RESUMO
Epoxy resin is extensively applied in the electronics and electrical fields because of its outstanding comprehensive performance. However, the low thermal conductivity (TC) limits its application in thermal interface materials. In the present work, epoxy-based hybrid composites with high TC were prepared by using expanded graphite (EG) and copper (Cu) nanoparticles as thermally conductive hybrid fillers via hot blending and compression-curing processes. Additionally, the influence of the Cu content on the thermal properties, mechanical properties, and morphology of each epoxy/EG/Cu composite was investigated. According to the results, the epoxy/EG/Cu composite showed a maximum TC of 9.74 W/(m·K) at a fixed EG content of 60 wt % owing to the addition of 10 wt % Cu. After the addition of 10 wt % Cu, the flexural strength, flexural modulus, and impact strengths of epoxy/EG/Cu composites were improved from 27.9 MPa, 9.72 GPa, and 0.81 kJ/m2 to 37.5 MPa, 10.88 GPa, and 0.91 kJ/m2, respectively. Hence, this study offers a feasible strategy for the design of epoxy hybrid composites with excellent TC that can be applied to thermal interface materials.
RESUMO
A tandem C-H oxidation/oxa-[3,3] Cope rearrangement/aldol reaction of allylic silylethers promoted by T+BF4-(tempo oxoammonium tetrafluoroborate)/ZnBr2 has been successfully developed allowing the efficient construction of 8-oxabicyclo[3.2.1]octanes and their analogs with a wide substrate scope.
RESUMO
A series of poly (arylene ether ketone sulfone) s containing different amino content (Am-PAEKS) were prepared via direct polycondensation reactions, and then the sulfobutyl groups were grafted onto the Am-PAEKS by amidating reaction between the amide groups in Am-PAEKS and carboxylic acid groups in 4-(N-butane sulfonic) aminobenzoic acid. The structures of the compounds and the polymer were confirmed by FTIR and H-NMR. The new characteristic bands at 1 239 and 1 060 cm(-1) were assigned to O=S=O symmetric stretching vibration and asymmetric stretching vibration of the sulfonic groups in sulfonated poly (arylene ether ketone sulfone) on side chain (S-SPAEKS), and the structures of the polymers were further confirmed by 1H NMR spectra, and the proton peak at 1.64 ppm was assigned to the methyl in the middle of the pendant sulfonated aliphatic side chains, which show that the S-SPAEKS had been prepared successfully. In TGA curves we can observe two distinct weight loss steps, the first step was mainly attributed to the splitting-off of the sulfonic acid groups at 300 degrees C, and the second step was mainly attributed to the decomposition of the main chain of the S-SPAEKS at 450 degrees C. This series of SSPAEKS polymers exhibit excellent thermal properties by thermo gravimetric analysis, which can satisfy the basic requirements of proton exchange membrane (PEM) for fuel cells.
RESUMO
A series of novel Sulfonted poly(arylene ether sulfone)s (SPAES) containing 1,3,4-oxadiazole are prepared via direct polycondensation reactions to precisely control the degree of sulfonation. The structures of these compounds were confirmed by FTIR, H-NMR and TGA. The characteristic peaks of transmittances spectra of C=N were found at 1 603 cm(-1) and by H-NMR further confirm the structures, which has been successful introducing the oxadiazole ring. In each TGA curve can observe two distinct weight loss steps, which the one at 300 degrees C and the second at 450 degrees C were mainly attributed to the splitting-off of sulfonic acid groups and decomposition of the main chain of the SPAES. The TGA exhibit excellent thermal properties may be satisfied with the basic requirements of proton exchange membrane (PEM) for fuel cells.
