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

该提案研究了一种新的平台技术，即流体动力学聚焦与反应性多流体分层相结合，以3D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生态友好的替代品，以替代PVC管用于体外循环。我们迫切的科学需求是将这些管的断裂能增加约5倍，我们建议通过用微米或纳米原纤化纤维素（即木纤维的构建块）增强来实现这一点。文献综述表明，通过少量添加这些增强材料，断裂韧性显著增加。关键是，我们解决的问题是理解增强纤维的取向分布与最终用途机械性能之间的关系。 我们的方法将融合计算和实验。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，并且关键地依赖于将通过使用X射线微计算机断层扫描的实验来校准的精确闭合近似。在实验上，我们将开发一个入口歧管来控制水凝胶管中增强纤维的取向分布，并在我们的实验室规模的设备上演示。 这项工作的影响将是双重的。在不同的流动条件下，深入了解分散纤维相的宏观和微观物理学是流体力学和过程工程领域的重要进步。在数值方面，高保真模拟的纤维相互之间的相互作用，并与背景流，发生在纤维的规模，仍然是罕见的文献。在工程方面，如果这个过程被证明是可行的，并行化可以立即用于工业生产。这将允许用木纤维原料制造长丝、管材或薄膜，用于未来高性能生物复合材料的生产以及纺织品生产。 本项目拟由一名博士后、两名博士生和5名本科生助理在化学或机械工程领域进行，为期五年。

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.