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1.
A new method for the determination of triphenyltin hydroxide using capillary column gas chromatography with a tin-selective flame photometric detector has been developed. Triphenyltin hydroxide and its potential metabolites are converted to methyl derivatives and separated on glass capillary columns coated with OV-101. Derivatization of triphenyltin hydroxide, triphenyltin chloride, diphenyltin dichloride, phenyltin trichloride, and bis-triphenyltin oxide is nearly quantitative with a minimum of redistribution products. The selectivity of the flame photometric detector is cearly demonstrated by the comparison of chromatographic profiles obtained from using both the flame photometric and flame ionization detectors. The use of this chromatographic system in the analysis of triphenyltin hydroxide in a fortified water sample demonstrates the potential use of this system in organotin residue chemistry. 相似文献
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New flame‐retardant epoxy resin compounds containing novolac derivatives with specific aromatic compounds have been developed. After crosslinking reactions between epoxy resin and hardener, the epoxy resin compounds formed highly flame‐retardant network structures that were obtained by including biphenylene and phenylene moieties in the main chains of novolac‐type epoxy resin and phenol novolac resin hardener. The high flame retardancy is due mainly to the stable foam layers that form during combustion because of the low elasticity at high temperatures and the high pyrolysis resistance of the compounds. Furthermore, the addition of excess phenol derivative hardener not only facilitates the formation of the foam layers by decreasing the crosslink densities but also reduces the amount of flammable substances generated from the epoxy resin compounds during combustion. The use of a multifunctional epoxy resin containing four glycidyloxy groups in the compounds improved characteristics such as heat resistance and strength at high temperatures, while maintaining excellent flame retardancy. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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L. K. Sal’keeva A. A. Bakibaev G. T. Khasenova Ye. K. Taishibekova L. M. Sugralina Ye. V. Minaeva A. K. Sal’keeva 《Russian Journal of Applied Chemistry》2016,89(1):132-139
The effect of bicyclic bisureas (glycolurils) and their derivatives functionalized with hydroxymethyl, halomethyl, and dimethoxyphoshorylmethyl groups on the flame resistance and physico-chemical properties of synthetic isoprene and divinyl rubbers was studied, and the procedures for preparing these agents were suggested. The rubbers with the addition of the synthesized bicyclic bisureas demonstrated satisfactory levels of flame resistance and physico-mechanical parameters. 相似文献
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Daewoong Kam Ketack Kim Hyun-Soo Kim Hua Kun Liu 《Electrochemistry communications》2009,11(8):1657-1660
Pyrazole derivatives are flame retardants and provide thermal protection on cathodes, as they help to form a thick protective film. A thicker film provides more protection and delays the thermal decomposition of the cathode. Among the tested pyrazoles, bis(trifluoromethyl)pyrazole (BFTMP) serves as the best flame retardant additive. Additionally, a cell with BFTMP shows better capacity retention than a cell with no additive in full-cell cycle life tests. 相似文献
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Analytical and environmental aspects of the flame retardant tetrabromobisphenol-A and its derivatives 总被引:2,自引:0,他引:2
Covaci A Voorspoels S Abdallah MA Geens T Harrad S Law RJ 《Journal of chromatography. A》2009,1216(3):346-363
The present article reviews the available literature on the analytical and environmental aspects of tetrabromobisphenol-A (TBBP-A), a currently intensively used brominated flame retardant (BFR). Analytical methods, including sample preparation, chromatographic separation, detection techniques, and quality control are discussed. An important recent development in the analysis of TBBP-A is the growing tendency for liquid chromatographic techniques. At the detection stage, mass-spectrometry is a well-established and reliable technology in the identification and quantification of TBBP-A. Although interlaboratory exercises for BFRs have grown in popularity in the last 10 years, only a few participating laboratories report concentrations for TBBP-A. Environmental levels of TBBP-A in abiotic and biotic matrices are low, probably due to the major use of TBBP-A as reactive FR. As a consequence, the expected human exposure is low. This is in agreement with the EU risk assessment that concluded that there is no risk for humans concerning TBBP-A exposure. Much less analytical and environmental information exists for the various groups of TBBP-A derivatives which are largely used as additive flame retardants. 相似文献
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Bile acids, such as cholic, chenodeoxycholic, deoxycholic, lithocholic and ursodeoxycholic acids, were allowed to react with hexafluoroisopropanol and tri-fluoracetic anhydride at 37 for 30 min. The resulting derivatives were gas chromatographed on QF-1, with flame ionization detection, and were identified by gas chromatography-mass spectrometry. Separation was good. By using this method, these acids were detected in samples of human duodenal fluid; the ratios of each were 24.4, 41.5, 24.9, 2.3 and 6.9%, respectively. 相似文献
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The effectiveness of a phosphoramidate tetraethyl piperazine‐1,4‐diyldiphosphoramidate (TEPP) as a flame retardant on cotton twill fabrics was compared with that of a previously studied diethyl 4‐methylpiperazin‐1‐ylphosphoramidate (DEPP). TEPP was formed in a reaction between two phosphonates and a piperazine then cotton twill fabrics were treated with TEPP at different levels of add‐on (2–19 wt%) and characterized using vertical flammability, limiting oxygen index, microscale combustion calorimetry, and thermogravimetric analysis methods. The results showed better flame retardancy and thermal behavior for TEPP fabrics when compared with DEPP fabrics. When the morphological structure of the formed char from the burned areas was examined by scanning electron microscopy, the results revealed a fairly insignificant difference in the mode of action between the two types of fabric. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
8.
Flammability and thermal degradation of flame retarded polypropylene composites containing melamine phosphate and pentaerythritol derivatives 总被引:7,自引:0,他引:7
The flammability of polypropylene (PP) composites containing intumescent flame retardant additives, i.e. melamine phosphate (MP) and pentaerythritol (PER), dipentaerythritol (DPER) or tripentaerythritol (TPER) was characterized by limiting oxygen index (LOI), UL 94 and the cone calorimeter, and the thermal degradation of the composites was studied using thermogravimetric analysis (TG) and real time Fourier transform infrared (RTFTIR). It has been found that the PP composite containing only MP does not show good flame retardancy even at 40% additive level. Compared with the PP/MP binary composite, the LOI values of the PP/MP/PER (PP/MP/DPER or PP/MP/TPER) ternary composites at the same additive loading are all increased, and UL 94 ratings of most ternary composites studied are raised to V-0 from no rating (PP/MP). The cone calorimeter results show that the heat release rate and smoke emission of some ternary composites decrease in comparison with the binary composite. It is noted from the TG data that initial decomposition temperatures of ternary composites are lower than that of the binary composite. The RTFTIR study indicates that the PP/IFR composites have higher thermal oxidative stability than the pure PP. 相似文献
9.
The extraction of chelate and ion-association complexes formed by various metal ions and two new organic reagents (derivatives of benzoxazolylacrolein) has been investigated in order to evaluate the possibilities for analytical application. The composition of the extracted species and their conditional extraction constants are given. Two simple extraction procedures for flame atomic absorption analysis of high purity lead salts have been developed. The proposed methods permit determination of (a) 1 × 10–5% Co, Fe and Ni and 5 × 10–6% Cu and Zn and (b) 1 × 10–5% Pd and 5 × 10–6% Ag and Au, with relative standard deviations in the range 4–8%. 相似文献
10.
Zhi Yong Wu Wei Xu Jin Kui Xia Yao Chi Liu Qian Xin Wu Wei Jian Xu 《中国化学快报》2008,19(2):241-244
An improved method for preparing melamine cyanurate (MCA) based flame retardant polyamide 6 (FRPA6) materials has been proposed. This processing method, i.e., improved in situ polymerization, was used to synthesize flame retardant PA6. In situ formed MCA nanoparticles were supposed to be linked to PA6 chains in the ε-caprolactam hydrolytic polymerization system to obtain startype polymers for the first time. Through TEM photographs, it can be found that the in situ formed MCA nanoparticles with diametric size of less than 50 nm, are nanoscaled, highly uniformly dispersed in the PA6 matrix. Synthesized flame retardant PA6 have good fire performance which can achieve UL-94 V-0 rating at 1.6 mm thickness with the presence of 7.34 wt.% MCA in the matrix. 相似文献
11.
Phytopharmaceuticals containing Valerian are used as mild sleep-inducing agents. The elemental composition of 3 different marks of Valeriana officinalis roots commercially available in the Argentinian market, their teas, and a commercial tincture have been studied. The content of Al, Ca, Cd, Co, Cr, Cu, Fe, Li, Mn, Ni, Pb, V, and Zn was determined in phytopharmaceuticals by flame atomic emission/absorption spectrometry, electrothermal atomic absorption spectrometry, and ultrasonic nebulization coupled to inductively coupled plasma-optical emission spectrometry. Prior to analyses of the samples, a digestion procedure was optimized. The analytical results obtained for Fe, Al, Ca, and V in the solid sample study were within the range 100-1000 mg/kg, and for Mn, Zn, and Pb within the range 10-100 mg/kg. Cadmium was found at levels up to 0.0125 mg/kg. 相似文献
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本文研究了以聚磷酸铵(APP)为主阻燃剂,次磷酸铝(AHP)和三聚氰胺氰尿酸盐(MCA)为辅阻燃剂的协效阻燃体系对聚丙烯(PP)阻燃性能的影响。 采用垂直燃烧测试、极限氧指数(LOI)测试、热重分析、锥形量热仪测试、扫描电子显微镜分析等技术手段对所制备的阻燃样品进行了阻燃性能分析。 结果表明:单独添加任一质量分数30%阻燃剂,均不能使PP获得良好的阻燃性能;当阻燃剂总质量分数保持在30%,m(APP):m(AHP):m(MCA)=4:1:1时获得理想阻燃效果,此时阻燃PP的LOI为33%,垂直燃烧测试达到V-0级,热释放速率峰值(PHRR)从765.7 kW/m2降为122.7 kW/m2。 相似文献
16.
The separation of a premixed air-acetylene flame is described. The interconal zone of this flame exhibits very low radiative background, and is only slightly cooler than that of a normal air-acetylene flame. The use of the separated flame in flame photometry, for which it has several pronounced advantages, has been investigated. 相似文献
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Stephens R 《Talanta》1973,20(8):765-773
A burner has been designed which provides an oxygen-shielded air-acetylene flame for atomic-absorption work. The chemical reducing properties of the oxygen-shielded flame operated under fuel-rich conditions are enhanced by the higher C: O ratio obtainable in the flame and by the higher flame temperature just above the reaction zone. The flame is inherently essentially free from the risk of flashback, and is offered as an alternative to the nitrous oxide-acetylene flame for use with certain types of equipment and for particular applications. 相似文献
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简单介绍了硅橡胶的阻燃和瓷化机理。依据阻燃剂、填料及炭层结构的不同,将硅橡胶分为阻燃和可瓷化两大类.综述了阻燃硅橡胶和可瓷化硅橡胶的阻燃性能和成炭结构的研究进展。分析表明:添加物理或化学膨胀型阻燃剂的硅橡胶,燃烧过程中形成的炭层疏松多孔,阻燃隔热性能优异,但炭层强度差;添加非膨胀型阻燃剂的硅橡胶,炭层结构相对密实,但表面不平整,存在孔洞和裂缝,阻燃效果不好;添加可瓷化填料的硅橡胶燃烧形成的陶瓷炭层坚硬而致密,具有优异的耐火持久性,但在隔绝热量方面不如膨胀炭层。炭层的疏松隔热与坚固耐久兼顾是阻燃硅橡胶未来可能的发展方向。 相似文献