Collaborative printing and in-situ frontal curing of highly-viscous thermosetting composites
Collaborative printing and in-situ frontal curing of highly-viscous thermosetting composites
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DOI：
10.1016/j.jmapro.2023.01.048
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发表时间：
2023-01-26
影响因子：
6.2
通讯作者：
Wang, Shiren
中科院分区：
文献类型：
--
作者：
Gao, Chongjie;Liu, Ruochen;Wang, Shiren
通过正面聚合快速制造热固性材料对于热固性复合材料非常有吸引力，因为它可以在有限的能源消耗下实现预期的脱碳和制造灵活性；然而，由于3D打印工艺的流变性要求以及通常用于降低油墨粘度的正面固化树脂油墨在高温下的适用期有限，高粘度热固性复合材料（例如，室温下>100,000 mPa.s）的3D打印和正面固化具有挑战性。我们报告了一种基于材料的原位组合 3D 打印工艺，用于高粘度热固性材料的打印和原位正面固化。具体来说，在打印过程中超声波雾化器喷射固化剂溶液，以实现与树脂低聚物在微米级水平的原位混合。多物理场模拟显示了厚度方向上的固化度分布，并根据挤出沉积速率、沉积层厚度和超声波喷雾器振幅提供了打印窗口。进一步进行实验发现，随着超声振幅的增大，锋面速度增大，而锋面温度几乎保持不变。固化程度和固化均匀性随着超声波振幅的增加而提高，但随着印刷层厚度的增加而降低。打印了不同超声波振幅和挤出层厚度的样品，并测试了其力学性能。酚醛环氧树脂的拉伸强度和杨氏模量分别达到47.56 MPa和2.19 GPa。论证了该方法复合印刷的可行性。当短纤维含量为 5 wt% 时，打印复合材料的拉伸强度和杨氏模量分别达到 66.71 MPa 和 3.65 GPa。该方法提供了一种快速、节能的方法来制造高粘度热固性材料及其复合材料。
Rapid manufacturing of thermosets via frontal polymerization is very attractive for thermosetting composites due to the expected decarbonization and manufacturing flexibility with limited energy consumption; however, it is challenging for 3D printing and frontal curing of highly-viscous thermoset composites (e.g., >100,000 mPa.s at room temperature) because of the rheology requirement of the 3D printing process and limited pot life of frontal curable resin inks under elevated temperature, which is usually used to reduce the viscosity of inks. We report an in-situ combining materials-based 3D printing process for printing and in-situ frontal curing of highly viscous thermosets. Specifically, an ultrasonic atomizer sprays the curing agent solution during the printing process to achieve an in-situ mixing with the resin oligomers at a microscale level. Multiphysics simulation indicated the curing degree distribution through the thickness direction and a printing window is provided depending on the extrusion deposition rate, the deposition layer thickness, and the ultrasonic sprayer amplitude. Further experi-ments were carried out, and it was found that the frontal velocity increased, and the frontal temperature remained almost unchanged with the rise of the ultrasonic amplitude. The curing degree and curing uniformity were improved with the increase of the ultrasonic amplitude but decreased with the increase of the printing layer thickness. Samples with different ultrasonic amplitudes and extrusion layer thicknesses were printed, and their mechanical properties were tested. The tensile strength and Young's modulus of novolac epoxy resin reached 47.56 MPa and 2.19 GPa, respectively. The feasibility of this method for composite printing was demonstrated. At a 5 wt% loading of short fibers, the tensile strength and Young's modulus of as-printed composites reached 66.71 MPa and 3.65 GPa. This method provides a fast and energy-efficient way to manufacture highly viscous thermosets and their composites.