Additive-Free and Support-Free 3D Printing of Thermosetting Polymers with Isotropic Mechanical Properties,ACS Applied Materials & Interfaces

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Additive-Free and Support-Free 3D Printing of Thermosetting Polymers with Isotropic Mechanical Properties
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2021-01-21 , DOI: 10.1021/acsami.0c19608
Mohammadreza Mahmoudi ₁ , Scott R. Burlison ₁ , Salvador Moreno ₁ , Majid Minary-Jolandan ₁

Affiliation

The democratization of thermoplastic 3D printing is rooted in the ease of processing enabled by economical melting and shaping. Thermosetting polymers, on the other hand, have not enjoyed this advantage given that thermosetting resins cannot hold their shape without cross-linking or excessive fillers, and once cross-linked, they cannot be extruded for printing. Due to this formidable challenge, thus far, 3D printing of thermosetting polymers has been limited to the photopolymerization of specialized photosensitive resins or extrusion of resins loaded with large fractions (as high as 20 wt %) of rheology modifiers. Here, we report a rheology-modifier- and photoinitiator-free process for the 3D printing of a pure commercial epoxy polymer, without any resin modification and using a conventional 3D printer. A low-cost non-Newtonian support material that switches between solid–fluid states under a nozzle shear stress enables the printing of complex 3D structures and the subsequent and ″one-step″ curing. Our results show that the one-step curing eliminates the often-compromised interlayer adhesion common in layer-by-layer 3D printing processes and results in unprecedented isotropic mechanical properties (strength, elastic modulus, tensile toughness, and strain to failure). This in-bath print and cure (IBPC) 3D printing process for thermosetting polymers is low-cost, scalable, high-speed (nozzle speeds exceeding 720 cm/min), and high-resolution (down to 220 μm filament size). We demonstrate potential applications for hobbyists, structural and aerospace components, and fiber-reinforced composites, among others.

中文翻译：

具有各向同性机械特性的热固性聚合物的无添加剂和无支撑3D打印

热塑性3D打印的民主化源于经济融化和成型所带来的易于加工。另一方面，由于热固性树脂在没有交联或没有过多的填料的情况下不能保持其形状，并且一旦交联就不能挤出用于印刷，则热固性聚合物没有享受到这一优点。到目前为止，由于这一艰巨的挑战，热固性聚合物的3D打印仅限于专用光敏树脂的光聚合或负载有大比例（高达20 wt％）流变改性剂的树脂的挤出。在这里，我们报告了一种纯流态改性剂和无光引发剂的工艺，用于纯商业环氧聚合物的3D打印，无需任何树脂改性，并使用常规3D打印机。一种低成本的非牛顿支撑材料，可在喷嘴剪切应力下在固液状态之间切换，从而可以打印复杂的3D结构以及随后的“一步式”固化。我们的结果表明，一步固化消除了在逐层3D打印过程中常见的经常受到损害的层间附着力，并导致了空前的各向同性机械性能（强度，弹性模量，拉伸韧性和断裂应变）。这种用于热固性聚合物的浴内打印和固化（IBPC）3D打印工艺具有低成本，可扩展，高速（喷嘴速度超过720 cm / min）和高分辨率（最小至220μm长丝尺寸）的优点。我们展示了业余爱好者，结构和航空航天组件以及纤维增强复合材料等的潜在应用。

更新日期：2021-02-03

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