Electron Beam Irradiation Crosslinking and Flame Retardant of Ethylene Vinyl Acetate Using Melamine-Formaldehyde Microencapsulated.

The microcapsule particles were successfully prepared by means of in-situ copolymerization of layered double hydroxides (LDHs) with the melamine resin monomers, improving the compatibility of inorganic flame retardant LDH with polymer. The electron beam irradiation was introduced into the process to enhance the mechanical properties and thermostability of the flame retardant composite material. The flame-retardant composites were prepared by incorporating the microcapsule LDH into ethylene vinyl acetate (EVA). The compatibility of microcapsule particles with EVA, combustion and thermal behaviors were detected in sequence through SEM, TG analyses, LOI, UL-94 level and mechanical tests. It was shown that the irradiated EVA/LDH@MF composite had showed the best performances of flame retardancy and mechanical properties due to microencapsulation and irradiation processes. The uniform dispersion of microencapsulated LDH in the EVA matrix was due to the good compatibility of MF shell with EVA keeping the mechanical properties of EVA matrix. The irradiated EVA/LDH@MF with 200 kGy dose achieved a limiting oxygen index (LOI) of 25.5% and a UL-94 V-1 rating. When the dose rate was 100 kGy, the EVA/LDH@MF composite had the best mechanical properties of EVA composites. The microencapsulation of LDH with MF shell incorporated into EVA three-dimensioned network through electron beam irradiation induced crosslinking to enhance mechanical properties.

Preparation of a NiAl-Oxide@Polypyrrole Composite for High-Performance Supercapacitors.

A core-shell NiAlO@polypyrrole composite (NiAlO@PPy) with a 3D "sand rose"-like morphology was prepared via a facile in situ oxidative polymerization of pyrrole monomer, where the role of PPy coating thickness was investigated for high-performance supercapacitors. Microstructure analyses indicated that the PPy was successfully coated onto the NiAlO surface to form a core-shell structure. The NiAlO@PPy exhibited a better electrochemical performance than pure NiAlO, and the moderate thickness of the PPy shell layer was beneficial for expediting the electron transfer in the redox reaction. It was found that the NiAlO@PPy5 prepared at 5.0 mL L-1 addition amount of pyrrole monomer demonstrated the best electrochemical performance with a high specific capacitance of 883.2 F g-1 at a current density of 1 A g-1 and excellent capacitance retention of 91.82 % of its initial capacitance after 1000 cycles at 3 A g-1 . The outstanding electrochemical performance of NiAlO@PPy5 were due to the synergistic effect of NiAlO and PPy, where the uniform network-like PPy shell with the optimal thickness made electrolyte ions more easily accessible for faradic reactions. This work provided a simple approach for designing organic-inorganic core-shell materials as high-performance electrode materials for electrochemical supercapacitors.