Sliding of adhesive nanoscale polymer contacts
Sliding of adhesive nanoscale polymer contacts
复制标题
DOI：
10.1016/j.jmps.2020.103931
复制
发表时间：
2020-07
影响因子：
5.3
通讯作者：
D. Das;I. Chasiotis
中科院分区：
文献类型：
--
作者：
D. Das;I. Chasiotis
摩擦和粘附之间的相互作用是天然和合成软材料的宏观行为的决定因素。在这项工作中，纳米级聚合物纤维之间的接触的界面法向和剪切粘合强度进行了研究，使用新的实验辅助微机械装置，通过该装置，实时测量直径在400 nm - 4 µm范围内的单个聚丙烯腈（PAN）纳米纤维之间的临界法向和切向拉脱力。使用Johnson-Kendall-Roberts（JKR）和Maugis-Dugdale（M-D）弹性粘合剂接触模型计算的正常分离下的粘合功与纤维直径无关，与本体PAN的表面能的两倍相当。在剪切剥离下，使用JKR和M-D模型结合线弹性断裂力学（LEFM）计算接触区域的剥离。M-D模型结合LEFM可以预测实验获得的切向拉脱力不稳定性。的界面剪切粘附强度被证明是恒定的接触半径（25-140 nm）的宽范围内，约等于材料的剪切应力屈服。因此，剪切屈服被证明是在与强货车德瓦尔斯粘附相互作用的单个聚合物纳米纤维的剪切分离期间的控制机制。
The interaction between friction and adhesion is a defining factor of the macroscopic behavior of natural and synthetic soft materials. In this work, the interfacial normal and shear adhesion strength of contacts between nanoscale polymeric fibers were studied using novel experiments aided by micromachined devices by which the critical normal and tangential pull-off forces between individual polyacrylonitrile (PAN) nanofibers with diameters in the range 400 nm – 4 µm were measured in real-time. The work of adhesion under normal detachment, as computed using the Johnson-Kendall-Roberts (JKR) and the Maugis-Dugdale (M-D) models for elastic adhesive contact, was shown to be independent of the nanofiber diameter and comparable to twice the surface energy of bulk PAN. Under shear detachment, peeling of the contact area was calculated using the JKR and the M-D models combined with linear elastic fracture mechanics (LEFM). The M-D model combined with LEFM could predict the experimentally obtained tangential pull-off force instabilities. The interfacial shear adhesion strength is shown to be constant for a broad range of contact radii (25–140 nm) and approximately equal to the material shear stress at yielding. Thus, shear yielding is shown to be the controlling mechanism during shear detachment of individual polymer nanofibers interacting with strong van der Waals adhesion.