Nanomaterials with their extremely high free surfaces can effectively augment damping in nanocomposites via frictional sliding along the interface of nanomaterials and a matrix. Despite this potential, existing state of knowledge about the damping behavior of graphene reinforced nanocomposites is at an embryonic stage. In particular, it is not clear how various morphological parameters of graphene contribute to damping. We aim to reveal the mechanical damping behavior of graphene-reinforced polymer nanocomposites as a function of the surface morphology of graphene nanoplatelets through combined experiments and continuum modeling. The vibrational damping behavior of graphene nanocomposites was studied via dynamic mechanical analysis via cycling tension-compression tests. Two graphene types, “single-layer graphene” (SLG) and “graphene nanoplatelets” (GNP), with different aspect ratios in polystyrene (PS) matrix were used. We developed a micromechanical model which relates damping in nanocomposites to filler-matrix frictional sliding. The experimental work demonstrated that the addition of GNP will increase the damping properties of the nanocomposites by up to ~70%. The model predictions for PS-GNP were in good agreement with experimental data. However, contrary to the model predictions, the damping coefficient of nanocomposites with lower aspect ratio particles (PS-SLG) was lower than PS-GNP. Further experimental studies showed that the surface roughness of the SLG (owed to their small thickness) has a negative effect on damping properties as they delay interfacial debonding and frictional sliding. Flat (less rough) graphene triggers intrinsic friction mechanism earlier and may be more beneficial to enhance damping. Surface undulation of the nanoparticles, which can happen for atomically thin particles, will delay damping.

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石墨烯尺寸和形态：对聚合物纳米复合材料阻尼性能的特殊影响

具有极高自由表面的纳米材料可以通过沿纳米材料和基体界面的摩擦滑动有效地增加纳米复合材料的阻尼。尽管有这种潜力，关于石墨烯增强纳米复合材料的阻尼行为的现有知识仍处于萌芽阶段。特别是，目前尚不清楚石墨烯的各种形态参数如何对阻尼做出贡献。我们的目标是通过组合实验和连续介质建模，揭示石墨烯增强聚合物纳米复合材料的机械阻尼行为作为石墨烯纳米片表面形态的函数。石墨烯纳米复合材料的振动阻尼行为通过循环拉伸-压缩试验的动态力学分析进行了研究。两种石墨烯类型，使用了在聚苯乙烯 (PS) 基质中具有不同纵横比的“单层石墨烯”(SLG) 和“石墨烯纳米片”(GNP)。我们开发了一种将纳米复合材料中的阻尼与填料-基质摩擦滑动联系起来的微机械模型。实验工作表明，添加 GNP 将使纳米复合材料的阻尼性能提高约 70%。PS-GNP 的模型预测与实验数据非常吻合。然而，与模型预测相反，具有较低纵横比颗粒 (PS-SLG) 的纳米复合材料的阻尼系数低于 PS-GNP。进一步的实验研究表明，SLG 的表面粗糙度（由于它们的厚度小）对阻尼性能有负面影响，因为它们延迟了界面脱粘和摩擦滑动。平坦（不那么粗糙）的石墨烯更早地触发内在摩擦机制，可能更有利于增强阻尼。纳米颗粒的表面起伏（这可能发生在原子级细颗粒上）将延迟阻尼。