Joichi Koga

Pyrolysis-GC/FT-IR Analysis for Silane Coupling Treatment of Glass Fibers

Pyrolysis gas chromatography coupled with FT-IR (Py-GC/FT-IR) has been applied to the study of silane treatment of E-glass fiber. The glass fiber treated with a silane coupling agent, γ-anilinopropyltrimethoxy-silane (AnPS), is pyrolyzed at 750°C. The pyrolysates are fractionated by GC and analyzed by FT-IR. The main fraction is assigned to the organofunctional group of the coupling agent. Thus, Py-GC/FT-IR enables us to identify the treated coupling agent qualitatively. A mixture of two different coupling agents, AnPS and γ-methacryloxypropyltrimethoxysilane on glass fiber, is separated and characterized from the spectra of fractions resulting from each coupling agent. Py-GC/FT-IR also provides quantitative information regarding the coupling agents on glass fiber. The total amount of the treated coupling agent is estimated according to the calibration curves, which are proportional to the amount of the coupling agent. Moreover, Py-GC/FT-IR enables us to evaluate the fixing ratio of the coupling agent to the total amount through washing the samples with methanol. The fixing ratio falls significantly above treatment concentration. This tendency is consistent with the results from nondestructive sampling preparation techniques in infrared spectroscopy. The above results indicate the usefulness of Py-GC/FT-IR for the evaluation of silane treatment.

Photoacoustic FT-IR Study on Keratin Chemically Bound on the Surface of Silica Gel Particles

The conformation of keratin chemically bound to the surface of silica gel particles has been investigated by means of photoacoustic Fourier transform infrared (PA/FT-IR) spectroscopy. On the basis of the peak positions of the amide I and amide II bands, it is concluded that the keratin thin layer assumes the native α-helix form. It is also noted that the PA/FT-IR method is the only feasible method for observing the IR spectra of the very thin layer of keratin coating on the silica gel particles. The diffuse reflectance technique failed to provide any information on keratin, because of the strong spectral artifact due to the specular reflection at the surface of the silica gel.

Selective absorption: I. A study of the asymmetric absorption of hydratropic acid, mandelic acid, α-phenethyl alcohol and α-phenethyl amine upon wool from their aqueous solution

SummarySome organic acids, alcohol and amine which have an asymmetric carbon atom were used for an investigation of asymmetric absorption on wool. Racemic mixture of hydratropic acid, mandelic acid andα-phenethylamine have shown the selective absorption on wool from their aqueous and alcoholic aqueous solutions and S-form of their diastereoisomers preferentially absorbed on wool. According to the results we obtained so far, it is concluded that the preferential absorption strongly depends on the configuration of the substance of which wool is composed.

Efficient deacylation of N-acylimidazoles by functionalized surfactant micelles

Hydroxylated surfactant micelles are powerful catalysts for the deacylation of N-acylimidazoles under neutral conditions; the deacylation rates of hydrophobic acylimidazoles are accelerated remarkably by functionalized micelles containing three hydroxy groups at the polar head.

Stereoselective micellar catalysis. Part 5. Deacylation behaviour in the cleavage of enantiomeric esters by optically active catalysts containing the imidazolyl group

The rate constants of both acylation and deacylation in the cleavage of the enantiomers of amino acid p-nitrophenyl esters catalysed by optically active catalysts containing the imidazolyl group have been determined in the presence of surfactant micelles at pH 7.30 in 0.02M-phosphate buffer and 25 °C. The kinetic analysis suggests a nucleophilic mechanism which involves acylation followed by deacylation at the imidazolyl group. Micellar catalysis in deacylation as well as acylation is examined in terms of the rate constants and stereoselectivity. The structural effects of catalysts and substrates and the stereoselective reaction mechanism are discussed.

Asymmetric interaction of optically active polymers with asymmetric small molecules. III. The effect of pH on asymmetric interaction of optically active acidic polymer with tryptophan

The interaction of optically active polymer prepared from L-lysine and adipyl chloride by interfacial polycondensation with D- and L-tryptophan was studied. It was found that selective interaction occurred, and the amount of L-isomer bound to the polymer was greater than that of D-isomer in the range from pH 3.0 to 7.5 at 25°C. At near pH 5.0, the maximum asymmetrical ratio was obtained. The optical rotatory dispersion and viscosity of the polymer were measured. The relationship between conformational differences of the polymer and asymmetric interaction is discussed.

Selective absorption: II. A study of the selective adsorption of optically active alanine derivatives on wool

SummaryThree dyes were synthesized from D-, L-, and DL-alanine, and studied their dyeing behaviors on wool. In the investigation we found that the D-form of the dyes adsorbed on wool most, the L-form adsorbed least, and DL-form fell in between in their acidic aqueous solutions. In an alkaline solution, however, the difference in adsorption behavior on wool between the optical isomers was not detected. We discussed some conditions which lead to the selective-adsorption behavior of optically active dyes on wool.ZusammenfassungDrei Farbstoffe wurden aus D-, L- und DL-Alanin synthetisiert und ihr Färbevermögen für Wolle untersucht. Wir fanden, daß die D-Form der Farbstoffe am besten, die L-Form weniger an Wolle absorbiert wird und die DL-Form in ihren sauren wäßrigen Lösungen dazwischen fällt. In alkalischen Lösungen jedoch wurde kein Unterschied zwischen den optischen Isomeren im Adsorptionsverhalten an Wolle beobachtet. Wir diskutieren die Bedingungen, welche zu dem selektiven Adsorptionsverhalten der optisch-aktiven Farbstoffe auf Wolle führten.