In this study, the effect of the post-curing process as well as the long-term weathering behavior were studied for three different three-dimensional printable, pigmented (black), nonstabilized, ultraviolet (UV) cure resin formulations (A and B being thiol–ene chemistry, and C being acrylate chemistry). To study the effect of the post-cure process, the printed parts were post-cured using one of five different processes: no post-cure, UV-only, heat-only, UV+heat, and electron beam (EB) post-curing. Bulk tensile properties and nanohardness were measured for each of the systems and post-cure conditions. For weathering studies, the parts were post-cured using the recommended UV-only process and exposed using the ASTM D7869 exterior weathering protocol. The results show that the post-cure process had a significant effect on the final mechanical properties of the resins and was dependent on the underlying resin chemistry. Thermal post-curing was not as effective as UV curing for Resin C compared with the two other resins, which could both undergo thermal polymerization. In addition, Resin B showed the smallest change in mechanical properties before and after post-curing, regardless of the type of post-curing process. EB post-curing, even at very low dosages, that is, from 0.05 to 1 Mrad, resulted in considerable post-cure cross-linking to the point of embrittlement and a significant drop in percent elongation at break for dosages above 0.5 Mrad. Although Resins A and C outperformed Resin B in photooxidation performance, all three resins demonstrated that promising results considering no hindered amine light stabilizers were used in the formulations.

中文翻译：

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汽车应用增材制造：还原光聚合材料的机械和耐候性

在这项研究中，研究了三种不同的三维可印刷、着色（黑色）、不稳定、紫外线 (UV) 固化树脂配方（A 和 B 为硫醇-烯化学，C 是丙烯酸酯化学）。为研究后固化工艺的效果，使用五种不同工艺之一对打印部件进行后固化：无后固化、仅紫外线、仅加热、紫外线+加热和电子束 (EB) 后固化养护。对每个系统和后固化条件测量整体拉伸性能和纳米硬度。对于风化研究，部件使用推荐的仅紫外线工艺进行后固化，并使用 ASTM D7869 外部风化协议进行曝光。结果表明，后固化过程对树脂的最终机械性能有显着影响，并且取决于底层树脂的化学性质。与其他两种树脂相比，树脂 C 的热后固化不如 UV 固化有效，这两种树脂都可以进行热聚合。此外，无论后固化过程的类型如何，树脂 B 在后固化前后的机械性能变化最小。EB 后固化，即使在非常低的剂量下，即从 0.05 到 1 Mrad，也会导致相当大的固化后交联到脆化点，并且对于高于 0.5 Mrad 的剂量，断裂伸长率会显着下降。尽管树脂 A 和 C 的光氧化性能优于树脂 B，