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.
Dual Cure Phenol - Epoxy Resins: Characterisation and Properties
Reactive blends of 2, 2′- diallyl bisphenol A (DABA) and a novolac epoxy resin (EPN) were investigated for their cure behaviour, and their rheological, physical, mechanical and thermal properties. Cure characterisation was by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The system underwent dual curing through a sequential phenol-epoxy reaction and allyl polymerisation. The former reaction was catalysed by triphenyl phosphine (TPP). Whereas the phenol-epoxy reaction was completed, the allyl polymerization was limited to 40% by the regulation of cure conditions. Increase of epoxy concentration in DABA-EPN blends led to an improvement in the tensile strength and flexural strength of the neat castings. The flexural strength and interlaminar shear strength of the glass laminate showed an improvement with an increase in EPN concentration. Although the crosslink density of the neat casting was enhanced by epoxy-concentration, this did not result in any significant variations in the glass transition temperature (Tg) of the cured matrix. The Tg was in the range 78-82°C. Complete polymerization of all allyl groups resulted in an increase in the Tg and thermal stability while the mechanical properties of the neat system remained practically unaltered. The dual curing of the matrix system resulted in considerable improvement in the flexural properties of their glass composites.
Novel method for the determination of the methoxyl content in lignin by headspace gas chromatography.
The paper reports on a headspace gas chromatographic (HS-GC) method for the determination of methoxyl in lignin. The method involves the quantitive cleavage of methoxyl with hydroiodic acid (HI) to form methyl iodide in a closed headspace sample vial at 130 °C for 30 min. After HI has been added, the sample is neutralized by injecting a sodium hydroxide solution; the methyl iodide in the vial was determined by HS-GC using a flame ionization detector. The results showed that the method has an excellent measurement precision (RSD < 0.69%) and accuracy (RSD < 3.5%) for the quantification of methoxyl content in lignin. The present method is simple and accurate and can be used for the efficient determination of methoxy1 content in lignin and related materials.