Sol-gel Reaction Of Tetraethoxysilane Research Articles

ゾル―ゲル法によるブタジエンゴムのｉｎ ｓｉｔｕシリカ補強に対する反応条件の検討

In situ silica reinforcement of butadiene rubber (BR) was carried out by the sol-gel process using tetraethoxysilane (TEOS). BR was sulfur-cured, and the BR vulcanizates were subjected to soaking in TEOS at 30°C for 48 hours. The swollen samples were soaked in an aq. solution of catalyst under various conditions to conduct the sol-gel reaction of TEOS in the rubber matrix. Further, the vulcanizates were kept at 50°C for 72 hours. The catalyst used in this study was n-butylamine. The resulting vulcanizates were silica stocks by in situ filling technique, and were subjected to tensile tests. The effects of concentration of the catalyst (2, 10, 20wt%) and soaking temperature, i.e., the reaction temperature in the aq. catalyst solution (30, 40, 50°C) on in situ silica filling for reinforcement were discussed in term of tensile properties of the BR vulcanizates. The effect of soaking time (2, 5, 12, 30h) in the catalyst solution was also evaluated for the reinforcement. When the BR vulcanizate was soaked in 2wt% n-butylamine aq. solution at 50°C for 24 hours, the silica content became largest and homogeneous filling was found. Hence, the modulus of the vulcanizates became highest among the samples. The diameter of the in situ filled silica was ca. 30nm. The soaking time did not much influence on the in situ silica reinforcement of the vulcanizates.

Transport properties of polyimide/silica composite membranes.

Polyimide/silica composite membranes were prepared by the sol-gel reaction of tetraethoxysilane, methyltriethoxysilane or phenyltriethoxysilane in the solution of polyamic acid prepared by condensation of equimolar amount of pyromellitic dianhydride, 3, 3′, 4, 4′-biphenyltetracarboxylic dianhydride or 2, 2-bis(3, 4-dicarboxyphenyl)hexafluoropropane dianhydride with 4, 4′-oxydianiline in N-methyl pyrollidone. Silica-coated polyimide membranes were also prepared by the sol-gel method. Gas permeation for H2, CO2, CO, O2, N2 and CH4 and water vapor permeation were reported. A slight reduction in gas permeability was observed for the composite membrane. The permeability of water vapor increased in polyimide/silica composite membranes, while silica coating resulted in a reduction of the permeability. Transient sorption and desorption experiments were also investigated at water vapor activity of 0.5. An increase in permeability of water vapor can be attributable to an increase in solubility of water vapor due to the presence of hydroxy species of silica.

Characterization of spin-coated silicate and phosphosilicate thin films prepared by the sol-gel method

Spin-on glass (SOG) solutions for silicate and phosphosilicate films, respectively, were prepared by the sol-gel reaction of tetraethoxysilane (TEOS) in organic solvent. Fourier transform infrared (FTIR) and temperature-pro-grammed desorption (TPD) measurements were performed to investigate the bond configuration and thermal annealing behavior of the prepared films, respectively. The film properties, such as thickness shrinkage, refractive index and dielectric constant, were measured and correlated with the results of FTIR and TPD. The results of TPD combined with FTIR measurements inferred that the non-hydrolyzed alkoxy groups contained in silicate films were decomposed during the thermal treatment process, causing subsequent degradation of electrical properties of SOG films. Dielectric constants are well correlated with the content of silanol bonds in the films.

ゾルーゲル法によるスチレン‐ブタジェン共重合ゴムのｉｎ ｓｉｔｕシリカ補強，１

In situ silica reinforcement of styrene-butadiene rubber (SBR) was carried out by the sol-gel process using tetraethoxysilane (TEOS). SBR was sulfur-cured, and subjected to welling in tetrahydrofuran and soaking in TEOS with or without catalyst in the presence of small amount of water. The catalyst used was n-butylamine or hydrochloric acid. The swollen vulcanizates were kept at 50°C to conduct the sol-gel reaction of TEOS in the rubber matrix. The resulting vulcanizates were silica stocks by in situ filling technique, and were subjected to the tensile measurement. Increase of modulus and tensile strength at break was recogneized, which suggests inclusion of silica particles in the vulcanizates. The reinforcement effect of in situ silica was highest when n-butylamine was used as a catalyst. This method of filler compounding is promising for diene rubbers as well as for silicone elastomers.