The epoxidized natural rubber containing 25 mol% epoxide (ENR-25) was cured through crosslinking reactions with dodecanedioic acid (DA), both with and without activation by 1,2-dimethylimidazole (DMI). Analysis of the Fourier Transform Infrared (FTIR) spectroscopy of the DMI-activated DA-cured ENR revealed new absorption peaks at 1440 cm and 1505 cm, indicating the presence of C-N stretching vibrations and carboxylate ions compared to samples without DMI activation. Additionally, ENR-graphene (GP) nanocomposites with various GP loadings were investigated, which revealed the formation of inter- and intramolecular hydrogen and covalent bonds within the ENR and GP networks. Furthermore, DMI activation of ENR cured with dicarboxylic acid accelerated the crosslinking reaction, reducing scorch and cure times while enhancing properties such as tensile strength, toughness, and 100 % modulus. Moreover, the incorporation and increased loading of GP in ENR nanocomposites synergistically enhanced strength properties, delta torque, crosslink density, initial relaxation modulus, thermal resistance, and electrical conductivity. This enhancement is attributed to interactions between the polar functional groups on GP surfaces and the functional groups of ENR adducts cured with DMI-activated dicarboxylic acid. Moreover, the ENR-GP nanocomposites exhibited a low percolation threshold concentration at 1.25 phr, enabling the formation of fully conductive GP networks within the ENR matrix. The significance of this study is to simplify the curing and production processes of ENR composites, offering promising self-healing capabilities and potential for reuse and recycling.

中文翻译：

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通过咪唑活化二羧酸固化体系交联增强环氧化天然橡胶-石墨烯纳米复合材料的性能


含有 25mol% 环氧化物的环氧化天然橡胶 (ENR-25) 通过与十二烷二酸 (DA) 的交联反应进行固化，无论是否经过 1,2-二甲基咪唑 (DMI) 活化。对 DMI 激活的 DA 固化 ENR 的傅里叶变换红外 (FTIR) 光谱分析显示，在 1440cm 和 1505cm 处有新的吸收峰，表明与没有 DMI 激活的样品相比，存在 C-N 伸缩振动和羧酸根离子。此外，还研究了具有不同 GP 负载量的 ENR-石墨烯 (GP) 纳米复合材料，揭示了 ENR 和 GP 网络内分子间和分子内氢键和共价键的形成。此外，用二羧酸固化的 ENR 的 DMI 活化加速了交联反应，减少了焦烧和固化时间，同时增强了拉伸强度、韧性和 100% 模量等性能。此外，ENR纳米复合材料中GP的加入和增加的负载量协同增强了强度性能、δ扭矩、交联密度、初始松弛模量、热阻和电导率。这种增强归因于 GP 表面上的极性官能团与用 DMI 活化的二羧酸固化的 ENR 加合物的官能团之间的相互作用。此外，ENR-GP 纳米复合材料表现出 1.25 phr 的低渗透阈值浓度，从而能够在 ENR 基质内形成完全导电的 GP 网络。这项研究的意义在于简化 ENR 复合材料的固化和生产过程，提供有前途的自修复能力以及再利用和回收的潜力。