Surface modification of carbon nanofibers by glycidoxysilane for altering the conductive and mechanical properties of epoxy composites

Carbon nanofibers (CNFs) were functionalized with 3-glycidoxypropyltrimethoxysilane and dispersed into epoxy resin. The chemical modification of CNFs was confirmed by FTIR, SEM, EDX and TGA measurements. After silanization, FTIR showed the existance of epoxy ring; EDX detected Si element; while TGA indicated 1.1 wt.% Si on CNFs. Mechanical properties were analyzed by DMA. Silanized CNFs/epoxy composites demonstrated improved dispersion of CNFs in the matrix, and an enhancement of storage modulus for about 20% compared to the neat matrix, which indicated that the modification of CNFs improved the adhesion between fillers and matrices. DC electrical conductivity of CNFs was reduced about 7-fold compared to the original CNFs due to the silane coating. Accordingly, the composites containing silanized CNFs also had lower electrical conductivity than those containing original CNFs. In spite of decreased electrical conductivity, thermal conductivity of silanized CNFs/epoxy composites was increased due to the surface modification of CNFs.     

Fuel structure and properties of biodiesel produced by the peroxidation process

Biodiesel is a clean alternative fuel, which can be used to reduce the emission pollution from diesel engines. The improvement of fuel properties of biodiesel through production technique was investigated in this study. A chemical production procedure of transesterification reaction combined with an additional peroxidation process was applied to produce the biodiesel. It was shown that the biodiesel produced by this method has a larger weight proportion of saturated carbon bonds, higher kinematic viscosity, and a higher flash point with less fuel residue collected after the fuel burning, than the biodiesel without the additional peroxidation process. Moreover, the peroxide value and the acid number increased while the thiobarbituric acid value, iodine value, combined relative oxidation rate, and number of double bonds of fatty acids reduced for the biodiesel produced with the additional peroxidation process. Therefore, it was concluded that the peroxidation process for biodiesel production can be used to improve the fuel properties of biodiesel.