In order to solve the problem of poor interfacial adhesion between aramid fibers and a rubber matrix, an efficient and mild modification method was proposed via polydopamine and mercapto functionalized graphene oxide (GO) and carbon nanotube (CNTs) hybrids synergistically modifying aramid fibers. GO and CNTs were firstly stacked and assembled into unique 3D GO-CNTs hybrids through π-π conjugation. Then, the mercapto functionalization of the assembled 3D GO-CNTs hybrids was realized via the dehydration condensation reaction between the hydroxyls of GO and the silanol groups of coupling agent. Finally, the mercapto functionalized 3D GO-CNTs hybrids were grafted onto the aramid fibers, which were pre-modified by polydopamine through the Michael addition reaction mechanism. The surface morphology and chemical structures of GO-CNTs hybrids and fibers and the interfacial adhesion strength between fibers and rubber matrix were investigated. The results showed that the modification method had brought about great changes in the surface structure of fibers but not generated any damage traces. More importantly, this modification method could improve the interfacial strength by 110.95%, and the reason was not only the reactivity of functional groups but also that the 3D GO-CNTs hybrids with excellent mechanical properties could effectively share interfacial stress. The method proposed in this paper was universal and had the potential to be applied to other high-performance fiber-reinforced composites.
To improve interfacial adhesion to rubber matrix, a lower cost surface modification strategy of ultrahigh molecular weight polyethylene (UHMWPE) fiber was proposed by replacing expensive dopamine with the two‐component system of catechol/tetraethylenepentamine (CAT/TEPA) and then depositing nano zinc oxide (ZnO NPs). By Michael addition reaction or Schiff base reaction between CAT and TEPA, the CAT/TEPA layer was coated on the fiber surface, and further served as a secondary functional platform to realize ZnO NPs deposition through coordination. The surface morphology, chemical structure and composition, wettability and thermal property of the UHMWPE fibers were investigated to evaluate the process and effect of the surface modification. The results of the single‐filament tensile test indicated that the tensile strength of the UHMWPE fibers has no deterioration after the modification treatment. In comparison with the original fiber, the pull‐out test showed that the highest interface adhesion between the modified UHMWPE fibers and rubber matrix increased by 80.4%. Additionally, it was found that the appropriate zinc ion concentration played an important role in the modification effect.
The current work focuses on the effect of explosive ratio R on the comprehensive properties of Ti/Al clads manufactured via explosive welding. The lower and upper limits of explosive ratio, namely R1 and R2, were determined according to the R–δf (flyer plate thickness) welding window. Two TA2/1060 explosive cladding plates were successfully manufactured at the different explosive ratios. Microstructure investigation was conducted by optical microscopy (OM), scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS). The small wave bonding interface was observed at R1, where the vortex structure containing the ingot structure appeared periodically. The bonding interface presented a big wave bonding morphology and a locally continuous melting layer at R2. Many prolonged grains and adiabatic shear bands (ASBs) were found near the interface for a greater explosive load. Intermetallic compounds were formed in the bonding zones of the two plates. The thickness of element diffusion area increased with an increasing explosive ratio. Comparative tests of mechanical properties indicated that the tensile shear strength at R1 was higher. The microhardness, tensile strength, and bending performance of the two plates are similar and acceptable. Tensile fracture analysis indicated the fracture mode at R1 was ductile fracture, while the explosive cladding plate at R2 had mainly ductile fracture with quasi-cleavage fracture as the supplement.
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