Synthesis of Rhus succedanea lacquer film and analysis by pyrolysis-gas chromatography/mass spectrometry

Laccol, a major component of lacquer sap from Rhus succedanea, was synthesized by a Witting reaction, and then mixed with acetone powder separated from raw lacquer sap to synthesize lacquer films. The resulting lacquer films were analyzed by pyrolysis gas chromatography/mass spectrometry (Py-GC/MS), and the results were compared with that of natural lacquer film to evaluate the polymerization mechanism and film structure. The results showed that saturated and monoenyl laccol components were present only in the natural lacquer film, but not in the synthesized lacquer films. Meanwhile, alkylphenols, alkebulphenols, alkanes, and alkenes having longer carbon chains than the side chains were detected in the synthesized laccol, suggesting that the polymerization of synthetic laccol proceeds through the laccase-catalyzed nucleus-side chain CO coupling and autoxidative side chain to side chain CC coupling like natural lacquer film. The synthesized laccol films showed shallow color and hardness, which would make them useful as good preservative surface-coating materials.     

Analysis and Characterization of Korean Lacquer

Three kinds of Korean lacquer saps were analyzed including chemical composition, enzymatic activity, molecular weight distribution, unsaturated degree of side chain, and drying property. The results were compared with Chinese and Japanese lacquer saps all collected in the same month (August 2012 and 2013) to investigate similarities and differences. Compared with Chinese and Japanese saps, the Korean lacquer sap contains the most lipids (84.9%) and urushiol triene (56.1%) components and the second highest enzyme activity after Chinese lacquer sap. In the drying and film hardness test, Korean and Chinese film reached a stronger hardness sooner than Japanese lacquer film; in 21 days the former reached 2H and the latter only H. The results of IR, NMR, and GC-MS analysis showed slight differences due to different growing conditions.     

Deterioration of surface structure of lacquer films due to ultraviolet irradiation

The mechanism of deterioration due to ultraviolet irradiation of black (with iron ion) and kurome (translucent) lacquer films that had been dried at 15–20 °C in 60–70% relative humidity environment was revealed. The lacquer film changes were evaluated by observations of the surface by microscopy, IR, and XPS. A particulate material and toroidal shapes appeared in the black lacquer film during UV irradiation within 48 h, but they did not appear in the kurome lacquer film under UV irradiation before 240 h. The IR peak at ～3445 cm^?1 increased owing to the hydroxyl group, and the C 1s peak decreased and O 1s increased in the XPS spectra as the UV irradiation time increased, implying that a chemical reaction occurred on the surface of the lacquer film. On the top surface of the coating film, many toroidal shapes were observed in the black lacquer film, which showed that the black lacquer film deteriorated more quickly than the kurome lacquer film. In addition, the structural changes in the black lacquer film are also discussed in detail, on the basis of the results of the Py‐GC/MS measurement. Copyright © 2006 John Wiley & Sons, Ltd.     

Thermal degradation behavior of Copoly(propylene carbonate ε-caprolactone) investigated using TG/FTIR and Py-GC/MS methodologies

Thermal degradation behaviors of copoly(propylene carbonate ε-caprolactone)s (PPCCLs) with different ε-caprolactone (CL) contents were studied at various pyrolysis temperatures by the combination of thermogravimetric analysis/Fourier transform infrared spectrometry (TG/FTIR) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) techniques. TGA curves of the copolymers clearly show two stages. The experimental results indicate that the increase of CL content in PPCCL chain leads to an increase of both first and second stage maximum decomposition temperature. The dominant degradation pathway is a backbiting ester interchange reaction involving OH chain ends of PPCCLs, resulting in the formation of cyclic oligomers. In addition, at a relative higher pyrolysis temperature, besides the major products propylene carbonate and caprolactone, some diol and long chain chemicals with ester group were also detected, showing a main intramolecular transesterification accompanied with chain scission decomposition mechanism.     

A degradation study of waterborne polyurethane based on TDI

The thermal degradation of synthetic waterborne polyurethane (PU) based on toluenediisocyanate (TDI) was investigated by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and thermogravimetry (TG). The degradation profiles of cast films obtained from dispersions were evaluated. More than 20 characteristic volatile pyrolyzates reflecting the structure and pyrolysis mechanisms of the polymer have been identified by on-line MS. The synthesized products of polyurethane were pyrolyzed at 350, 450, 550, 650 and 750 °C respectively, and the analysis results revealed that the pyrolyzates distribution of the polyurethane depends strongly on the pyrolysis temperature. The aqueous polyurethane thermogravimetric measurements were used to study the kinetics of thermal degradation.     

Thermal stability and degradation behavior of hydroxyethyl methacrylate-poly(lactide) polymers

Hydroxyethyl methacrylate (HEMA)-Poly(L-lactide) (PLA) polymers, with different molar ratios of HEMA/lactide (1/4 and 1/8), were synthesized by ring-opening polymerization. The thermal degradation behavior and kinetic parameters of these obtained HEMA-PLA polymers were analyzed by thermogravimetric analysis (TGA) and Pyrolysis-Gas chromatography/Mass spectrometry (Py-GC/MS). It was found that the activation energies of thermal degradation of the polymers increased as the residue weight was decreased, indicating that the mechanism of thermal decomposition changes during the process progress. The results showed that the random chain scission proceeded at lower temperature, and subsequently the specific chain scission did so. Moreover, the results revealed that thermal stability of PLA was increased by the copolymerzation of HEMA. In addition, Py-GC/MS analysis showed that the main decomposed products obtained from the HEMA-PLA polymers were HEMA, lactide, dimer, trimer and tetramer.     

Py-GC/MS在VDF/CTFE共聚物链段结构和其裂解机理研究上的应用

用高分辨裂解气相色谱 质谱联用技术 (Py GC/MS)分析了VDF/CTFE(1∶4)链段结构和裂解机理。通过对实验条件的选择 ,找出了一套适合于VDF/CTFE(1∶4)共聚物的实验操作条件 ,且表明在此条件下所得的裂解谱图的重现性非常好。讨论了该共聚物具有无序的链段结构特征 ;确定此共聚物裂解机理为解聚断裂生成单体 ,还伴随有主链断裂形成低聚物     

Molecular criteria for discriminating museum Asian lacquerware from different vegetal origins by pyrolysis gas chromatography/mass spectrometry

This paper focuses on the identification of several chemical markers of vegetal species of Oriental lacquers with the aim at providing a methodology consistent with sampling restrictions necessarily applied in the field of cultural heritage. The method proposed is based on rapid and easy single step thermally assisted hydrolysis–methylation (THM) pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) analysis that can be carried out with a minimum amount of matter (typically 10 μg for a sample collected on a museum or an archaeological object).     

添加改性松香对生漆漆膜性能的影响

通过添加松香、改性松香对生漆漆膜进行改性,研究结果表明,加入改性松香能改善生漆漆膜性能,在反应温度为80℃时,加入生漆质量5％的聚合松香效果最佳,附着力为1级,抗冲击力为35kg／cm,铅笔划痕为3H。反应温度对漆膜性能有很大影响,当加入生漆质量5％的聚合松香,反应温度从50℃升至80℃时,附着力从3级提高到1级,抗冲击力从10kg／cm提高到35kg／cm,铅笔划痕从H升至3H。红外光谱分析表明,天然松香对生漆性能的增强效果是由于与生漆发生了化学反应,而聚合松香对生漆性能的增强效果是协同作用造成的。     

TRANS-1,4,5,8-tetraazodecalin crystals occurring in ethylenediamine

Composition and structure of crystals of unknown origin, crystallizing spontaneously from ethylenediamine on standing, has been determined by elemental analysis, FTIR, ¹H and ¹³C NMR spectroscopy and X-ray diffraction. The crystal with molecular formula C6H14N4 has been found to be a highly symmetric saturated imino compound with double-ring structure, and unambiguously identified as trans-1,4,5,8-tetraazodecalin by ¹H NMR and powder X-ray diffraction based on both its specific AA'BB' spin coupling system and simulated XRD pattern calculated from available data of previous single crystal structure determination, respectively. Simultaneous TG/DTA measurement shows one-step degradation of this compound. The volatile decomposition products have been followed by both TG/DTA-MS and TG-FTIR. Group of the largest fragments (m/z=80, 81 and 82) observed by TG/DTA-MS corresponds to an aromatic 1,4-diazine (pyrazine). In the EGA-FTIR spectrum of released gaseous species measured at the highest evolution rate by TG-FTIR, ethylenediamine can be identified as another decomposition product. This revised version was published online in July 2006 with corrections to the Cover Date.     

Study on the thermal degradation of high performance fibers by TG/FTIR and Py-GC/MS

The thermal degradation behaviors of Kevlar 49, Kevlar 129 (Poly(p-phenylene terephthamide), Nomex (polyisophthaloyl metaphenylene diamine), and PBO(poly(p-phenylene benzobisoxazole)) fibers were measured by TG/FTIR and Py-GC/MS. The characteristic temperatures of the fibers in air were obtained by TG. It indicated that the initial degradation temperature of the PBO is the highest. The initial degradation temperature of Nomex fiber is the lowest, but the end decomposition temperature of Nomex is the highest. The gases released by the pyrolysis in air were mainly CO₂, CO, H₂O, NO, and HCN, also containing a small amount of NH₃, and the absorption peaks of CO₂ were the strongest. The results of Py-GC/MS showed that CO₂ and benzene were the most pyrolysis fragment. With the change of pyrolysis temperature, the chromatogram and mass spectra results take a large variety. The pyrolysates can help us to study the pyrolysis process of high performance fibers.     

New approach for the kinetic analysis of cellulose using EGA-MS

This paper describes a new approach for kinetic analysis based on evolved gas analysis-mass spectrometry (EGA-MS) using pyrolyzer-gas chromatography/MS (Py-GC/MS). The kinetic results derived by this model-free kinetic analysis using the EGA-MS thermograms of cellulose were comparable to those using thermogravimetric analysis (TGA). The activation energies were in the range of 149–194 kJ/mol (mean 169 kJ/mol) for EGA/MS and 152–181 kJ/mol (mean 165 kJ/mol) for TGA. This suggests that Py-GC/MS can be used not only for the qualitative analysis of pyrolyzates, but also for the kinetic analysis of pyrolysis.     

Characterization of selected paper documents from the archives of Palazzo Ducale (Venice), Italy using various analytical techniques

The paper manufacturing process remained unchanged for many centuries, until, in the nineteenth century, the crisis of rags led industrialized countries to patent new production processes with different raw materials. This study deals with this period of transition by analyzing four samples stored at the archives of Superintendency Beni Architettonici per il Paesaggio e per il Patrimonio Storico Artistico ed Etnoantropologico (BAPPDAD) of Venice Lagoon, based in the Palazzo Ducale.The samples were analyzed by FT-IR (ATR), SEM-EDS, HPLC-MS/MS and Py-GC/MS. These techniques allow the characterization of various raw materials and adhesives used in various stages of paper production.These analyses have found a gradual introduction of ground wood in the composition of papers from the mid-nineteenth century, and the use of rosin as glue only in more recent documents.     

Study on pyrolysis behaviors of L-tyrosine-based phthalonitrile resin

The pyrolysis behaviors of l-tyrosine-based phthalonitrile(TPN) resin were investigated by thermogravimetric-Fourier transform infrared spectrometry-mass spectrometry (TG-FTIR-MS) and Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The small molecules produced during pyrolysis process of TPN resin were tracked in real time by TG-FTIR-MS. The larger molecules (m/z > 40) from fast pyrolysis at 900 °C of the TPN resin using Py-GC/MS were identified. From TG-FTIR-MS and Py-GC/MS results, the production pathways of pyrolysis products such as CO₂, CO, NH₃, benzonitrile and phenol were analyzed. The possible pyrolysis mechanism of TPN resin under non-oxidizing gaseous environment was proposed. The results of this study provide the useful information for designing the molecular structure of l-tyrosine-based polymers which possessing high thermal stability.     

Pyrolysis-GC/MS and TG/MS study of mediated laccase biodelignification of Eucalyptus globulus kraft pulp

Biobleaching studies using laccase mediator system (LMS) were carried out, under optimized conditions, on two unbleached Eucalyptus globulus kraft pulps, one produced by conventional way, with kappa number of 16.1, and another with kappa number of 14.5, obtained by modified kraft procedure with a high liquor/wood ratio and with black liquor replacement in the middle of the cooking. The pulp properties before and after LMS and alkaline extraction were evaluated in terms of kappa number, hexeneuronic acid content, viscosity, brightness and acid insoluble lignin content.The original milled wood sample and the kraft pulps were characterized by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and thermogravimetry/mass spectrometry (TG/MS). Eucalypt wood lignin produces guaiacol and syringol derivatives during pyrolysis. These lignin products can be detected with high sensitivity using the selected ion chromatograms even in the bleached pulp of low lignin content (about 0.5%). Py-GC/MS revealed that the lignin moieties were similarly altered during biobleaching as during pulping, which is exemplified by the preferential removal of aldehyde groups from the alkyl side groups. Semi-quantitative analysis of the pyrograms indicates that the lignin content of the biobleached pulps is reduced by about half in comparison with the unbleached pulps. The TG/MS results show that the hemicellulose content of wood was strongly modified during pulping resulting in higher thermal stability.     

Synthesis,odor characteristics and thermal behaviors of pyrrole esters

A novel approach for transesterification of methyl pyrrole-carboxylate with alcohols is reported. The transformation is performed with t-BuOK and a series of new pyrrole ester were obtained under the optimized conditions. The odor characteristics of the pyrrolyl esters were evaluated by GC–MS-O (gas chromatography-mass spectrometry-olfactometry). Among them, compounds of 4-isopropylbenzyl 1H-pyrrole-2-carboxylate (3d) and naphthalen-2-ylmethyl 1H-pyrrole-2-carboxylate (3 l) present nuts and almond-like aroma, respectively. The Py-GC/MS (pyrolysis–gas chromatography/mass spectrometry) approach was applied to evaluate the pyrolysis intermediates of the pyrrole esters in oxidative conditions. It clarified that 3d and 3 l occurred different degrees of pyrolysis throughout the pyrolysis temperature from 30 °C to 900 °C. In addition, the TG (thermogravimetry) and DSC (differential scanning calorimeter) approaches were applied to investigate at the thermal degradation process. They have good thermal stability under certain temperature according to the results of TG analysis.     

文物中多糖类胶结材料的热裂解-气相色谱/质谱识别

热裂解-气相色谱/质谱(Py-GC/MS)技术能够实现微量样品中有机组分的准确、快速检测,非常适用于文物中各类天然有机材料的定性分析。该研究以中国古代书画、建筑、器物等文化遗产中常用的淀粉、桃胶,以及西方文化遗产中常用的阿拉伯胶等多糖类胶结材料为研究对象,系统分析并总结各类材料的Py-GC/MS特征裂解组分及辨别方法。研究发现,淀粉、桃胶、阿拉伯胶在色谱保留时间前段的裂解产物基本一致,主要是小分子呋喃、酮类组分;在保留时间中段3类材料的裂解产物主要是呋喃型酮等组分,但不同材料的具体裂解组分差异明显;在保留时间后段,3类材料检出多种单糖衍生物以及单糖低聚体衍生物,其中桃胶与阿拉伯胶裂解组分较为接近,但与淀粉完全不同。因此,可根据不同保留时间段淀粉、桃胶、阿拉伯胶裂解产物的差异实现3类材料的辨别,其中1,6-脱水-β-D-吡喃葡萄糖只在淀粉中检出且色谱峰强度高,可以作为识别淀粉的特征组分;此外,可根据桃胶、阿拉伯胶在保留时间后段的裂解产物主要质谱碎片离子m/z 60、m/z 101的提取离子流图分布特征实现其辨别。基于所建立的Py-GC/MS方法,研究推断故宫旧藏清代剔红云龙纹天球瓶瓶口部...     

Influence of thermal treatment on the ion-storage capacity of Ce oxide and Ce-V mixed oxide films

Thin films and the corresponding xerogels of CeO₂ and Ce-V mixed oxides with a molar ratio equal to 2 (Ce/V=2) were prepared from CeCl₃·7H₂O and NH₄VO₃ precursors using the sol-gel route and the dip-coating technique. The thermal decomposition of both forms of samples (thin films and xerogels) were studied by dynamic TG and DSC in two different atmospheres (air and argon). For the thermal studies the thin films were deposited on aluminium foil to reduce the unfavourable substrate to film mass ratio S/F, which is a consequence of using a glass substrate. The mode of heat treatment in a tube furnace of films deposited on conductive glass was defined from the TG curves of the films. The influence of annealing conditions (temperature, atmosphere and time) on the charge capacity of the films during application of the cycling process is reported.     

DSC-, TG- und TMA-uUntersuchungen an lacken

DSC measurements on lacquers give information on possible uses, curing conditions and curing time. These data allow optimizing the processing of lacquers. TMA measurements of the glass transition and the softening of films of laquers permit making statements as to baking temperatures, elasticity, and degree of cure of the film of lacquer. Thermogravimetric investigations on the film of lacquer allow drawing conclusions as to the curing process that has taken place within the film and the degree of decomposition by heat and/or oxidation.     

Molecular identification of Asian lacquers from different trees using Py‐GC/MS and ToF‐SIMS

Traditional Asian lacquers are natural products with highly valued properties, including beauty, gloss, and durability. Pyrolysis‐gas chromatography/mass spectrometry is the technique of choice to study insoluble polymeric lacquer films. In the present study, pyrolysis‐gas chromatography/mass spectrometry results showed that the pyrolysis products of lacquer films were different for all of the studied trees, with urushiol derivatives detected in Toxicodendron vernicifluum from China, Japan, and Korea; laccol in Toxicodendron succedaneum from Vietnam; and thitsiol in Gluta usitata from Myanmar. Time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) was also used to characterize the Asian lacquers, avoiding the time‐consuming and destructive processes of other techniques. The ToF‐SIMS spectra provided structural characterization of a series of urushiol, laccol, and thitsiol derivatives for T vernicifluum from China, Japan, and Korea; T succedaneum from Vietnam; and G usitata from Myanmar, respectively. To differentiate the ToF‐SIMS results for the different Asian lacquer films, principal component analysis was used because it can extract differences in the spectra and indicate what peaks are responsible for these differences. The results indicate that lacquer films from different lacquer trees can be very different. Therefore, ToF‐SIMS with principal component analysis is suitable for the characterization and differentiation of Asian lacquer films in cultural heritage applications.