Viscoelastic and thixotropic characterization of paraffin/photopolymer composites for extrusion-based printing
Viscoelastic and thixotropic characterization of paraffin/photopolymer composites for extrusion-based printing
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DOI：
10.1063/5.0104157
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发表时间：
2022-09-01
影响因子：
4.6
通讯作者：
Benjamin, Chandler C.
中科院分区：
文献类型：
--
作者：
Cipriani, Ciera E.;Shu, Yalan;Benjamin, Chandler C.
功能材料的三维打印（3DP）对于需要具有复杂或定制几何形状的物体或具有不同属性的梯度或区域的打印的高级应用越来越重要。一种常见的3d打印技术是直接墨水书写（DIW），在这种技术中，可打印的墨水由充满固体颗粒的流体基质组成，后者可以作为流变性改性剂和功能性填料，以实现与性能相关的特性。虽然填料载荷和粘度之间的关系已经描述了许多聚合物体系，但需要对三维（3D）可打印复合材料的流变特性进行全面描述，以加快新材料的创建。在这篇手稿中，使用模型石蜡/光聚合物复合油墨，研究了填料负载和印刷能力之间的关系，其中包含0和73vol。%石蜡微珠。液体光聚合物树脂是一种牛顿流体，加入石蜡微珠可以增加油墨粘度，增强剪切减薄性能、粘弹性和触变性，这些都是通过平行板流变实验确定的。利用Einstein和Batchelor在胶体悬浮流变学方面的研究成果，建立了描述油墨触变行为的模型，与实验结果吻合较好。这些特性都有助于高填充（>= 43vol）的可打印性。%石蜡)石蜡/光聚合物复合油墨。通过这项工作，能够量化DIW油墨的理想流变特性，并有选择地控制和预测其流变性能，这将有助于开发具有可调功能的3D打印材料，从而使3D打印技术超越当前的能力。
Three-dimensional printing (3DP) of functional materials is increasingly important for advanced applications requiring objects with complex or custom geometries or prints with gradients or zones with different properties. A common 3DP technique is direct ink writing (DIW), in which printable inks are comprised of a fluid matrix filled with solid particles, the latter of which can serve a dual purpose of rheology modifiers to enable extrusion and functional fillers for performance-related properties. Although the relationship between filler loading and viscosity has been described for many polymeric systems, a thorough description of the rheological properties of three-dimensional (3D) printable composites is needed to expedite the creation of new materials. In this manuscript, the relationship between filler loading and printability is studied using model paraffin/photopolymer composite inks containing between 0 and 73vol. % paraffin microbeads. The liquid photopolymer resin is a Newtonian fluid, and incorporating paraffin microbeads increases the ink viscosity and imparts shear-thinning behavior, viscoelasticity, and thixotropy, as established by parallel plate rheometry experiments. Using Einstein and Batchelor's work on colloidal suspension rheology, models were developed to describe the thixotropic behavior of inks, having good agreement with experimental results. Each of these properties contributes to the printability of highly filled (>= 43vol. % paraffin) paraffin/photopolymer composite inks. Through this work, the ability to quantify the ideal rheological properties of a DIW ink and to selectively control and predict its rheological performance will facilitate the development of 3D printed materials with tunable functionalities, thus, advancing 3DP technology beyond current capabilities.