Wangchang Li,Wei Huang,Yue Kang,Yu Gong,Yao Ying,Jing Yu,Jingwu Zheng,Liang Qiao,Shenglei Che
Modified cyanate resins (G-CE) and functionalized silica fibers (K-SFs) were obtained by introducing glycidyl polyhedral oligomeric silsesquioxane (G-POSS) and γ -aminopropyltriethoxy silane coupling agent (KH-550), respectively. G-CE and K-SFs were then used to fabricate K-SFs/G-CE wave-transparent composites. The activation energy of the G-CE blends decreased to 49.80 kJ/mol, which led to a decrease in the curing temperature from 274 °C to 254 °C. The contact angle of the functionalized silica fibers increased considerably to 107.4°; this modified the interfacial compatibility, which enhanced the mechanical properties . The K-SFs/G-CE composite had a maximum flexural strength of 548.1 MPa and flexural modulus of 19.3 GPa, which were increases of 86.7% and 48.5% compared to the corresponding values of SFs/CE composite (flexural strength of 293.5 MPa and flexural modulus of 13.0 GPa). In addition, the ε and tan δ of the K-SFs/G-CE composite decreased to 2.63 and 3.3 × 10 −3 , respectively, which were respective decreases of 6.5% and 23.0% compared with the corresponding values of SFs/CE composite ( ε of 2.76 and tan δ of 4.6 × 10 −3 ). Hence, the resulting K-SFs/G-CE composites are good candidate materials for high performance wave-transparent composites.
The improvement in energy storage performance of graphene/polymer composites has long been restricted by insufficient breakdown strength (Eb) and high dielectric loss, both of which result from conductive losses caused by the aggregation of graphene nanosheets. In this paper, aminopropylisobutyl polyhedral oligomeric silsesquioxane (POSS-NH2) encapsulated graphene oxide (GO) (GO-g-POSS) hybrids were prepared to inhibit the restacking of graphene and block the formation of conductive paths. Furthermore, the design of sandwich-structured films is also an efficient approach to improving the breakdown performance of composite materials. Novel sandwich-structured composite films containing outer layers of BNNS/PVDF films and a middle rGO-g-POSS/PVDF layer were successfully prepared by the layer-by-layer assembly process. The B-0.50-B sandwich-structured composites achieved an optimal discharge energy storage density (Ue) of 9.08 J cm−3 and Eb of 432 MV m−1.
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