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Vol 471, No 2 (2016)
- Year: 2016
- Articles: 3
- URL: https://journals.rcsi.science/0012-5016/issue/view/9205
Physical Chemistry
Sulfonated poly(naphthoylenebenzimidazole) and its modification with an alkali metal cation
Abstract
A method for sulfonation of poly(naphthoylenebenzimidazole) with oleum–sulfuric acid mixture to produce sulfonated poly(naphthoylenebenzimidazole)s (SPNBIs) with different content of–SO3H groups has been developed. SPNBIs containing ≥5% sulfur are soluble in NMP and form stable solutions. It has been revealed that viscosity of SPNBI solutions in NMP increases on decreasing concentration when the content of polar sulfonic groups enhances with sulfonation degree of the initial polymer. Thus, SPNBI shows the polyelectrolyte effect. The substitution of hydrogen atoms in sulfonic groups by an alkali metal ion, potassium, has been conducted by the treatment of SPNBI powders with 5 M KOH aqueous solution under heterogeneous conditions. Potassium salts of SPNBI are insoluble in NMP. The introduction of potassium ions into SPNBI leads to the preparation of ionomers with a thermal stability higher than that of the initial PNBI.
195-198
Shift of the nematic–isotropic phase transition temperature in a thin layer of a metallomesogenic complex
Abstract
The effect of boundaries on the nematic–isotropic phase transition temperature in a melt of a metallomesogenic complex was studied for the first time. This was done by comparison of the electro-optical constant of the isotropic phase with the dielectric and optical anisotropy of the nematic phase on the basis of the Landau–de Gennes theory. In a real experiment, the two liquid phases (nematic and isotropic ones) coexist in a range of several degrees around the transition. According to polarization microscopy data, the phase transition temperature decreases by more than 10°C as the metallomesogen layer thickness is reduced from 200 to 5 μm.
199-202
Improving the completeness of combustion of boron particles in a solid-fuel ducted rocket owing to distributed air supply to the secondary combustor
Abstract
A model of combustion of boron particles in ducted rocket using distributed air supply to the secondary combustor was developed for the first time. The completeness of boron combustion in ducted rocket using air supply to the secondary combustor through one outlet or two outlets (distributed air supply) was calculated. It was shown that, in some cases, distributed air supply significantly (by a factor of 1.5–3) decreases the time of complete combustion of boron particles and thereby increases the completeness of fuel combustion in ducted rocket. The modeling results agree with the known experimental data.
203-207