UV–thermal-cured cycloaliphatic epoxy resin (CAE) has received great attention due to high curing efficiency, low energy consumption and wide application. However, this rigid polymer with a highly crosslinked network tends to exhibit substantial brittleness. Herein, a novel toughening agent was successfully prepared by modifying nanocrystalline cellulose with Ca²⁺ (NCC-Ca). The chemical structure of NCC-Ca was characterized using Fourier transform infrared and X-ray photoelectron spectroscopies. Mechanical properties, moisture absorption and thermal properties of UV–thermal-cured NCC/CAE and NCC-Ca/CAE composites were comprehensively evaluated. With a NCC-Ca content of 0.7 wt%, the impact strength of NCC-Ca/CAE composites was maximized at 5.96 kJ m⁻², while the flexural strength of NCC-Ca/CAE composites with 0.5 wt% of NCC-Ca was maximized at 52.02 MPa. Along with the improvement in mechanical properties, NCC-Ca can also increase the glass transition temperature of CAE composites. Moreover, the toughening mechanism of the NCC-Ca/CAE composites is also discussed. © 2021 Society of Industrial Chemistry.

中文翻译：

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通过Ca2+改性纳米晶纤维素增强机械性能的UV-热固化脂环族环氧树脂复合材料

UV-热固化脂环族环氧树脂（CAE）由于固化效率高、能耗低、应用广泛而受到广泛关注。然而，这种具有高度交联网络的刚性聚合物往往表现出明显的脆性。在此，通过用Ca ²⁺ (NCC-Ca)改性纳米晶纤维素成功制备了一种新型增韧剂。NCC-Ca 的化学结构使用傅里叶变换红外和 X 射线光电子光谱进行表征。综合评估了紫外热固化 NCC/CAE 和 NCC-Ca/CAE 复合材料的机械性能、吸湿性和热性能。NCC-Ca 含量为 0.7 wt% 时，NCC-Ca/CAE 复合材料的冲击强度最大为 5.96 kJ m ^-2，而含有 0.5 wt% NCC-Ca 的 NCC-Ca/CAE 复合材料的弯曲强度最大为 52.02 MPa。随着力学性能的提高，NCC-Ca还可以提高CAE复合材料的玻璃化转变温度。此外，还讨论了 NCC-Ca/CAE 复合材料的增韧机制。© 2021 工业化学学会。