Synthesis and performance of cyclic phosphorus-containing flame retardants

A series of organo-cyclic phosphorus compounds were synthesized in an attempt to find an efficient flame retardant (FR) for acrylonitrile-butadiene-styrene (ABS). The success of synthesis was confirmed by ¹H and ³¹P NMR. Thermogravimetric analysis (TGA) results reveal that cyclic phosphorus compounds synthesized in this study show almost one step degradation between 250 and 400 °C and are believed to work in the vapour phase rather than in the condensed phase. From UL-94 test, V-0 rating was achieved at 15-35 wt% loading of cyclic or cyclic alkyl phosphonate FR and no rating at 35 wt% loading of cyclic phosphate for ABS. On the other hand, a much lower loading (7.5%) was needed to obtain V-0 rating for polycarbonate when 3,9-diphenyl-3,9-dioxa-2,4,8,10-tetraoxa-3,9-diphosphaspiro-5,5-undecane (PBPP) was added as FR. All the results show that the flame retarding effect is strongly dependent on the P content of the FR incorporated. The flame retardant mechanism of cyclic phosphorus compounds is also discussed.     

磷酸酯阻燃剂HDP的合成工艺及其在ABS中的阻燃作用

采用新工艺路线合成高熔点磷酸酯阻燃剂———对苯二酚双(二苯基磷酸酯)(HDP).首先采用对苯二酚和三氯氧磷合成中间产物,再将中间产物与苯酚反应,经分离纯化得到产品HDP,收率达到90%以上,常温下为白色固体.采用傅里叶红外光谱、氢谱、磷谱和质谱测试确定了其结构.同时,研究了HDP的阻燃性,并与间苯二酚双(二苯基磷酸酯)(RDP)进行了比较,研究发现当HDP和RDP分别与成炭剂酚醛树脂(NP)按20/10比例添加到丙烯腈-丁二烯-苯乙烯(ABS)树脂中,增强了复合材料凝聚相阻燃作用,极限氧指数(LOI)有所提高.通过热重及锥形量热分析两种复合材料以及各种组分的热降解过程,阻燃剂的添加对ABS树脂的热稳定性和残炭量明显提高,而且ABS/HDP/NP复合材料的抑烟性更好;同时采用扫描电镜(SEM)和X射线能量色散谱(EDS),发现ABS/HDP/NP复合材料燃烧后成炭空隙均匀,其残炭中磷分布比ABS/RDP/NP复合材料残炭中的磷分布更加均匀.研究表明,HDP与NP互配添加到ABS中,在凝聚相阻燃作用优于RDP.     

The impact of resorcinol bis(diphenyl phosphate) and poly(phenylene ether) on flame retardancy of PC/PBT blends

Flame retardancy of bisphenol A polycarbonate (PC)/poly(butylene terephthalate) (PBT) blends was improved by the addition of resorcinol bis(diphenyl phosphate) (RDP) and poly(phenylene ether) (PPO). A PC/PBT blend at 70/30 weight ratio obtained a V‐0 rating by the addition of 10 wt% RDP and 10 wt% PPO. The combination of 5 wt% methyl methacrylate‐butadiene‐styrene tercopolymer (MBS) with 3 wt% ethylene‐butylacrylate‐glycidyl methacrylate tercopolymer (PTW) causes a remarkable increase in toughness of the PC/PBT/RDP blend while maintaining a high rigidity. A detailed investigation of the flame‐retardant action of PC/PBT/RDP and PC/PBT/RDP/PPO blends was performed using thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), TGA‐FTIR, temperature‐programmed pyrolysis/gas chromatography/mass spectrometry (TPPy/GC/MS), and scanning electron microscopy/energy dispersive spectrometer (SEM/EDS). The results demonstrate that RDP induces a higher char yield at ca. 450 °C and synchronously increases the thermal stability of the blend with PPO. The flame‐retardant role of RDP in the condensed phase was discerned from TGA, FTIR, and SEM/EDS of the residues. Copyright © 2010 John Wiley & Sons, Ltd.     

Thermal behavior of poly(bisphenol A carbonate) in the presence of phosphorus compounds

To clarify the interaction between poly(bisphenol A carbonate) (PBAC) and phosphorus compounds such as triphenylphosphine oxide (TPPO), triphenyl phosphate (TPP), and resorcinol bis(diphenyl phosphate) (RDP), PBAC was heated in the presence of these phosphorus compounds at 240 °C for 2 h, and the resulting polymers were analyzed by ¹H NMR spectroscopy and gel permeation chromatography. When heated in the presence of TPPO, the PBAC sample decomposed extensively, resulting in a substantial decrease in molecular weight. On the other hand, thermal treatment in the presence of the phosphates increased the molecular weight. In both cases the molecular weight distribution became narrower. Thermal treatment of PBAC in the presence of both TPPO and TPP allowed us to control the molecular weight with a narrower distribution. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1069–1074, 2004     

Synthesis and applications of biscyclic phosphorus flame retardants

The influence of structural effects of organo-phosphorus flame retardants (FRs) on their flame retardant action was investigated. A series of spirobisphosphorus compounds including 3,9-dibutyl-3,9-dioxo-2,4,8,10-tetraoxa-3,9-diphosphaspiro-5,5-undecane were prepared using various synthetic methods such as the Arbuzov reaction. The chemical structure of the product was confirmed by ¹H and ³¹P NMR. Thermogravimetric analysis (TGA) results reveal that these cyclic phosphorus compounds show a single step degradation in the range of 250-400 °C and act in the gas phase rather than in the condensed phase. The obtained products were blended with an acrylonitrile-butadiene-styrene copolymer (ABS) or polycarbonate (PC) and their flame retardant behavior was evaluated using a UL-94 vertical test. V-0 ratings are achieved at 15-35 wt% loading of FR for ABS and at a much lesser amount of loading for PC. In both cases, it is apparent that the flame retardancy is strongly dependent on the P content of the flame retardant.     

Fire retardancy mechanisms of arylphosphates in polycarbonate (PC) and PC/acrylonitrile-butadiene-styrene

The pyrolysis of polycarbonate (PC) and PC/acrylonitrile-butadiene-styrene (PC/ABS) with and without arylphosphates (triphenylphosphate TPP, resorcinol-bis(diphenyl phosphate) RDP and bisphenol A bis(diphenyl phosphate) BDP) is investigated by thermal analysis as key to understanding the flame retardancy mechanisms and corresponding structure–property relationships. The correspondence between the decomposition temperature range of arylphosphates and PC is pointed out as prerequisite for the occurrence of the reaction between arylphosphate and structures that are typical for the beginning of PC decomposition. Resulting cross-linking enhances charring in the condensed phase and competes with the alternative release of phosphate in the gas phase and thus flame inhibition. Flame inhibition was identified as the main flame retardancy mechanism. The additional condensed phase mechanisms optimise the performance.     

碳酸钙晶须合成过程中可溶性磷酸盐的作用机理研究

以可溶性磷酸盐为控制剂,一步碳化法制备了文石相碳酸钙晶须。借助于XRD和FTIR,分析了可溶性磷酸盐在碳酸钙晶须合成过程中的作用机理。研究结果表明：通入CO₂进行碳化反应前,可溶性磷酸盐与Ca(OH)₂反应生成了热力学上最稳定的磷酸钙化合物——羟基磷灰石;在通入CO₂初期,[CO₃^2-(OH)]进入到羟基磷灰石的晶格,部分替代[PO₄^3-],生成碳酸羟基磷灰石,然后以此为结晶中心诱导文石相的异相成核,Ca²⁺、CO₃^2-不断叠加,进而生长为碳酸钙晶须。     

Mechanisms of phosphate transfer on the purine salvage pathway

Abstract

α-D-Ribofuranosyl-1,2-cyclic monophosphate and 5-phospho-α-D-ribofuranosy1-1, 2-cyclic monophosphate were synthesized in good yields. The five-membered ring cyclic phosphates have ³¹p chemical shifts similar to those found for such structures, presumably reflecting the smaller O-P-O bond angle, compared to that in six-membered ring phosphates. The rate of OH^? catalyzed ring opening was similar to that reported for ethylene phosphate, indicating relief of ring strain during hydrolysis. α-D-Ribofuranosyl-1, 2-cyclic monophosphate was found to irreversibly inactivate purine nucleoside phosphorylase (EC 2.4.2.1) at its catalytic center.     

Aluminum phosphate modified brucite and its flame retardant and smoke suppression performance on ethylene‐vinyl acetate resin

A novel halogen‐free flame retardant (FR) consisting of brucite, aluminum phosphate (AlP), and silane coupling agent (B/AlP/A) was prepared via co‐precipitation assembly technique. The morphology, chemical compositions, size distribution, and thermal stability of B/AlP/A were investigated. When used in ethylene‐vinyl acetate (EVA) resin, the B/AlP/A could significantly enhance the flame retardant and smoke suppression performance of the EVA composites, which is mainly attributed to the AIP. With 50 wt% FR loading, the peak heat release rate (PHRR) of EVA‐B/AlP/A (299.2 kW · m^?2) is much lower than that of EVA‐B/A (387.4 kW · m^?2). Moreover, B/AlP/A shows an excellent smoke suppression performance. For example, the smoke production rate is 0.017 m² · g^?1 that has been decreased by 72.1%, compared with B/A. The improvement arises from the amorphous AlP layer on brucite, which helps to create a firm and porous protective char layers on the burning EVA composites. Meanwhile, better mechanical property could be simultaneously obtained with the large FR amount. The fluffy surface of B/AlP/A has good compatibility with EVA and tangle more polymer chains, enhancing the mechanical properties. In a word, this simple and convenient method could pave the way for developing a more efficient and cost‐effective brucite‐based FR.     

用于磷酸酯和甲基膦酸酯类化合物测定的固相微萃取新型涂层

以羟基硅油和二乙烯基苯为涂层材料 ,采用溶胶 凝胶技术和自由基引发交联的方法制备了一种新型的固相微萃取探头。采用顶空固相微萃取与气相色谱联用的方法模拟检测了水中磷酸酯和甲基磷酸酯类化合物。与商品化固相微萃取探头相比 ,该新型涂层可获得高的萃取效率。甲基膦酸二甲酯、磷酸三甲酯和磷酸三丁酯的最低检测限分别为 0 34,2 2 0和 0 0 1mg/L,相对标准偏差为 3 6 7%～ 6 4 4 % ,线性范围为 1～ 2个数量级 ,方法重现性好 ,回收率为 89 4 6 %～ 90 88%。     

聚苯基磷酸间苯二酚酯的合成、表征及热性能

采用熔融聚合法, 以间苯二酚、 三氯氧磷和苯酚为原料, 通过两步合成, 制备了阻燃剂聚苯基磷酸间苯二酚酯(PRPP). 用红外光谱(FTIR)、 ¹H, ¹³C和³¹P核磁共振(NMR)、 凝胶色谱(GPC)及热重分析(TGA)等对聚合物的结构、 分子量、 热性能进行了表征. 结果表明, PRPP具有与液态商品间苯二酚双(二苯基)磷酸酯(RDP)相同的组成单元, 其数均分子量为3227, 分子量分布系数M_w/M_n=1.31, 聚合度n≈12; PRPP的起始分解温度与液态RDP相同, 但在高温下PRPP的热稳定性优于RDP, 其分解50%质量的温度提高了235 ℃, 在高温阶段表现出优良的成炭性能.     

Comparative studies on radiolytic degradation of deuterium labeled and unlabeled tributyl phosphates

Deuterium labeled tributyl phosphates were synthesized and their solutions in n-dodecane have been investigated for γ-radiolytic degradation up to an absorbed dose of 2,000 kGy from a ⁶⁰Co source. The performance was compared with undeuterated TBP. Radiolysis extent and pattern of formation of major degradation products, viz. dibutyl hydrogen phosphate and monobutyl dihydrogen phosphate were found to be very similar from deuterated or undeuterated samples. Extraction behavior for UO₂ ²⁺ and Pu(IV) was studied after the radiolysis, and the results showed similarity in extraction/stripping behavior for all labeled or unlabeled TBP samples. The isotope effect (k _H/k _D) observed is minimal in this γ-radiolytic degradation study.     

Theoretical evaluation of the substrate-assisted catalysis mechanism for the hydrolysis of phosphate monoester dianions

Quantum chemistry methods coupled with a continuum solvation model have been applied to evaluate the substrate-assisted catalysis (SAC) mechanism recently proposed for the hydrolysis of phosphate monoester dianions. The SAC mechanism, in which a proton from the nucleophile is transferred to a nonbridging phosphoryl oxygen atom of the substrate prior to attack, has been proposed in opposition to the widely accepted mechanism of direct nucleophilic reaction. We have assessed the SAC proposal for the hydrolysis of three representative phosphate monoester dianions (2,4-dinitrophenyl phosphate, phenyl phosphate, and methyl phosphate) by considering the reactivity of the hydroxide ion toward the phosphorus center of the corresponding singly protonated monoesters. The reliability of the calculations was verified by comparing the calculated and the observed values of the activation free energies for the analogous S_N2(P) reactions of F⁻ with the monoanion of the monoester 2,4-dinitrophenyl phosphate and its diester analogue, methyl 2,4-dinitrophenyl phosphate. It was found that the orientation of the phosphate hydrogen atom has important implications with regard to the nature of the transition state. Hard nucleophiles such as OH⁻ and F⁻ can attack the phosphorus atom of a singly protonated phosphate monoester only if the phosphate hydrogen atom is oriented toward the leaving-group oxygen atom. As a result of this proton orientation, the SAC mechanism in solution is characterized by a small Brønsted coefficient value (β_lg=−0.25). This mechanism is unlikely to apply to aryl phosphates, but becomes a likely possibility for alkyl phosphate esters. If oxyanionic nucleophiles of pK_a<11 are involved, as in alkaline phosphatase, then the S_N2(P) reaction may proceed with the phosphate hydrogen atom oriented toward the nucleophile. In this situation, a large negative value of β_lg (−0.95) is predicted for the substrate-assisted catalysis mechanism.     

2,4-Dinitrophenol as an activating reagent in a facile preparation of cyclic phosphate triesters

2,4-Dinitrophenol was employed with benzyloxy-bis-(diisopropylamino)phosphine to synthesise the cyclic phosphate derivatives of a series of alkane diols (HO-(CH₂)_n-OH, n=2-6) in good isolated yields. Tetrazole and DNP were compared by ³¹P NMR spectroscopy for their ability to catalyse the cyclisation at the P(III) stage. Investigation of the phosphate triester stability under various oxidation and chromatographic conditions resulted in the optimisation of the isolation procedures of the chemically unstable cyclic compounds. Conditions for debenzylation were developed to yield the corresponding cyclic phosphodiesters quantitatively. The methodology was further applied to the preparation and isolation of the cyclic phosphate derivative of a carbohydrate.     

Selectivity issues in targeted metabolomics: Separation of phosphorylated carbohydrate isomers by mixed-mode hydrophilic interaction/weak anion exchange chromatography

Phosphorylated carbohydrates are important intracellular metabolites and thus of prime interest in metabolomics research. Complications in their analysis arise from the existence of structural isomers that do have similar fragmentation patterns in MS/MS and are hard to resolve chromatographically. Herein, we present selective methods for the liquid chromatographic separation of sugar phosphates, such as hexose and pentose phosphates, 2‐ and 3‐phosphoglycerate, dihydroxyacetone phosphate and glyceraldehyde 3‐phosphate, as well as glucosamine 1‐ and 6‐phosphate utilizing mixed‐mode chromatography with reversed‐phase/weak anion‐exchangers and a charged aerosol detector. The best results were obtained when the reversed‐phase/weak anion‐exchanger column was operated under hydrophilic interaction liquid chromatography elution conditions. The effects of various chromatographic parameters were examined and are discussed on the basis of a simple stoichiometric displacement model for explaining ion‐exchange processes. Employed acidic conditions have led to the complete separation of α‐ and β‐anomers of glucose 6‐phosphate at low temperature. The anomers coeluted in a single peak at elevated temperatures (>40°C) (peak coalescence), while at intermediate temperatures on‐column interconversion with a plateau in‐between resolved anomer peaks was observed with apparent reaction rate constants between 0.1 and 27.8×10^?4 s^?1. Dynamic HPLC under specified conditions enabled to investigate mutarotation of phosphorylated carbohydrates, their interconversion kinetics, and energy barriers for interconversion. A complex mixture of six hexose phosphate structural isomers could be resolved almost completely.     

Effect of poly(bisphenol A acryloxyethyl phosphate) on the activation energy in thermal degradation of urethane acrylate

Poly(bisphenol A acryloxyethyl phosphate) (BPAAEP) was blended in different ratios with a commercial urethane acrylate to obtain a series of UV curable flame-retardant resins. The thermal oxidative degradation mechanism of their cured films in air were studied by thermogravimetric analysis at several heating rates between 5 and 20°C min⁻¹. The activation energies were determined using Kissinger method, Friedman method, Flynn-Wall method, Horowitz-Metzger method and Ozawa method. The results showed that the activation energies of the blends were lower than that of pure urethane acrylate at lower degree of degradation, whereas the higher activation energies were obtained at higher degree of degradation.     

Solid-state NMR on thermal and fire residues of bisphenol A polycarbonate/silicone acrylate rubber/bisphenol A bis(diphenyl-phosphate)/(PC/SiR/BDP) and PC/SiR/BDP/zinc borate (PC/SiR/BDP/ZnB) - Part I: PC charring and the impact of BDP and ZnB

Structural changes in the condensed phase of bisphenol A polycarbonate (containing 0.45 wt% poly(tetrafluoroethylene))/silicone acrylate rubber/bisphenol A bis(diphenyl-phosphate) (PC/SiR/BDP) and PC/SiR/BDP/zinc borate (PC/SiR/BDP/ZnB) during thermal treatment in nitrogen atmosphere and in fire residues were investigated by solid-state NMR. ¹H, ¹¹B, ¹³C and ³¹P NMR experiments using direct excitation with a single pulse and ¹H-³¹P cross-polarization (CP) were carried out including ³¹P{¹H} and ¹³C{³¹P}double-resonance techniques (REDOR: Rotational Echo Double Resonance) on a series of heat-treated samples (580 K-850 K). Because many amorphous phases occur in the solid residues, and solid-state NMR spectroscopy addresses the most important sites carbon, phosphorus and boron, this paper is the key analytical approach for understanding the pyrolysis and flame retarding phenomenon in the condensed phase of PC/SiR/BDP and PC/SiR/BDP/ZnB.For the system PC/SiR/BDP it is shown that (i) at temperatures around 750-770 K (main decomposition step) carbonaceous charring of PC occurs and arylphosphate structures are still present, reacted in part with the decomposing PC; (ii) for higher temperatures from 770 K the phosphorus remaining in the solid phase increasingly converts to amorphous phosphonates and inorganic orthophosphates with a minor amount of crystalline orthophosphates; and (iii) ¹H-³¹P{¹H} CP REDOR and ¹H-¹³C{³¹P} CP REDOR NMR experiments suggest that the phosphates and phosphonates are bound via oxygen to aromatic carbons, indicating the interaction with the carbonaceous char.When ZnB is added to the system PC/SiR/BDP, (i) ZnB leads to a slightly enhanced PC decomposition for temperatures below 750 K; (ii) α-Zn₃(PO₄)₂ and borophosphate (BPO₄) are formed in small amounts at high temperatures suggesting a reaction between BDP and ZnB during thermal decomposition; and (iii) most of the borate remains in the solid residues, forming an amorphous pure borate network, with the BO₃/BO₄ ratio increasing with higher temperatures.The NMR data of thermal and fire residues are highly correlated, underlining the importance of this work for understanding the pyrolysis and flame retardancy mechanisms in the condensed phase during the burning of the PC/SiR blends.     

Study on syntheses of phosphates and transition‐metal complexes on viscose rayon felt for flame retardancy

High‐performance materials for flameproofing, phosphates (polyphosphate and ammonium phosphate) were synthesized on viscose rayon felt. This surface reaction has the advantage of a nonblooming effect and an application in thermosetting plastics. Metal complexes have the effect of reducing the amount of smoke. Therefore, in the second step, transition‐metal complexes were synthesized on the viscose rayon ammonium phosphate felt. This article focuses on the surface modification of phosphates and metal complexes on viscose rayon. All reactions were confirmed by attenuated total reflectance Fourier transform infrared and time‐of‐flight secondary ion mass spectrometry. As the concentrations of phosphoric acid and urea increased, the peak intensities of ammonium ion groups and phosphate groups greatly increased. The thermal properties of the synthesized materials were studied with thermogravimetric analysis and oxygen index testing. On the basis of the experimental results, the synthesized flame‐retardancy materials showed excellent physicochemical and thermal effects and flame retardancy. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2815–2823, 2000     

Effect of surfactants on phase,crystal growth and photocatalysis of calcium stannate synthesized by cyclic microwave and calcination combination

Calcium stannate (CaSnO₃) was successfully synthesized in the solutions containing different surfactants by cyclic microwave and calcination combination. Phase, morphology and vibration mode were characterized by X-ray diffraction, field emission scanning electron microscopy and Fourier transform infrared spectroscopy. Growth mechanism of the products was also explained according to the analytical results. Their photocatalytic activities were tested through methylene blue (MB) degradation induced by UV radiation. In the MB solution with pH 6, the S-CTAB product showed the highest decolorization efficiency of 89.1% and the highest rate constant of 4.374?×?10^?3 min^?1.     

Enthalpie de formation de la whitlockite Ca18Mg2H2(PO4)14

Pure and well crystallised whitlockite Ca₁₈Mg₂H₂(PO₄)₁₄ has been synthesized by precipitation from the magnesium and calcium nitrates and the diammonic phosphate. The product of the reaction has been characterized by X-ray diffraction, IR spectroscopy and chemical analysis. Using differential conduction calorimeters the enthalpies of solution of the whitlockite and of a mixture of the solid reactants - the tricalcium, the trimagnesium and the dicalcium phosphates - have been measured at 25°C for various concentrations of solid in a 46 wt% nitric acid solution. A combination of the enthalpies of solution with the enthalpies of formation of the reactants allows us to determine the standard enthalpy of formation of the whitlockite. The value deduced, -27,93·10³kJ mol^-1, is compared to the standard enthalpies of formation of the trimagnesium and the tricalcium phosphates. This revised version was published online in August 2006 with corrections to the Cover Date.