直接挤出成型用环氧树脂的流变性及其可打印性

直接挤出成型制造适用于任何含或不含添加剂的膏状或凝胶状复合材料,对复合材料制造技术具有深远意义。通过探讨热固性环氧树脂的流变学行为与挤出成型特性,得出热固性环氧树脂在直接挤出成型制造应用中的通用性流变学参数。通过向复合材料中加入增稠剂,对其流变学行为进行设计。结果表明:在高剪切速率(50 s~(-1))和低剪切速率(0.01 s~(-1))下,添加30%纳米黏土的环氧树脂的流变学行为较适合挤出式3D打印工艺。利用龙门式气动挤出式3D打印机,对复合材料的打印成型质量进行试验分析和验证。结合试验结果探讨了喷头高度对复合材料成型质量的影响,并且提出适用于喷头高度临界值的计算方法。探讨了挤出率、剪切速率等因素对成型质量的作用规律。针对多层打印问题,提出包含补偿系数的多层打印的临界喷头高度的计算方法。以上研究对促进基于复合材料的挤出式3D打印具有积极意义。

Rheological property and printability of epoxy resin materials for direct extrusion fabrication

Using composite materials to replace aluminum alloy, steel or titanium alloy is of far-reaching significance. With the development of new material science, the advantages of direct extrusion fabrication are becoming increasingly prominent. In principle, direct extrusion fabrication is suitable for any paste or gel composite material with or without additives. The purpose of this study is to find out the general rheological parameters of thermosetting epoxy resin in the direct extrusion fabrication application by discussing the rheological properties and extrusion fabrication properties of the composite. The rheological behavior of the composite was designed by adding thickener. A gantry pneumatic extrusion 3D printer was designed and built to test and analyze the printing effect of composite materials. Combined with the experimental results, the influence of nozzle height on printing results was analyzed, and a calculation method suitable for critical value of nozzle height was proposed. The effects of shear rate, extrusion rate and extrusion pressure on the molding quality of materials were also analyzed. Aiming at the problem of multi-layer printing, a method for calculating the critical value of nozzle height of multi-layer printing was proposed. The above conclusions provide guidance methods for the extrusion 3D printing of composite materials.