Enhancing mechanical properties and thermal conductivity in polymer bonded explosives by multi-scale surface modification of carbon fibers

Poor interfacial interaction and strength largely restrict the overall performance and practical application of carbon fibers (CFs) reinforced composites. The favorable interfacial properties were the key to realize superior mechanical properties in composites. Herein, we reported a novel multi-scale surface modification strategy of CFs to strengthen interfacial properties. Based on chemical oxidation treatment, the surface of CFs was further in situ grafted by a crosslinked high-strength polymer network consisting of aromatic diisocyanate, graphene oxide (GO) and polyethylenen glycol (PEG), which significantly improved the interfacial bonding and mechanical strength of interface layer itself. Benefitting from this multi-scale surface treatment, a high-efficiency mechanical enhancement of polymer bonded explosives (PBX) was achieved. With only 0.3 wt% fiber content, the maximum tensile and compressive strength PBX composites were both significantly improved, which were 63 % and 39 % higher than those of pure PBX, respectively. Meanwhile, the thermal conductivity was also enhanced, yielding a significant synergistic enhancement effect. The interface failure mechanism of the composite under stress was clarified by the fracture morphology characterization. This study sheds a light for exploring novel surface modification and has the potential application in in high performance polymer composites.