This paper introduces a green approach for preparing well-dispersed graphene nanoplates (GNPs) in vinyl-ester (VE) resin. The GNPs were exfoliated in a novel binary-solvent system comprised of a water and ethanol mixture (S nanocomposites). Water and ethanol were considered poor solvents for graphene, but a combination of them could be an ideal solvent mixture. TEM images of the S nanocomposites revealed well-exfoliated graphene sheets with a few wrinkles. Hence, the effective surface areas of the GNPs considerably increased, playing a vital role in enhancing the performance of the nanocomposites. With the incorporation of just 0.4 wt% of exfoliated GNPs (S2 nanocomposite) in the VE, the tensile strength, and toughness enhanced by 51%, and 63%, respectively. Fractography analysis indicated smooth fracture surfaces of pure resin changed to very rough surface structures for the S2 nanocomposite. The viscoelastic properties of the specimens indicated that directly loading GNPs into the resin decreased the glass transition temperature (Tg) of the VE resin. In contrast, the samples prepared by liquid-phase exfoliation enhanced the Tg of the VE. Lastly, the barrier properties of the S2 nanocomposite revealed that its water absorption decreased by 26% compared to the pure resin.

中文翻译：

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基于二元溶剂系统的乙烯基酯纳米复合材料可良好剥离石墨烯并增强性能

本文介绍了一种在乙烯基酯（VE）树脂中制备分散良好的石墨烯纳米片（GNP）的绿色方法。GNP 在由水和乙醇混合物（S 纳米复合材料）组成的新型二元溶剂系统中剥离。水和乙醇被认为是石墨烯的不良溶剂，但它们的组合可能是理想的溶剂混合物。S 纳米复合材料的 TEM 图像显示出剥离良好的石墨烯片，并带有一些皱纹。因此，GNPs的有效表面积大大增加，对提高纳米复合材料的性能发挥着至关重要的作用。通过在 VE 中加入 0.4 wt% 的剥离 GNP（S2 纳米复合材料），拉伸强度和韧性分别提高了 51% 和 63%。断口分析表明，S2 纳米复合材料的纯树脂的光滑断裂表面变成了非常粗糙的表面结构。样品的粘弹性表明，直接将 GNP 负载到树脂中会降低 VE 树脂的玻璃化转变温度 (Tg)。相反，通过液相剥离制备的样品提高了VE的Tg。最后，S2纳米复合材料的阻隔性能表明，与纯树脂相比，其吸水率降低了26%。