Noriyasu Niimura

Prevention of the Reduction of CuO during X‐ray Photoelectron Spectroscopy Analysis

A method to prevent the reduction of CuO formed on Cu metal during x-ray photoelectron spectroscopy analysis is presented. When a bias voltage of -250 V was applied to the sample surface in the case of non-monochromatic Mg Kα 1.2 irradiation, the reduction of CuO to the lower oxide (Cu 2+ →Cu + ) was suppressed by 80-90% as compared with ordinary non-monochromatic x-ray irradiation. The degree of CuO reduction is the same as in the case of monochromatic Al Kα x-ray irradiation. It was found that slow electrons generated from the x-ray window and photoelectrons emitted from the surface by x-ray irradiation cause the reduction. As the reduction can be minimized by applying a bias voltage to the surface, the bias voltage method is very effective for preventing CuO reduction.

Characterization of Rhus vernicifera and Rhus succedanea lacquer films and their pyrolysis mechanisms studied using two-stage pyrolysis-gas chromatography/mass spectrometry

Abstract Rhus vernicifera and Rhus succedanea lacquers, which are used as a surface coating for wood, porcelain and metalware in Japan, were investigated using two-stage pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). Urushiol and laccol components were detected in each lacquer film by pyrolysis at 400 °C. These are the monomers, and are characteristic of Rhus vernicifera and Rhus succedanea lacquer films. In addition, alkenes, alkanes, alkenylphenols and alkylphenols were detected by pyrolysis at 500 °C after pyrolysis at 400 °C. Based on these results, the pyrolysis mechanisms of the respective lacquer films were considered. The pyrolysis products were from the urushiol and laccol polymers. These pyrolysis products clearly reflect the structure of each lacquer film.

Structural study of oriental lacquer films during the hardening process.

Oriental lacquer is the natural resin obtained by tapping lac trees. It hardens into a tough and insoluble film. The extreme hardness and insolubility are some of the most important functions, which are required for industrial coating materials. In this study, two kinds of oriental lacquer films, traditionally named Kiurushi (raw urushi) and Kuromeurushi produced by two different pretreatments, were analyzed during hardening with Fourier transform infrared spectroscopy (FT-IR), thermogravimetry/differential thermal analysis-mass spectrometry (TG/DTA-MS) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) to investigate their functional expression process. Typical functional groups of the lacquer films were detected by FT-IR. The TG/DTA-MS curves clarified that the thermal degradation of the lacquer films gradually began at around 200 degrees C, and reached the fastest rate at 400-500 degrees C. Apparently, FT-IR and TG/DTA-MS could not reveal any difference between the films. On the other hand, Py-GC/MS revealed differences between the films in the peak area ratios of 3-pentadecenylcatechol to 3-pentadecylcatechol and 3-pentadecadienylcatechol to 3-pentadecylcatechol. The ratios of Kiurushi lacquer film were higher than those of Kuromeurushi lacquer film. Both ratios, furthermore, decreased during hardening due to polymerization of the alkenylcatechols into an urushiol polymer skeleton comprising nucleus-side chain and side chain-side chain cross-linkages with 3-pentadecylcatechol at the terminal. The present results suggest that the reaction rate of these cross-linkages in Kuromeurushi lacquer film is faster than that in Kiurushi lacquer film. A good correlation was found between the peak area ratios obtained by Py-GC/MS and hardness obtained by pencil hardening testing. Oriental lacquer expresses the functions - an extreme hardness and insolubility - accelerating the nucleus-side chain and side chain-side chain cross-linkages. Furthermore, it has become clear that the traditional treatments called Nayashi and Kurome effectively accelerate the hardening rate by activating the cross-linkages.

Structural Characterization of Cashew Resin Film Using Two-Stage Pyrolysis-Gas Chromatography/Mass Spectrometry

Technical cashew nut shell liquid (CNSL) was analyzed to investigate its constituents using gas chromatography/mass spectrometry (GC/MS). The results showed that it consists of cardanols and cardols but not 2-methylcardol. After the addition of hexamethylenetetramine to technical CNSL, the mixture was polymerized into the cashew resin film by autoxidation. The film was analyzed using two-stage pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). It was found that the cashew resin is terminated with saturated cardols and cardanols after the pyrolysis at 400°C. This pyrolysis effectively identifies the cashew resin from the other resins and saps. Furthermore, pyrolysis at 500°C revealed that the autoxidative side-chain/side-chain C-C coupling accelerated the cross-linking of trienyl- and dienylcardanols during polymerization.

Structural Studies of Melanorrhoea usitate Lacquer Film Using Two-stage Pyrolysis/Gas Chromatography/Mass Spectrometry

Melanorrhoea usitate lacquer film was investigated using two-stage pyrolysis/gas chromatography/mass spectrometry. Monoenyl and saturated thitsiol components were detected by pyrolysis at 400 °C. The pyrolysis products of the thitsiol polymer, i.e. alkenes, alkanes, alkenylbenzenes, alkylbenzenes, alkenylphenols, alkylphenols and phenylalkylphenols were then detected together with the pyrolysis products of the glycoprotein and thitsiol components, by further pyrolysis at 500 °C. After studying their pyrolysis mechanisms, it was concluded that the lacquer film is terminated with monoenyl and saturated thitsiol components. Alkenes, alkanes, alkenyl- and alkylbenzenes are observed as thermally decomposed components from such terminal chains. Additionally, alkenes and alkanes having carbon chains longer than the side chains of 3-heptadecylcatechol, and alkenyl- and alkylbenzenes having carbon chains longer than C12 are detected as the pyrolysis products of thitsiol polymers formed by autoxidative side-chain/side-chain C—C coupling. Alkenyl-, alkyl- and phenylalkylphenols are the pyrolysis products of the C—O coupling polymer. These facts support the view that the polymerization of thitsiol proceeds through autoxidative side-chain/side-chain C—C coupling and nucleus/side-chain C—O coupling as well as by nucleus/side-chain C—C coupling.

Hardening Process and Surface Structure of Lacquer Films Studied byX‐ray Photoelectron Spectroscopy

The changes of the composition ratios and chemical binding states of the component elements in the surfaces of four varieties of lacquer films during the hardening process were studied by x-ray photoelectron spectroscopy (XPS). Additionally, the relationship between the surface structure and hardening process of lacquer films was studied by the pencil hardness testing method. The relative oxygen contents and the existence ratios among the COO, C=O, C-O-C, C-OH, C-N and N=O functional groups in the surfaces of the lacquer films increased significantly with the progress of hardening. In addition, it was revealed that a lacquer film with a faster hardening rate showed a higher relative oxygen content and a larger existence ratio among these functional groups in the surface. The increases support the progress of the following three phenomena in the surface of lacquer film during the hardening process, i.e. the concentration of gummy substances and nitrogen-containing compounds, laccase-catalysed oxidative polymerization and autoxidative polymerization.

Characterization of synthesized lacquer analogue films using x-ray photoelectron spectroscopy

Four kinds of synthesized lacquer analogue films were characterized using x-ray photoelectron spectroscopy (XPS) and the pencil hardness testing method. The results were compared with natural lacquer film. Laccase-catalysed oxidative polymerization and autoxidation have been found to contribute to the hardening of the synthesized lacquer analogue. Plant gum and glycoproteins are concentrated in the surface of the synthesized lacquer film during hardening, as with the natural lacquer films. Furthermore, synthesized urushiol analogues, in which side chains are richer in the double bond, polymerize into harder lacquer films and concentrate more oxygen and nitrogen in the film surface with proportionately more COO, CO, COC and CN functional groups. The synthesized lacquer films are brilliant and tough like the natural lacquer film. Copyright

Structural Studies and Polymerization Mechanisms of Synthesized Lacquer Films Using Two-stage Pyrolysis-Gas Chromatography/Mass Spectrometry

Abstract Two kinds of synthesized lacquer films were investigated and compared with a natural lacquer film using two-stage pyrolysis-gas chromatography mass spectrometry (Py-GC/MS). Monoenyl and saturated urushiol were detected from the synthesized lacquer film by pyroly-sis at 400°C, as well as from the natural lacquer film. These are attributed to the terminal groups of the synthesized lacquer film. In addition, alkenylphenois. aikyiphenols, alkenes and alkanes were detected by pyrolysis at 500°C after pyioiysis at 400°C. as well as in the natural lacquer film. Some alkenes and alkanes have longer carbon chains than the side chains of synthesized urushiol. The alkenylphenois and aikyiphenols are the pyrolysis products of the nucleus-side chain C-O coupling synthesized urushiol polymers, and the alkenes and alkanes, whose carbon chains are longer than the side chains of synthesized urushiol, are the pyrolysis products of autoxidative side chain-side chain C-C coupling synthesized urushiol polymer. Based ...

Structural Study of a Japanese Lacquer Film with Thermogravimetry-Linked Scan Mass Spectrometry

Japanese lacquer artwork is one of the most famous cultural heritages in Japan. The main component of the Japanese lacquer is urushiol, which consists of phenol derivatives. The dimerization process of urushiol has been investigated in detail, but the structure of urushiol polymer has not. In this study, the structure was investigated by using thermogravimetry (TG)-linked scan mass spectrometry (MS). Linked scan MS is effective in detecting the thermal degradation products of urushiol polymer as the evolved gas. As a result, it is concluded that 3-pentadecylcatechol and 3-pentadecenylcatechol are the main components of the terminal groups of the urushiol polymer, and 3-pentadecatrienylcatechol is a main component of the polymer skeleton.

Structural Characterization of a Modified Cashew Nut Shell Oil Coating Film for Industrial Use

Abstract A modified cashew nut shell oil coating film (CNSO-CF) was produced from the biomass of the oil obtained from the nut of Anacardium occidentale Linn. It dries more quickly than the conventional CNSO-CF. It is, therefore, more suitable to mass production on assembly lines. The modified CNSO-CF was analyzed by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), and its structures were compared with those of the conventional CNSO-CF and of urethane coating film. It was found that the modified CNSO-CF had a urethane coupling structure in addition to the same structures as the conventional CNSO-CF: the methylene cross-linked and autoxidative side chain-side chain C─C coupling structures. The addition of the urethane coupling structure accelerates the drying rate and expresses the most important functions for industrial use – extreme hardness and insolubility.