Modelling the jetting of dilute polymer solutions in drop-on-demand inkjet printing
Modelling the jetting of dilute polymer solutions in drop-on-demand inkjet printing
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DOI：
10.1016/j.jnnfm.2013.05.007
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发表时间：
2013-11-01
影响因子：
3.1
通讯作者：
Morrison, N. F.
中科院分区：
文献类型：
--
作者：
Mcllroy, C.;Harlen, O. G.;Morrison, N. F.
我们已经开发了一个简化的喷射模型，该模型预测了按需喷墨打印（DoD）中稀释的单分散聚合物溶液的可打印性。聚合物分子被建模为可伸缩的非线性弹性（FENE）哑铃与流体参数选择，以适应Zimm模型。三个不同的喷射制度的预测，定义的韦森伯格数Wi和分子的可扩展性L。射流的行为取决于限制射流速度的关键因素;状态1受流体粘度限制，状态2受弹性限制，状态3受高应变拉伸粘度限制。我们研究了两种聚合物溶液不同的粘度在不同的喷射条件下（即打印速度和喷嘴的几何形状），并比较我们的结果与实验数据和轴对称模拟。发现可以以所需速度喷射的最大聚合物浓度与分子量NI成比例，并且取决于溶剂品质因数V。我们发现聚合物可以在特定喷嘴几何形状的打印头中伸展，这对可以喷射的最大聚合物浓度具有相当大的影响。此外，这种“预拉伸”机制可以使喷嘴中的分子完全延伸，因此，由于喷嘴出口处的高应变率，分子可以经历中心断裂。(c)2013作者Elsevier B. V.出版，保留所有权利。
We have developed a simplified jetting model that predicts the printability of dilute, monodisperse polymer solutions in drop-on-demand (DoD) inkjet printing. Polymer molecules are modelled as finitely extensible non-linear elastic (FENE) dumbbells with fluid parameters chosen to fit the Zimm model. Three distinct jetting regimes are predicted, defined by the Weissenberg number Wi and the extensibility L of the molecules. The behaviour of the jet depends upon a critical factor that limits jet speed; regime 1 is restricted by fluid viscosity, regime 2 by elasticity and regime 3 by high strain extensional viscosity. We study two polymer solutions of disparate viscosity under different jetting conditions (i.e. print speed and nozzle geometry) and compare our results with experimental data and axisymmetric simulations. The maximum polymer concentration that can be jetted at a desired speed is found to scale with molecular weight NI, and is dependent on the solvent quality factor v. We find that polymers can be stretched out in the print head for particular nozzle geometries, which has a considerable effect on the maximum polymer concentration that can be ejected. Furthermore, this 'pre-stretch' mechanism can fully extend molecules in the nozzle and consequently, molecules can undergo central scission due to high strain rates at the nozzle exit. (c) 2013 The Authors. Published by Elsevier B.V. All rights reserved.