Shigeaki Yonemori

Thermoporosimetry: Pore size distribution measurements for microporous glass using differential scanning calorimetry

The pore size distributions (PSDs) of microporous glass, which were controlled by acid leaching subsequent to phase separation of CaO-Al 2 O 3 -B 2 O 3 -SiO 2 glass, were determined via both mercury porosimetry and thermoporosimetry (thermal porosimetry). As a result, the pore radii, the cumulative pore volumes, and the surface areas determined via thermoporosimetry were in good agreement with those determined via mercury porosimetry. It was revealed that thermoporosimetry could be applied to pore structure analysis for porous materials having pore sizes at least up to 58 nm in radius.

Structural determination of fluoro-organic mixtures by 19F COSY NMR spectroscopy

Abstract A method for the structural determination of mixtures of perfluorinated compounds without material separation was investigated using a simple 19 F COSY NMR technique. Two COSY experiments with different evolution period were used to elucidate complicated coupling constants. Each peak of a molecule was identified in a mixture using a long evolution period and then the peaks of each molecule were assigned using a standard evolution time. The structures of three isomers of chlorotrifluoroethylene trimers were elucidated using the proposed method.

Chemical ionization mass spectrometry of hydrofluorocarbons, hydrofluorocarbon ethers and perfluoroalkenes

Abstract Positive and negative chemical ionization (CI) mass spectrometry is studied for hydrofluorocarbons (HFCs), hydrofluorocarbon ethers (HFEs), and perfluoroalkenes (PFCs) using various kinds of reagent gas. While no quasi-molecular ion was observed under electron impact ionization for saturated MFCs, [M-F] + is detected under CI conditions using methane as a reagent gas. Mechanisms for the generation of [M-F] + are discussed. Furthermore, nitrogen monoxide can be used as a reagent gas to observe [M + NO] + for many HFCs and HFEs. In negative mode chloroform is also available to generate [M + Cl] − for HFCs and HFEs containing -CHF- groups.

Structural determination of chlorotrifluoroethylene dimers by 13C19F INEPT NMR

Abstract The 13C19F INEPT NMR method has been applied to determine the chemical structures of the dimers of chlorotrifluoroethylene synthesized in sulfuryl chloride. These have been identified as a mixture of 1,2,4,4-tetrachlorohexafluorobutane and 1,1,4,4-tetrachlorohexafluorobutane.

Selective degradation of urethane bond of ester-type polyurethanes with pyridine.

Chemical degradation method of ester-type polyurethanes composed of polyesterpolyols, polycaprolactonepolyols, or polycarbonatepolyols was investigated. Pyridine containing water was an effective reagent to hydrolyze urethane bond selectively without cleaving ester bond. One gram of polyurethane sample was heated at 160°C in a mixture of 10 ml of pyridine and 0.5 g of water in a pressure vessel. Urethane bond was completely hydrolyzed after 15 h under this condition. After evaporating the reagent, the molecular weight and composition of the polyols were determined by GPC and NMR. In the case of polycarbonates, a lower decomposition temperature of 130°C was preferable to avoid the cleavage of carbonate bond.

Direct Observation of Interfaces between Glass Fibers and Polymers in Glass Fiber Reinforced Plastics

The interface between glass fibers, which coated with a binder system and matrix polymer in glass fiber reinforced plastics is investigated by means of scanning electron microscope (SEM) and transmission electron microscope (TEM) using new method for making ultra thin specimens. A observation in detail of the interfaces between glass fibers and matrix polymers suggest that the polymer component in binder system diffuse into the matrix polymer except for using highly reactive polymer as the binder component.

Structural Transformation of 4-Hydroxybutyl Vinyl Ether in Solvent-Soluble Fluoropolymer for Paint.

Transformation of 4-hydroxybutyl vinyl ether (HBVE) in an acidic medium was investigated by GCMS and 13C-NMR. The ether monomer was copolymerized as bridging group in solvent-soluble fluoropolymer. The monomer changed into intramolecular 7-membered cyclic compound, 2-methyl1, 3-dioxepane and linear oligomers in intermolecular addition of vinyl and hydroxy groups when the monomer modified with dilute hydrochloric acid. The transformation proceeded fast in acid, though it progressed slowly by heating and did not in alkali at all. Practical paints modified with succinic anhydride contained the linear oligomers originated from unpolymerized HBVE monomer.