The cooperative effect of short-cut carbon fiber and carbon black on the performance of electric-driven morphing skins

Abstract

Shape memory polymers (SMPs) with variable stiffness properties become the most promising candidate materials for morphing skins. Due to the influence of external environment, electric-driven composite skin is becoming the trend of development. In this paper, rubber toughed hydro-epoxy morphing skins filled with conductive carbon black (CB) and short-cut carbon fiber (SCF) were prepared. The total mass fraction of CB and SCF was fixed at 2.6 wt %. By adjusting the content ratio of CB and SCF (CB/SCF), the in-plane mechanical property, fracture morphology, thermal-mechanical behavior, electronic resistivity, and out-of-plane shape memory behavior of five types of skin were investigated. These results showed that the addition of CB and SCF had a synergistic effect on skin performance. When CB/SCF was 5:5, the composite skin had the highest tensile strength and the lowest glass transition temperature (Tg). In the thermo-active shape memory test, the composite skin presented good shape fixity rate (Rf) and shape recovery rate (Rr). Due to the bridging effect of SCFs on CB particles, the composite skin with CB/SCF ratio of 5:5 has the minimum resistivity and can return to its initial shape within 29 s at 60 V.

Low-Shrinkage and Degradable UV Imprint Lithography Based on Biomass-Derived Epoxidized Soybean Oil and Cardanol

“…To reduce the shrinkage rate of UV-curing systems, a cationic curing reaction of epoxy resin is favored by more and more researchers. − Compared with free-radical systems, a ring-opening reaction of epoxy resin has more natural advantages than a chain reaction of double bonds to single bonds. − Meanwhile, a cationic ring-opening reaction is insensitive to oxygen, and the active center of the reaction exists for a long period, which is conducive to the postcuring process. − Xia et al prepared cationic UV curable composites with high impact strength using trarysulfonium hexafluorophosphate salt as a photoinitiator and hyperbranched polyester terminated with six hydroxy groups and linear hydroxy-ended polytetramethylene ether glycol as toughness modifiers . Nonetheless, a single cationic curing system shows a slow reaction rate and low curing efficiency, and the absorption wavelength of the photoinitiator is concentrated at 250 nm, which requires irradiation by a high-pressure mercury lamp.…”