Du Jianyi, Páez Javier, Otero Pablo, Sánchez Pablo B
Hatsopoulos Microfluids Laboratory, Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, United States.
Department of Chemical Engineering, University of Vigo, Vigo 36210, Spain.
Carbohydr Polym. 2023 Nov 15;320:121229. doi: 10.1016/j.carbpol.2023.121229. Epub 2023 Jul 24.
It is critical to monitor the structural evolution of complex fluids for optimal manufacturing performance, including textile spinning. However, in situ measurements in a textile-spinning process suffer from the paucity of non-destructive instruments and interpretations of the measured data. In this work, kinetic and rheo-optic properties of a cellulose/ionic liquid solution are measured simultaneously while fibers are regenerated in aqueous media from a model wet-spinning process via a customized polarized microscope. This system enables to capture key geometrical and structural information of the fiber under spinning at varying draw ratios and residence time, including the flow kinematics extracted from feature tracking, and the flow-induced morphology and birefringent responses. A physics-oriented rheological model is applied to connect the kinematic and structural measurements in a wet-spinning process incorporating both shear and extensional flows. The birefringent responses of fibers under coagulation are compared with an orientation factor incorporated in the constitutive model, from which a superposed structure-optic relationship under varying spinning conditions is identified. Such structural characterizations inferred from the flow dynamics of spinning dopes exhibit strong connections with the mechanical properties of the fully-regenerated fibers, thus enabling to predict the spinning performance in a non-destructive protocol.
为了实现最佳制造性能（包括纺织纺丝），监测复杂流体的结构演变至关重要。然而，纺织纺丝过程中的原位测量受到非破坏性仪器的匮乏以及测量数据解释的困扰。在这项工作中，通过定制的偏振显微镜，在模型湿法纺丝过程中，当纤维素/离子液体溶液在水介质中再生纤维时，同时测量其动力学和流变光学性质。该系统能够在不同拉伸比和停留时间下捕获纺丝过程中纤维的关键几何和结构信息，包括从特征跟踪中提取的流动运动学，以及流动诱导的形态和双折射响应。应用一个面向物理的流变模型来连接湿法纺丝过程中包含剪切流和拉伸流的运动学和结构测量。将凝固过程中纤维的双折射响应与本构模型中包含的取向因子进行比较，从中确定不同纺丝条件下叠加的结构 - 光学关系。从纺丝原液的流动动力学推断出的这种结构表征与完全再生纤维的机械性能表现出紧密联系，从而能够以非破坏性方式预测纺丝性能。
