Due to the increase in the amount of produced epoxy resin waste, it is desirable to recycle this material to reduce the burden on the environment. Despite many studies focusing on recovering fibers from composites, few studies have focused on recycling the resin itself. In this study, we developed a new approach for recycling the decomposed amine-cured epoxy resin as an amine curing agent. Following the decomposition of the epoxy resin in nitric acid, a nitrated and decomposed resin product was extracted from the nitric acid solution. The resulting extract was then hydrogenated to convert the nitro group into amino group, and the hydrogenated extract was incorporated into the epoxy resin by replacing a portion of the original curing agent. The obtained recycled resin exhibited a higher tensile strength and comparable tensile modulus compared to the virgin resin due to the presence of aromatic amino groups. Moreover, when 20 mass% of the curing agent was replaced with the hydrogenated extract, the recycled resin with the optimized formulation exhibited tensile strength comparable to that of the virgin one. This approach demonstrates a novel recycling method for creating a closed loop of amine-cured epoxy resins.

中文翻译：

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使用硝酸回收环氧树脂的新方法：通过氢化再生分解产物

由于产生的环氧树脂废物量增加，希望回收这种材料以减少对环境的负担。尽管有许多研究侧重于从复合材料中回收纤维，但很少有研究侧重于回收树脂本身。在这项研究中，我们开发了一种将分解的胺固化环氧树脂作为胺固化剂回收利用的新方法。环氧树脂在硝酸中分解后，从硝酸溶液中提取硝化和分解的树脂产物。然后将所得提取物氢化以将硝基转化为氨基，并通过替换一部分原始固化剂将氢化提取物掺入环氧树脂中。由于芳族氨基的存在，与原始树脂相比，所获得的再生树脂表现出更高的拉伸强度和相当的拉伸模量。此外，当 20 质量％的固化剂被氢化提取物代替时，具有优化配方的再生树脂表现出与原始树脂相当的拉伸强度。这种方法展示了一种新的回收方法，用于创建胺固化环氧树脂的闭环。