An efficient flame retardant for epoxy resin: Preparation and pyrolytic behaviour

2018 ◽  
Vol 31 (9-10) ◽  
pp. 1009-1019 ◽  
Author(s):  
Baoping Yang ◽  
Xiang Li ◽  
Lurong Wang ◽  
Yabin Zhang ◽  
Jinfeng Cui ◽  
...  
Keyword(s):  
Flame Retardant ◽  
Epoxy Resin ◽  
Flame Retardancy ◽  
High Efficiency ◽  
Mass Spectrometry Analysis ◽  
Gas Chromatography Mass Spectrometry ◽  
Test Results ◽  
Pyrolysis Gas ◽  
Spectrometry Analysis ◽  
Combined Test

Using 4,4-diaminodiphenyl methane as a curing agent, three kinds of monomers, 4,4′-dihydroxybenzophenone, diphenyl chlorophosphite and 1,4-phenylene diisocyanate (NCO), were introduced into a thermosetting resin (DGEBA). The flame retardancy properties of the composites were studied, and the results were compared with those of 5 wt% bis(bis(4-((diphenoxyphosphoryl)oxy)phenyl)methyl) 1,4-phenylenedicarbamate (DHPP-OH-NCO), 10 wt% DHPP-OH-NCO and 15 wt% DHPP-OH-NCO curing agents. The results showed that 15 wt% DHPP-OH-NCO had an improved flame retardancy, the limited oxygen index reached 33.5% and the vertical burning test (UL94) achieved a V-0 level. A cone calorimeter experiment showed that the addition of the flame retardant significantly reduced the amount of generated smoke and heat. Macroscopic digital images, scanning electron microscopy images and thermogravimetric analysis results further revealed that the epoxy resin (EP) with DHPP-OH-NCO exhibited greater char yields. The flame retardancy mechanism of the flame retardant was preliminarily shown by pyrolysis–gas chromatography–mass spectrometry analysis. The combined test results demonstrate that a high-efficiency phosphorous-containing flame retardant for EPs was successfully developed.

A transparent and intumescent phosphaphenanthrene/phenylpyrazole-containing epoxy resin system and its flame retardancy

2021 ◽  
pp. 095400832199241
Author(s):  
Zijin Luo ◽  
Zhe Chen ◽  
Jun Wei ◽  
Dongchao Wang ◽  
Han Chen ◽  
...  
Keyword(s):  
Flame Retardant ◽  
Epoxy Resin ◽  
Flame Retardancy ◽  
Gas Chromatography Mass Spectrometry ◽  
Control Group ◽  
Pyrolysis Gas ◽  
Limiting Oxygen Index ◽  
Cone Calorimeter Test ◽  
Epoxy Resin System ◽  
Index Value

A novel intumescent flame retardant, PPMD, was designed from phosphaphenanthrene and nitrogen heterocycles through the two-step gut reactions of 1,4-phthalaldehyde and 3-methyl-1-phe-nylpyrazol-5-ylamine. After determination of its structure by nuclear magnetic resonance and Fourier-transform infrared analyses, PPMD was added to an epoxy resin (EP) to facilitate a curing process. Thus, EP/PPMD samples with excellent transparency and flame retardancy were acquired. For example, the EP sample satisfied the UL-94 V-0 standard and achieved a limiting oxygen index value of 30.5% because of the incorporation of 5 wt% PPMD. The cone calorimeter test of the EP/5% PPMD sample revealed that its total smoke production (TSP) and total heat release (THR) values of EP/5% PPMD was only 22.5% and 56.4% of the control group, respectively. Moreover, the average effective heat of combustion (av-EHC) value of EP/5% PPMD was reduced by 34.1%, indicating that PPMD possessed high flame-inhibition activity and smoke suppression efficiency. The flame-retardant mechanisms of PPMD were also investigated in gas phase by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and in condensed phase by XPS and IR.

scholarly journals Biodegradation and metabolic pathway of fenvalerate by Citrobacter freundii CD-9

AMB Express ◽  
2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jie Tang ◽  
Dan Lei ◽  
Min Wu ◽  
Qiong Hu ◽  
Qing Zhang
Keyword(s):  
Environmental Pollution ◽  
Environmental Remediation ◽  
High Efficiency ◽  
Mass Spectrometry Analysis ◽  
Gas Chromatography Mass Spectrometry ◽  
Citrobacter Freundii ◽  
16S Rrna Sequence ◽  
Intracellular Enzyme ◽  
Pyrethroid Insecticides ◽  
Spectrometry Analysis

Abstract Fenvalerate is a pyrethroid insecticide with rapid action, strong targeting, broad spectrum, and high efficiency. However, continued use of fenvalerate has resulted in its widespread presence as a pollutant in surface streams and soils, causing serious environmental pollution. Pesticide residues in the soil are closely related to food safety, yet little is known regarding the kinetics and metabolic behaviors of fenvalerate. In this study, a fenvalerate-degrading microbial strain, CD-9, isolated from factory sludge, was identified as Citrobacter freundii based on morphological, physio-biochemical, and 16S rRNA sequence analysis. Response surface methodology analysis showed that the optimum conditions for fenvalerate degradation by CD-9 were pH 6.3, substrate concentration 77 mg/L, and inoculum amount 6% (v/v). Under these conditions, approximately 88% of fenvalerate present was degraded within 72 h of culture. Based on high-performance liquid chromatography and gas chromatography-mass spectrometry analysis, ten metabolites were confirmed after the degradation of fenvalerate by strain CD-9. Among them, o-phthalaldehyde is a new metabolite for fenvalerate degradation. Based on the identified metabolites, a possible degradation pathway of fenvalerate by C. freundii CD-9 was proposed. Furthermore, the enzyme localization method was used to study CD-9 bacteria and determine that its degrading enzyme is an intracellular enzyme. The degradation rate of fenvalerate by a crude enzyme solution for over 30 min was 73.87%. These results showed that strain CD-9 may be a suitable organism to eliminate environmental pollution by pyrethroid insecticides and provide a future reference for the preparation of microbial degradation agents and environmental remediation.

TMAH-pyrolysis – gas chromatography – mass spectrometry analysis of residual lignin changes in softwood kraft pulp during oxygen delignification

2004 ◽  
Vol 82 (7) ◽  
pp. 1197-1202 ◽  
Author(s):  
Shiyu Fu ◽  
Lucian A Lucia
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Mass Spectrometry Analysis ◽  
Gas Chromatography Mass Spectrometry ◽  
Residual Lignin ◽  
Oxygen Delignification ◽  
Pyrolysis Gas ◽  
Spectrometry Analysis ◽  
Pyrolysis Gas Chromatography ◽  
Chromatography Mass Spectrometry

The residual lignins from pulps and effluent lignins from oxygen delignification effluents were characterized using pyrolysis – gas chromatography – mass spectrometry in the presence of tetramethylammonium hydroxide. The results indicated that oxidation under alkali oxygen conditions can induce fragmentation in lignin and produce more acid groups, but the lignin maintains most of its C6–C3 units. Oxygen delignification also led to a decrease in diphenyl structures in the residual lignin and an enrichment in concentration of lignin carbohydrate complex structures.Key words: residual lignin, pyrolysis, oxygen delignification.

Investigation of nickel ammonia phosphate with different morphologies as a new high-efficiency flame retardant for epoxy resin

2019 ◽  
Vol 32 (4) ◽  
pp. 359-370 ◽  
Author(s):  
Weiwei Zhang ◽  
Hongjuan Wu ◽  
Weihua Meng ◽  
Jiahe Li ◽  
Yumeng Cui ◽  
...  
Keyword(s):  
Flame Retardant ◽  
Epoxy Resin ◽  
Flame Retardancy ◽  
Photoelectron Spectroscopy ◽  
High Efficiency ◽  
Ammonium Phosphate ◽  
Cone Calorimetry ◽  
Limiting Oxygen Index ◽  
X Ray ◽  
The Matrix

Nanowires, nanosheets, and microflowers of nickel ammonium phosphate (NiNH4PO4·H2O) were synthesized by a mixed solvothermal method and used to improve the flame retardancy of epoxy resin (EP). The solvent concentration and surfactant content were found to play a key role in nucleation and growth of NiNH4PO4·H2O. The structure of NiNH4PO4·H2O was characterized by X-ray diffraction and X-ray photoelectron spectroscopy. The flame retardancy, thermostability, mechanical properties, and flame retardancy mechanism of EP/NiNH4PO4·H2O composites were analyzed using the limiting oxygen index (LOI), cone calorimetry (Cone), mechanical property tests, thermogravimetric analysis, and thermogravimetric–Fourier transform infrared spectroscopy. The results indicated that NiNH4PO4·H2O has proper thermal stability and greatly improves the flame retardancy of EP. The nanosheets outperformed the other morphologies; the EP/5% NiNH4PO4·H2O nanosheets have an LOI of 35.2%, which exceeds that of pure EP (24.7%). Furthermore, Cone showed that these nanosheets have the lowest peak heat release rate and peak smoke production rate, which are 69.1% and 36.5% lower than those of pure EP, respectively. NiNH4PO4·H2O can promote the formation of a stable char layer and release nonflammable gases, thus protecting the matrix by preventing heat and oxygen transfer and reducing the concentration of combustible gas. NiNH4PO4·H2O is expected to serve as a new high-efficiency flame retardant for EP.

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