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.
Phenolic resins bearing maleimide groups : Synthesis and characterization
Novel phenolic novolac resins, bearing maleimide groups and capable of undergoing curing principally through the addition polymerization of these groups, were synthesized by the polymerization of a mixture of phenol and N-(4-hydroxy phenyl)maleimide (HPM) with formaldehyde in the presence of an acid catalyst. The polymerization conditions were optimized to get gel-free resins. The resins were char- acterized by chemical, spectral, and thermal analyses. Differential scanning calorime- try and dynamic mechanical analysis revealed an unexpected two-stage curing for these systems. Although the cure at around 275°C was attributable to the addition polymer- ization reaction of the maleimide groups, the exotherm at around 150 to 170°C was ascribed to the condensation reaction of the methylol groups formed in minor quantities on the phenyl ring of HPM. Polymerization studies of non-hydroxy-functional N-phenyl maleimides revealed that the phenyl groups of these molecules were activated toward an electrophilic substitution reaction by the protonated methylol intermediates formed by the acid-catalyzed reaction of phenol and formaldehyde. On a comparative scale, HPM was less reactive than phenol toward formaldehyde. The presence of the phenolic group on N-phenyl maleimide was not needed for its copolymerization with phenol and formaldehyde. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 641- 652, 2000
Polymérisation thermique de la 4-méthoxy-phényl éthynyl cétone, modèle de précurseurs de polymères thermostables
Resume La polymerisation thermique, en masse, de la 4-methoxy-phenyl ethynyl cetone est etudiee par Chromatographie d'exclusion sterique, et par spectroscopie (i.r. et RMN 1 H et 13 C), apres separation chromatographique. Des fractions riches en oligomeres sont separees, permettant d'isoler, purifier et caracteriser le cyclotrimere-1,3,5. Par ailleurs, l'etude de la fraction polymere, majoritaire, conduit a la conclusion que les enchainements sont du type queue-a-queue, un enchainement minoritaire tete-a-queue pouvant expliquer la formation du cyclotrimere. Un mecanisme reactionnel est propose, tenant compte de l'ensemble des observations experimentales.