The research on phenolic resin modified by nanoparticles and used for magnesite-carbon brick binder
The research method use nanoparticles to modify the phenolic resin binder for magnesite-carbon brick. The normal detection indexes of phenolic resins is suited to used as the binder. FESEM images show that the nanoparticles are distributed uniformly without agglomeration almost. The physical-chemical property analyses show that the magnesite-carbon brick using this modified phenolic resin as binder possesses a low apparent porosity and a high bulk density and compression strength. Especially, the compression strength of the magnesite-carbon bricks after heat treatment for 200°C×12h increase to 43.94MPa and 41.35MPa, respectively. The results also show that with the increase of heat treatment temperature, the compression strength and the bulk density of magnesite-carbon bricks decrease and the apparent porosity magnesite-carbon bricks increases. The physical-chemical property shows a significant change from 200°C to 1100°C. However the change is not obviously from 1100°C to 1550°C and shows worse trend with the increase of heat treatment temperature.
Thermal characteristics of addition-cure phenolic resins
Abstract The thermal and pyrolysis characteristics of four different types of addition-cure phenolic resins were compared as a function of their structure. Whereas the propargyl ether resins and phenyl azo functional phenolics underwent easy curing, the phenyl ethynyl- and maleimide-functional ones required higher thermal activation to achieve cure. All addition-cure phenolics exhibited improved thermal stability and char-yielding property in comparison to conventional phenolic resole resin. The maleimide-functional resins exhibited lowest thermal stability and those crosslinked via ethynyl phenyl azo groups were the most thermally stable systems. Propargylated novolac and phenyl ethynyl functional phenolics showed intermediate thermal stability. The maximum char yield was also given by ethynyl phenyl azo system. Non-isothermal kinetic analysis of the degradation reaction implied that all the polymers undergo degradation in at least two steps, except in the case of ethynyl phenyl azo resin, which showed an apparent single step degradation. The very low pre-exponential factor common to all polymers implied the significance of volatilisation process in the kinetics of degradation. Isothermal pyrolysis studies led to the conclusion that in the case of nitrogen-containing polymer, the pyrolysis occurs via loss of nitrogenous products, which is conducive for enhancing the carbon-content of the resultant char. FTIR spectra of the pyrolysed samples confirmed the presence of C–O groups in the char. XRD analysis of the partially carbonised polymers did not give any indication of crystallites except in the case of ethynyl phenyl azo system.
DSC and 13C‐NMR studies of the imidazole‐accelerated reaction between epoxides and phenols
Identification des produits d'addition primaire et secondaire du cresol (o- ou m-) sur le phenyl- ou le glycidyl cresyl ether, composes modeles respectivement d'une novolaque durcissante et d'une novolaque epoxyde cresol, en utilisant les concentrations variables d'accelerateur. Discussion de la selectivite de la reaction. Influence de la concentration de l'accelerateur et de la stœchiometrie sur la Tg de novolaques epoxyde cresol durcies par une novolaque cresol