Photochemical degradation study of polyvinyl acetate paints used in artworks by Py–GC/MS

Photochemical degradation of commercial polyvinyl acetate (PVAc) homopolymer and PVAc paints mixed with burnt umber, cobalt blue, cadmium red dark, nickel azo yellow and titanium white commonly used for artworks were studied by pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS) and Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR). Py–GC/MS with single-shot technique was used for the characterization of the thermal degradation of PVAc at different temperatures, while the double-shot technique of Py–GC/MS was used to reveal the differences in the specimens before and after UV ageing, including the changes of detectable amounts of deacetylation product – acetic acid and plasticizers such as diethyl phthalate (DEP). Furthermore, the relative concentration of the pyrolysis products of the paint samples could be measured and compared in the second step of the double-shot Py–GC/MS, which are highly dependent on the presence of pigments and the ageing status of PVAc paints.     

Thermal degradation behaviour and kinetic analysis of unsaturated polyester-based composites and IPNs by conventional and modulated thermogravimetric analysis

The thermal degradation behaviour of epoxy/unsaturated polyester based polymer interpenetrating networks (IPNs), and unsaturated polyester containing various flame-retardants have been investigated by TGA and Py/GC/MS. The kinetic parameters of various polymers were analysed by conventional and modulated thermogravimetric analysis (MTGA) methods. The activation energies of degradation were calculated by the Coats-Redfern and MTGA methods, respectively. The results of both conventional and MTGA analyses reveal that the decomposition of IPNs consists of two non-interfering decomposition processes for epoxy polymer and cured unsaturated polyester, respectively. For the flame-retardant containing unsaturated polyesters, ammonium polyphosphate (APP) played an important role in the second-step of the pyrolysis reaction of APP-containing samples. It is important to note that the possibilities of reaction order for these pyrolysis processes are significantly distinguishable by Coats-Redfern method. Furthermore, the activation energies for various samples calculated by MTGA method are on average larger than those calculated from the Coats-Redfern method. The results also reveal that when either the flame-retardant or the epoxy was added to the unsaturated polyester, the heat resistance of the unsaturated polyester was enhanced.     

A Review of Synthetic Polymer Characterization by Pyrolysis–GC–MS

Pyrolysis–GC with mass spectrometry detection (Py–GC–MSD) study of the thermal degradation products of synthetic polymers is reviewed. Due to the high heating speed, accurate temperature reproducibility and a wide temperature range, Py–GC–MSD has been applied successfully for polymer characterization. Introduction of samples using the pyrolysis carrier gas through the split injection port, followed by sub-ambient cryofocusing of the pyrolysis products, has shown to give reproducible chromatograms (pyrograms). One of the advantages of this method is that all compositions of the polymers and additives can be investigated without any pretreatment, providing important compositional and structural information in a simple way. The method is a convenient method for compositional analysis of complex polymer materials. The aim of this review is to describe the kinds of applications for which Py–GC–MSD has been found to be suitable; to present guidelines for method optimization; to survey innovations that have recently been developed or are currently being researched; to point to problems in our understanding of the pyrograms; and to suggest areas in which research efforts might be most effective in realizing the full potential of this technique.     

Identification of polymer building blocks by Py–GC/MS and MALDI-TOF MS

The main goal of this work is to identify polyurethane (PU) building blocks by pyrolysis gas chromatography/mass spectrometry (Py–GC/MS) and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). Toluene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI) are widely used polymer building blocks. Py–GC/MS and MALDI-TOF MS were proved to be powerful methods to distinguish TDI-PU and MDI-PU according to the characteristic pyrolysis products and the different repeated units, respectively. In Py–GC/MS, the specific pyrolyzates are TDI for TDI-PU and MDI for MDI-PU. In MALDI-TOF MS, the weights of repeated units are 264?g/mol for TDI-PU and 340?g/mol for MDI-PU.     

Rapid methods of polymer and polymer additives identification: Multi-sample solvent-free MALDI, pyrolysis at atmospheric pressure, and atmospheric solids analysis probe mass spectrometry

Polymer manufacturers add antioxidants, waxes, dyes, and other materials to enhance polymer utility or processing. Numerous analytical methods are available to characterize various chemical aspects of polymers including methods interfaced with mass spectrometry (MS) such as pyrolysis (Py), gas chromatography (GC), liquid chromatography (LC), and thermogravimetric analysis (TGA). Current methods work well, but because of the necessity of extraction, chromatography, or thermal methods, most are too time consuming for high throughput analyses which might be necessary in, for example, regulatory laboratories. Here we discuss three MS methods for rapid analysis of polymers; multi-sample MALDI MS which allows rapid analysis of low molecular weight polymers, atmospheric pressure (AP) solids analysis probe MS for direct ambient additives analysis, and APPy MS for polymer identification. The latter methods provide information regardless of the composition or molecular weight of the polymeric material.     

Pyrolysis of flame retardants and fire protected polymers

The simultaneously working combination of thermal analysis and mass spectrometry (TA/MS) is a very useful method for studying the degradation process of polymeric materials during thermal treatment [1–7]. Beside the thermal effects, as recorded from thermogravimetry (TG) or differential thermal analysis (DTA) the evolved degradation products can be determined and identified by the on - line coupled mass spectrometer. Additional their temperature depending abundance can be registrated. Combustion of polymers in horizontal (BIS) or vertical (VCI) furnaces and subsequent off line high resolution GC/MS analysis of pyrolysis products is suitable for the simulation of burning processes     

聚亚苯基苯并二噻唑与聚亚苯基苯并二噁唑的热分解

用高分辨裂解气相色谱 质谱（ＨＲＰｙＧＣ ＭＳ）研究了聚亚苯基苯并二噻唑、聚亚苯基苯并二唑的热分解行为,鉴定了相应裂解产物的组成、分布及其与高分子结构的关系,并用热重法（ＴＧ）测定了它们的热分解反应动力学参数,提出了其热分解反应机理     

FTIR及Py-GC/MS定性分析高聚物单体

红外光谱反应出的是特征化学基团的振动 ,对于高聚物的具体单体组成分析 ,只能借助于紫外光谱、核磁共振及质谱进行综合判断才能得到圆满的鉴定结果[1,2 ] 。本工作针对在红外光谱仪不能分辨的情况下通过气相色谱 质谱联用技术进行综合分析鉴定 ,结果可为其它高聚物分析研究提供实验依据。1　实验1 1　仪器及试验条件未知高聚物试样为白色颗粒状 (晨光化工二厂 )。ＳＹＳＴＥＭ2 0 0 0ＦＴＩＲ ,ＰＥ公司造ＩＲ谱仪 ;ＣＤＳ2 0 0 0铂金丝裂解器 ,裂解室温度 2 5 0℃ ,裂解温度 6 0 0℃ ,升温速率 1 40℃ ｍｓ;ＨＰ6 890型 ,Ｃｏｍｐｏｎｄ…     

Thermal Degradation Processes in Poly(acyl sulfides) Investigated by Pyrolysis–Gas Chromatography/Mass Spectrometry

A series of poly(acyl sulfides) were synthesized by polycondensation of acid dichlorides with sodium sulfide using tetrabutylammoniumhydrogen sulfate as a phase transfer catalyst. The thermal stability of these polymers was determined by thermogravimetric analysis. A unique phenomenon of exothermic degradation behavior was observed by differential thermal analyses, which is attributed to the energetics of the acylsulfide linkage during the thermal degradation. The mechanism of formation of degradation products was investigated by the pyrolysis–gas chromatography/mass spectrometry (Py‐GC/MS) technique.

The acylsulfide linkage containing polymers synthesized exhibit unique degradation behavior.     

Differentiation of resin-modified paints by pyrolysis-gas chromatography/mass spectrometry and principal component analysis

The combination of pyrolysis (Py) with gas chromatography/mass spectrometry (GC/MS) is already well established for polymer analysis. A first approach is reported using this method for detailed quality monitoring of a complex technical polymer system. Six similar solvent-based paints (one standard and five modifications) have been used for evaluation. The major pyrolysis products were identified and qualitative and quantitative modifications were detected and specified. Principal component analysis (PCA) was applied for visualization of differences and similarities.     

Differentiation of resin-modified paints by pyrolysis-gas chromatography/mass spectrometry and principal component analysis

The combination of pyrolysis (Py) with gas chromatography/mass spectrometry (GC/MS) is already well established for polymer analysis. A first approach is reported using this method for detailed quality monitoring of a complex technical polymer system. Six similar solvent-based paints (one standard and five modifications) have been used for evaluation. The major pyrolysis products were identified and qualitative and quantitative modifications were detected and specified. Principal component analysis (PCA) was applied for visualization of differences and similarities.     

In situ monitoring the thermal degradation of PCPDTBT low band gap polymers with varying alkyl side‐chain patterns

The degradation pattern of a series of low band gap PCPDTBT polymers under thermal stress is investigated by in situ UV–vis and FT‐IR techniques combined with thermal degradation analysis. Thermogravimetric analysis is used to predetermine the decomposition intervals, revealing that thermolysis occurs in two stages. TG‐TD‐GC/MS shows that loss of the alkyl side chains predominantly happens within the first temperature regime and degradation of the polymer backbone occurs thereafter. UV–vis spectroscopy is used to monitor the evolution of the optical properties upon heating, reflecting the thermal stability of the conjugated backbone, whereas FT‐IR spectroscopy is applied to evaluate the chemical changes under thermal stress, with an emphasis on the polymer periphery. The influence of the side chains and possible defects, dependent on the synthesis protocol applied, on the thermal stability of the final polymers is discussed and is related to the application of said materials in organic photovoltaics. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4912–4922     

Thermal degradation mechanism of poly(arylene sulfone)s by stepwise Py‐GC/MS

The thermal degradation of poly(ether sulfone) (PES) and polysulfone (PSF) was studied with a combination of thermogravimetric analysis and stepwise pyrolysis–gas chromatography/mass spectrometry techniques with consecutive heating of the samples at fixed temperature intervals (100 °C) to achieve narrow‐temperature pyrolysis conditions. The individual mass chromatograms of various pyrolysates were correlated with pyrolysis temperatures to elucidate the pyrolysis mechanism. The major mechanism for both PES and PSF was a one‐stage pyrolysis involving main‐chain random scission and carbonization. The major products SO₂ and phenol were released from the sulfone and ether groups in PES. The major products SO₂, phenol, and 1‐methyl‐4‐phenoxybenzene were released from the sulfone, ether, and isopropylene groups in PSF. In the PES, the thermal stability of the sulfone and ether groups was identical to the maximum thermogravimetric loss rate. In the PSF, the thermal stability was in the following order: sulfone < ether < isopropylene. The temperature of the maximum thermogravimetric loss rate was similar to the maximum evolution of phenol. However, there was a considerable difference in the thermal behavior of both polymers; the correlation of the polymer structure to the degradation mechanism is discussed. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 583–593, 2000     

Prediction of Klason lignin and lignin thermal degradation products by Py–GC/MS in a collection of Lolium and Festuca grasses

A rapid method for the analysis of biomass feedstocks was established to identify the quality of the pyrolysis products likely to impact on bio-oil production. A total of 15 Lolium and Festuca grasses known to exhibit a range of Klason lignin contents were analysed by pyroprobe–GC/MS (Py–GC/MS) to determine the composition of the thermal degradation products of lignin. The identification of key marker compounds which are the derivatives of the three major lignin subunits (G, H, and S) allowed pyroprobe-GC/MS to be statistically correlated to the Klason lignin content of the biomass using the partial least-square method to produce a calibration model. Data from this multivariate modelling procedure was then applied to identify likely “key marker” ions representative of the lignin subunits from the mass spectral data. The combined total abundance of the identified key markers for the lignin subunits exhibited a linear relationship with the Klason lignin content. In addition the effect of alkali metal concentration on optimum pyrolysis characteristics was also examined. Washing of the grass samples removed approximately 70% of the metals and changed the characteristics of the thermal degradation process and products. Overall the data indicate that both the organic and inorganic specification of the biofuel impacts on the pyrolysis process and that pyroprobe–GC/MS is a suitable analytical technique to asses lignin composition.     

Characterization of poly(styrene‐co‐methacrylonitrile)s obtained by low‐temperature radiation polymerization and thermal degradation behavior measured by Py‐GC and CRTG

Poly(styrene‐co‐methacrylonitrile)s were polymerized in solutions with different polarities (n‐hexane and THF) by low‐temperature γ‐ray irradiation polymerization in a temperature range of −83.6–30 °C. It was found by IR measurement that the composition of the copolymers changed remarkably due to the effects of the polarity of solvents and the polymerization temperature. The thermal degradation behavior in the flash pyrolysis and in the continuous heating pyrolysis of these copolymers was measured by Py‐GC and controlled rate thermogravimetry (CRTG). The effects of the copolymer composition and sequence distribution on the thermal degradation behavior were investigated. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3569–3577, 2000     

Characterization of the chemical differences between solvent extracts from Pu-erh tea and Dian Hong black tea by CP–Py–GC/MS

Solvent extracts from a type of Pu-erh tea and Dian Hong black tea were characterized by Curie-point pyrolysis–gas chromatography–mass spectroscopy (CP–Py–GC/MS). The ethyl-acetate extracts from both teas showed similar CP–Py–GC/MS results, with main pyrolytic products of carbon dioxide, caffeine, o-phenols, and phthalate esters. During pyrolysis, the n-butanol extract from Pu-erh tea formed carbon dioxide (38.92% of total pyrolytic products), alkaloids (49.7%), and nitrogen oxides (8.38%), as well as a small fraction of esters. The n-butanol extract from Dian Hong tea formed mainly alcohols, amines, esters, phenols, carboxylic acids, and alkaloids. The raw theabrownin extracts (ethanol precipitates) from the two teas produced substantially different CP–Py–GC/MS results. The raw theabrownin extract from Pu-erh tea formed mostly carbon dioxide during pyrolysis, whereas the counterpart extract from Dian Hong tea formed mainly carbon dioxide (48.23%) and nitrogen oxides (35.39%). The 3.5–100 kDa fractions separated from the theabrownin extracts of the two teas showed similar CP–Py–GC/MS results, whereas the fractions <3.5 kDa and >100 kDa formed substantially different pyrolytic products. These results showed that solvent extracts from Pu-erh tea and Dian Hong tea had substantially different chemical compositions and structures. The study suggested that CP–Py–GC/MS can be used to effectively identify chemical differences between tea extracts.     

Flame Retardant and Smoke Suppressant of Fe‐Organophilic Montmorillonite in Polyvinyl Chloride Nanocomposites

Two kinds of polyvinyl chloride (PVC)/organophilic montmorillonite (OMT) nanocomposites are prepared by a melt intercalation method. This study has been designed to determine if the presence of iron and zinc ions in the structure of montmorillonite (MMT) lattice can affect thermal, flame retardant and smoke suppressant properties. The information about the morphological structure of PVC/OMT nanocomposites was obtained using X-ray diffraction and transmission electron microscopy. The thermal and flame retardant properties of the nanocomposites were characterized by thermogravimetric analysis, limiting oxygen index and smoke density. The nanocomposites based on Fe-OMT exhibit better thermal, flame retardant properties and lower degradation degree than those of pure PVC. The degradation mechanism was studied by pyrolysis, gas chromatography and mass spectrometry (Py-GC-MS).     

Thermal degradation behaviors of epoxy resin/POSS hybrids and phosphorus–silicon synergism of flame retardancy

Epoxy resin (EP)/polyhedral oligomeric silsesquioxane (POSS) hybrids were prepared based on octavinyl polyhedral oligomeric silsesquioxane (OVPOSS) and phosphorus‐containing epoxy resin (PCEP). The PCEP was synthesized via the reaction between bisphenol A epoxy resin (DGEBA) and 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO). The structure and morphology of PCEP/OVPOSS hybrids were characterized by Fourier transform infrared spectroscopy and transmission electron microscopy. Differential scanning calorimetry revealed that the PCEP/OVPOSS hybrids possessed higher glass transition temperatures than that of PCEP. The thermal stability of the PCEP/OVPOSS hybrids was studied using thermogravimetric analysis (TGA). The TGA results illustrated the synergistic effect of phosphorus–silicon of flame retardancy: phosphorus promotes the char formation, and silicon protects the char from thermal degradation. The thermal degradation mechanism of the PCEP/OVPOSS hybrids was investigated by real time Fourier transform infrared spectra and pyrolysis/gas chromatogram/mass spectrometry (Py‐GC/MS) analysis. It was found that OVPOSS migrated to the surface of the matrix and then sublimed from the surface in nitrogen; whereas, the vinyl groups of OVPOSS were oxidated to form a radical trap which could react with pyrolysis radicals derived from PCEP to form the branched and crosslinked structure in air. The combustion behaviors of the hybrids were evaluated by micro combustion calorimetry. The addition of OVPOSS obviously decreased the value of peak heat release rate and total heat release of the hybrids. Moreover, scanning electron microscopy (SEM) and X‐ray photoelectron spectroscopy were used to explore the char residues of the PCEP and the hybrids. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 693–705, 2010     

Laccase‐catalyzed polymerization of lignocatechol and affinity on proteins of resulting polymers

For the synthesis of a new biologically functional polymer from a natural resource by an environment‐friendly method, the laccase‐catalyzed polymerization of a lignin‐based macromonomer, lignocatechol, was carried out for the first time in ethanol–phosphate buffer solvent system to give crosslinked polymers in good yields. Lignocatechol was prepared by the phase separation system of lignin and catechol in aqueous sulfuric acid. The copolymerization was also performed with urushiol to afford the corresponding copolymers in high yields. The polymerization mechanism was estimated by the IR and pyrolysis GC‐MS measurements, suggesting that the polymerization proceeded mainly at the catechol ring through a quinone radical intermediate. The thermal properties were measured by the DSC, TG, and TMA analyses, indicating that the polymers had high thermal stabilities because of the crosslinked structures. In addition, it was found that the resulting polymers had the affinity of bovine serum albumin (BSA) and glucoamylase. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 824–832, 2009