To meet the energy demand for flexible and miniaturized green electronics, it is highly desirable to develop a portable, cost-effective, lightweight, and sustainable power source through a facile and environment friendly approach. Herein, we report a portable, flexible, and low-cost selfcharging power system (SCPS) consisting of a paper-based triboelectric nanogenerator (P-TENG) with high output power density as the energy harvester and a paper-based supercapacitor (P-SC) with a great areal capacitance as the energy storage device. A cellulose paper/polypyrrole composite with a low sheet resistance of 7.8 Ω sq −1 replaced the conventional metal electrodes and positive friction material in the P-TENG, as well as the capacitive material in the P-SC. The portable SCPS is capable of driving various miniaturized electronics such as a temperature/humidity indicator, thus demonstrating its potential as a sustainable power source for flexible and miniaturized green electronics.
Rigid polyurethane foam (PU), one of the most promising wall insulation materials, exhibits high flammability and fire risk. In this work, PU/EG/HQ composites with highly effective flame retardancy were fabricated by adding two kinds of flame retardants, expandable graphite (EG) and 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphorylphenanthrene-10-oxide (DOPO-HQ), during the synthesis of polyurethane. Thermal stability and flammability were evaluated using the limiting oxygen index (LOI), thermogravimetric analysis (TGA), UL-94 vertical flame results, and cone colorimeter tests. The as-synthesized PU/EG/HQ composites showed a high LOI value, a maximum peak heat release rate (PHRR) value which was decreased by 58.5% and an increased char yield at 800 C. They also achieved UL-94 V-0 classification.SEM and Raman spectra indicated that the "worm-like" intumescent char layer with a graphitized structure and the formed viscous liquid film were vital factors in the enhancement of the flame retardancy of polyurethane foam in the condensed phase. TG-IR results show that the release of toxic volatiles and flammable gases from the PU/EG/HQ samples was remarkably decreased compared with the release from pure PU. This work associates a gas-solid biphase flame retardancy mechanism with the incorporation of two types of flame retardant and presents an effective method for the synthesis of bi-phase flame-retardant polymers.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.