scholarly journals Identification and Evaluation of Hazardous Pyrolysates in Bio-Based Rigid Polyurethane-Polyisocyanurate Foam Smoke

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3205
Author(s):  
Sanita Reinerte ◽  
Vilhelmine Jurkjane ◽  
Ugis Cabulis ◽  
Arturs Viksna
Keyword(s):  
Thermal Degradation ◽  
Degradation Products ◽  
Hazard Analysis ◽  
Phenyl Isocyanate ◽  
Relative Content ◽  
Gas Chromatography Mass Spectrometry ◽  
Pyrolysis Gas ◽  
Gaseous Products ◽  
Two Samples ◽  
Index Value

In this study, rigid polyurethane (PU) and polyisocyanurate (PIR) foam samples made from renewable material (tall oil fatty acid) based polyols were analyzed by pyrolysis gas chromatography mass spectrometry (Py-GC/MS) to obtain information about the full relative smoke content, with a focus on substance identification by their functional groups and hazardousness. The relative content of gaseous products produced during the thermal degradation was evaluated between the two samples, differenced by their assigned isocyanate (NCO) index value—150 and 300. The main thermal degradation components of the rigid PU-PIR foam were found to originate from the decomposition of isocyanate, primarily forming 4,4′-methylenedianiline, 3,3′-diaminodiphenylmethane, N-methylaniline, aniline, 4-benzylaniline and phenyl isocyanate. Hazard analysis revealed that the most common hazards were the hazards related to health: H315 (36%), H319 (28%), H335 (25%), and H302 (23%). The chemical compound with the highest relative content value—4,4′-methylenedianiline (45.3% for PU and 52.4% for PIR)—was identified to be a suspected carcinogen and mutagen. The focus of the study was identifying and evaluating the relative quantities of the produced gaseous products, examine their hazardousness, and provide information on the released thermal degradation products to form a renewable-source based rigid PU and PIR foam.

scholarly journals Conversion Among Photo-Oxidative Products of Polypropylene in Solid, Liquid and Gaseous States

2020 ◽  
Author(s):  
Xuan Liu ◽  
Rui Yang
Keyword(s):  
Gas Chromatography ◽  
Solid State ◽  
Degradation Products ◽  
Gas Chromatography Mass Spectrometry ◽  
Pyrolysis Gas ◽  
Gaseous State ◽  
Gaseous Products ◽  
Oxidative Products ◽  
Solid Liquid ◽  
Oxidized Products

Abstract During aging of polymers, oxidized species on macromolecular chains in solid state, volatile degradation products in liquid state and gaseous degradation products in gaseous state are often investigated separately. The conversion among these products is not especially concerned and biased results may be obtained based on the products in a single state. In this paper, photo-oxidative products of commercial polypropylene (PP) and unstabilized PP in solid, liquid and gaseous states were investigated by using Fourier transform infrared spectroscopy (FTIR), pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and gas chromatography (GC). By comparing the formation profiles, conversion among the photo-oxidative products in three states was traced. During photo-oxidative aging, the main chains of PP were first oxidized to form carbonyl species in solid state, or fractured to form volatile alkenes as liquid. With the proceeding of aging, the oxidized main chains fractured to form small molecules, resulting in the conversion of oxidized species from solid state to liquid and gaseous states. When the aging degree was extremely high, the accumulation of liquid oxidized products was limited due to migration and condensation. Therefore, both the carbonyl index (CI) and the concentrations of volatile oxidized products were increased first and then decreased, while the concentrations of gaseous products kept increasing all along.

scholarly journals Thermal stability and gaseous exhaust products of bovine leather for firefighter boots

2019 ◽  
Vol 68 (1) ◽  
pp. 16-19
Author(s):  
Sandra Flinčec Grgac ◽  
Franka Žuvela Bošnjak ◽  
Boris Valečić ◽  
Jadranka Akalović
Keyword(s):  
Thermal Stability ◽  
Thermogravimetric Analysis ◽  
Fire Resistance ◽  
Direct Contact ◽  
Degradation Products ◽  
Flame Spreading ◽  
Gaseous Products ◽  
Heat Degradation ◽  
Two Samples ◽  
Artificial Surface

This paper aims to investigate fire resistance properties of two samples of fireproof bovine leather; both with smooth and perforated brushed surfaces. Apart from flammability and flame spreading, an important property is heat resistance and the development of gaseous products that occur during heat degradation. For the purpose of characterizing those properties, cowhide leather samples were exposed to thermogravimetric analysis (TGA) of monitoring gaseous degradation products (TG-IR) during decomposition. Considering the results of fire resistance, it can be concluded that tested samples of smooth bovine leather show satisfactory stability to the influence of flame and heat, while perforated brushed fireproof leather with artificial surface was partially pouched and gathered in the area of direct contact with flame. Both samples show similar behavior during TGA, but differences have been observed in the analysis of gaseous degradation products.

scholarly journals New Insights on Structures Forming the Lignin-Like Fractions of Ancestral Plants

2021 ◽  
Vol 12 ◽  
Author(s):  
Jorge Rencoret ◽  
Ana Gutiérrez ◽  
Gisela Marques ◽  
José C. del Río ◽  
Yuki Tobimatsu ◽  
...  
Keyword(s):  
Structural Information ◽  
2D Nmr ◽  
Plant Evolution ◽  
Pteridium Aquilinum ◽  
Gas Chromatography Mass Spectrometry ◽  
Aryl Ether ◽  
Pyrolysis Gas ◽  
Alkyl Aryl ◽  
Two Samples ◽  
G Ratio

In the present work, lignin-like fractions were isolated from several ancestral plants –including moss (Hypnum cupressiforme and Polytrichum commune), lycophyte (Selaginella kraussiana), horsetail (Equisetum palustre), fern (Nephrolepis cordifolia and Pteridium aquilinum), cycad (Cycas revoluta), and gnetophyte (Ephedra fragilis) species– and structurally characterized by pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) and two-dimensional nuclear magnetic resonance (2D-NMR) spectroscopy. Py-GC/MS yielded marker compounds characteristic of lignin units, except in the H. cupressiforme, P. commune and E. palustre “lignins,” where they were practically absent. Additional structural information on the other five samples was obtained from 2D-NMR experiments displaying intense correlations signals of guaiacyl (G) units in the fern and cycad lignins, along with smaller amounts of p-hydroxyphenyl (H) units. Interestingly, the lignins from the lycophyte S. kraussiana and the gnetophyte E. fragilis were not only composed of G- and H-lignin units but they also incorporated significant amounts of the syringyl (S) units characteristic of angiosperms, which appeared much later in plant evolution, most probably due to convergent evolution. The latter finding is also supported by the abundance of syringol derivatives after the Py-GC/MS analyses of these two samples. Regarding lignin structure, β−O−4′ alkyl-aryl ethers were the most abundant substructures, followed by condensed β−5′ phenylcoumarans and β−β′ resinols (and dibenzodioxocins in the fern and cycad lignins). The highest percentages of alkyl-aryl ether structures correlated with the higher S/G ratio in the S. Kraussiana and E. fragilis lignin-like fractions. More interestingly, apart from the typical monolignol-derived lignin units (H, G and S), other structures, assigned to flavonoid compounds never reported before in natural lignins (such as amentoflavone, apigenin, hypnogenol B, kaempferol, and naringenin), could also be identified in the HSQC spectra of all the lignin-like fractions analyzed. With this purpose, in vitro synthesized coniferyl-naringenin and coniferyl-apigenin dehydrogenation polymers were used as standards. These flavonoids were abundant in H. cupressiforme appearing as the only constituents of the moss lignin-like fraction (including 84% of dimeric hypnogenol B) and their abundance decreased in those of S. Kraussiana (with amentoflavone and naringenin representing 14% of the total aromatic units), and the two ancient gymnosperms (0.4–1.2%) and ferns (0–0.7%).

scholarly journals Enhancing the Phenolic Content of Bio-Oil by Acid Pre-Treatment of Biomass

2018 ◽  
Vol 7 (2) ◽  
pp. 163-169
Author(s):  
Nurgül Özbay ◽  
Elif Yaman
Keyword(s):  
Thermal Degradation ◽  
Phenolic Content ◽  
Degradation Products ◽  
Chemical Application ◽  
Pyrolysis Gas ◽  
Pine Wood ◽  
Wood Sawdust ◽  
Bio Oil ◽  
Pre Treatment ◽  
Pine Wood Sawdust

Pyrolysis of lignocellulosic biomass with acidic pre-treatment to produce valuable bio-chemicals has been carried out in an integrated pyrolysis-gas chromatograph/mass spectrometry system. Three different waste biomasses (fir wood sawdust, pine wood sawdust and nutshell) were subjected to acidic solution to specify the acid pre-treatment effect on biomass chemical structure, thermal degradation profile and pyrolysis products. Post acid pre-treatments, the changes in the biomasses and thermal degradation profile were studied through proximate, structure and ultimate analysis and thermogravimetric. The pre-treatment significantly reduced the inorganic, cellulose and hemicellulose content in biomass samples. According to the pyrolysis experiment results, acid pre-treatment provided the increasing of the amount of phenolic in the degradation products at 10 min pyrolysis time. All the results would assist further understanding of thermal decomposition and thermo-chemical application for bio-fuels and bio-chemicals of fir wood sawdust, pine wood sawdust and nutshell.Article History: Received January 15th 2018; Received in revised form May 24th 2018; Accepted 7th June 2018; Available onlineHow to Cite This Article: Ozbay, N. and Yaman, E (2018) Enhancing the Phenolic Content of Bio-Oil by Acid Pre-Treatment of Biomass. Int. Journal of Renewable Energy Development, 7(2), 163-169.https://doi.org/10.14710/ijred.7.2.163-169

scholarly journals Thermoanalytical studies (TG–DTG–DSC, Py–GC/MS) of sodium carboxymethyl starch with different degrees of substitution

2019 ◽  
Vol 138 (6) ◽  
pp. 4417-4425 ◽  
Author(s):  
Karolina Kaczmarska ◽  
Sylwia Żymankowska-Kumon ◽  
Łukasz Byczyński ◽  
Beata Grabowska ◽  
Artur Bobrowski ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Degradation Products ◽  
Qualitative Assessment ◽  
Gas Chromatography Mass Spectrometry ◽  
Pyrolysis Gas ◽  
Carboxymethyl Starch ◽  
Decomposition Processes ◽  
Starch Derivatives ◽  
Dsc Analyses ◽  
Sodium Carboxymethyl Starch

Abstract The paper presents the results of thermal analysis of polymer material in the form of starch derivatives in the form of sodium carboxymethyl starch (CMS–Na) with degree of substitution (DS) in the range 0.2–0.9 for the preparation of foundry binder. In this work, the thermal behavior of the modified starch and qualitative assessment of degradation products released during pyrolysis were determined and comprised. The analysis of the course of progressive decomposition of the starch material under controlled heating in the range of 25–1000 °C in anaerobic atmosphere was based on the results of thermal analysis methods (TG–DTG–DSC) in combination with the results of pyrolysis–gas chromatography–mass spectrometry (Py–GC/MS). The detailed TG–DTG–DSC analysis allowed to determine and compare the temperature at which the process of decomposition of carboxymethyl starches sodium salts with different degrees of substitution begins and to determine the course of its degradation under conditions corresponding to the contact of the foundry binder in the form of starch material with liquid metal (conditions like in foundry mold). Thermogravimetric analysis shows that decomposition processes are multistage, and dehydration is the first step of decomposition. Moreover, TG–DTG–DSC analyses indicate that the thermal stability and the decomposition path of tested compounds depend on the DS. Results of Py–GC/MS studies showed that the formation of decomposition products (including cyclic and aromatic hydrocarbons) in a predetermined temperature range is lower in the case of CMS–Na with high DS.

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