Study of the thermal decomposition of flame-retarded unsaturated polyester resins by thermogravimetric analysis and Py-GC/MS

The thermal degradation behaviours of flame-retarded unsaturated polyester resin formulations containing ammonium polyphosphate (APP), Cloisite 25A nanoclay and zinc based smoke suppressants have been studied using thermogravimetric analysis (TGA) combined with infrared analysis of the evolved gases (EGA) and pyrolysis/gas chromatography-mass spectrometry (GC/MS). In TGA-EGA experiments, the mass loss as a function of temperature has been correlated with the evolution of carbon monoxide (CO) and carbon dioxide (CO₂) and oxygen (O₂) consumption as measured by an oxygen analyser. The effect of APP, Cloisite 25A and the smoke suppressants on the evolution of CO and CO₂ has been examined. The decomposition behaviour of flame-retarded polyester resins under isothermal pyrolytic conditions was investigated and the evolved gaseous products were collected and qualitatively and semi-quantitatively analysed via GC/MS. The addition of APP does not yield many new gaseous products relative to the unmodified polyester resin neither does the presence of zinc borate (ZB) and zinc stannate (ZS) together with APP. Possible chemical interactions are discussed in an attempt to explain the observed results.     

A 3D Hybrid Praseodymium–Antimony–Oxochloride Compound: Single‐Crystal‐to‐Single‐Crystal Transformation and Photocatalytic Properties

A 3D organic–inorganic hybrid compound, (2‐MepyH)₃ [{Fe(1,10‐phen)₃}₃][{Pr₄Sb₁₂O₁₈(OH) Cl_11.5}(TDC)_4.5({Pr₄Sb₁₂O₁₈(OH)Cl_9.5} Cl)] ? 3 (2‐Mepy) ? 28 H₂O ( 1 ; 2‐Mepy=2‐methylpyridine, 1,10‐phen=1,10‐phenanthroline, H₂TDC=thiophene‐2,5‐dicarboxylic acid), was hydrothermally synthesized and structurally characterized. Unusually, two kinds of high‐nuclearity clusters, namely [(Pr₄Sb₁₂O₁₈ (OH)Cl₁₁)(COO)₅]^5? and [(Pr₄Sb₁₂O₁₈ (OH)Cl₉)Cl(COO)₅]^4?, coexist in the structure of compound 1 ; two of the latter clusters are doubly bridged by two μ₂‐Cl^? moieties to form a new centrosymmetric dimeric cluster. An unprecedented spontaneous and reversible single‐crystal‐to‐single‐crystal transformation was observed, which simultaneously involved a notable organic‐ligand movement between the metal ions and an alteration of the bridging ion in the dimeric cluster, induced by guest‐release/re‐adsorption, thereby giving rise to the interconversion between compound 1 and the compound (2‐MepyH)₃[{Fe(1,10‐phen)₃}₃][{Pr₄Sb₁₂O₁₈(OH)Cl_11.5}(TDC)₄({Pr₄Sb₁₂O₁₈Cl_10.5(TDC)_0.5(H₂O)_1.5}O_0.5)] ? 25 H₂O ( 1′ ). The mechanism of this transformation has also been discussed in great detail. Photocatalytic H₂‐evolution activity was observed for compound 1′ under UV light with Pt as a co‐catalyst and MeOH as a sacrificial electron donor.     

Synthesis and thermal decomposition of antimony(III) oxide hydroxide nitrate

The thermal decomposition of the only known antimony nitrate antimony(III) oxide hydroxide nitrate Sb₄O₄(OH)₂(NO₃)₂, whose synthesis routes were reviewed and optimized was followed by TG-DTA under an argon flow, from room temperature up to 750°C. Chemical analysis (for hydrogen and nitrogen) performed on samples treated at different temperatures showed that an amorphous oxide hydroxide nitrate appeared first at 175°C, and decomposed into an amorphous oxide nitrate above 500°C. Above 700°C, Sb₆O₁₃ and traces of -Sb₂O₄ crystallized.Author to whom all correspondence should be addressed     

Study of Sb‐doped SnO2 Gray Ceramic Pigment with Cassiterite Structure

In this study, Sb_xSn_1?xO₂ (0 ≤ x ≤ 0.5) compositions were synthesized by the ceramic method from Sb₂O₃‐SnO₂ and Sb₂O₅‐SnO₂ mixtures and characterized by Differential thermal analysis (DTA) and thermogravimetric analysis (TG), X‐ray diffraction, UV‐V‐NIR spectroscopy and CIE L*a*b* (Commission Internationale de l'Eclairage L*a*b*) parameters measurements. Solid solutions with cassiterite structure were obtained at 1300 °C. These solid solutions are stable into glazes. From Sb₂O₃, light gray coloured materials were obtained. From Sb₂O₅, bluish gray coloured materials were obtained at 1300 °C/6h when x ≥ 0.3. Sb_xSn_1?xO₂ with 0.3 ≤ x < 0.5, T = 1300 °C and Sb₂O₅ might be established as compositional range, fired temperature and antimony precursor to obtain gray ceramic pigments in this system.     

Thermal degradation of fire retardant chloroparaffin-metal compound mixtures—Part I: Antimony oxide

The main characteristics of the evolution of HCl and SbCl₃ during the thermal degradation of chloroparaffin-Sb₂O₃ mixtures, which are typical fire retardant additives for polymers, have been studied.Sb₂O₃ reacts with HCl evolved from the chloroparaffin without any apparent effect on the dehydrochlorination process itself. Evolution of SbCl₃ occurs at a maximum rate between 300 and 350°C and is somewhat delayed in the earlier stage of reaction, depending on the composition of the mixture.     

Über hexagonale Perowskite mit Kationenfehlstellen. XXX. 5 L-Stapelvarianten in den Systemen BaO?Re2O7?Sb2O5 und BaO?WO3?Sb2O5

On Hexagonal Perovskites with Cationic Vacancies. XXX. 5 L Stacking Polytypes in the Systems BaO — Re₂O₇? Sb₂O₅ and BaO? WO₃? Sb₂O₅ In the systems BaO? Re₂O₇? Sb₂O₅ and BaO? WO₃? Sb₂O₅ phases of composition Ba₅BaRe Sb□O_15?x□_x (x = 0 up to x ? 3/4) and Ba₅BaWSb□O_15?x/2□_x/2 (x ? 3/2 up to x ? 2) are existent, which have an orthorhombic distorted 5 L structure. The pure Sb compound has to be formulated as Ba₃BaSb₂O₉ and crystallize in an orthorhombic variant of the hexagonal BaTiO₃ type.     

Synthesis and Structural Characterization of a Novel Type of Heteropolyanion: [Sb4Mo12(OH)6O48]10‐

A novel antimony substituted polyoxomolybdate has been synthesized and characterized by X‐ray structure analysis, energy dispersive X‐ray fluorescence analysis, Raman and IR spectroscopy. The [Sb₄Mo₁₂(OH)₆O₄₈]^10‐ anion exhibits a central Sb₄(OH)₆O₁₄ core where all Sb^V atoms are coordinated octahedrally by six oxygen atoms. It represents a novel type of heteropolyanion with no known analogous structure in literature.     

Microwave assisted hydrothermal synthesis of zinc hydroxystannate films on glass substrates

Zinc stannate (ZnSnO₃, Zn₂SnO₄) and its precursor, i.e. zinc hydroxystannate (ZnSn(OH)₆), have emerged as technological nanomaterials for different applications. Herein, we report synthesis of polycrystalline zinc hydroxystannate (ZHS) film on glass substrate through facile and efficient microwave assisted hydrothermal growth. The method comprises of three steps; deposition of ZnO seed films on glass substrates through spray pyrolysis, growth of ZnO nanorod arrays over the seeded substrates through microwave assisted hydrothermal method and transformation of the as-synthesized ZnO nanorod arrays into the ZHS films through microwave treatment in aqueous precursor solution of SnCl₄ and NaOH. The films were characterized by energy dispersive X-ray spectroscopy, X-ray diffraction and scanning electron microscopy (SEM). The films contain two crystalline phases namely ZnO with [002] as preferred growth direction and ZnSn(OH)₆ preferably grown along [200] vector. The obtained ZHS films consist of crystals of exclusively cubic structure with sizes up to several microns. Microwave irradiation time, NaOH/SnCl₄ molar ratio, concentration of Sn⁴⁺ ions, and the applied power are the four parameters which influence the size, aerial density and growth rate of ZHS microblocks.     

Characterization of Sb2O3 subjected to different ion and plasma surface treatments

This paper presents a study of Sb₂O₃ subjected to oxygen plasma and to ion beam bombardment (Ar⁺ and O₂⁺ ions of 4 keV) by x‐ray photoelectron and reflected electron energy‐loss spectroscopies. Changes in stoichiometry (i.e O/Sb ratio) and oxidation state of Sb have been detected and correlated with the chemical and ballistic effects of the beams used for alteration of the Sb₂O₃ surface. Thus, oxygen plasma treatments lead to a significant oxidation of the surface layers of this material with the formation of up to 51% Sb⁵⁺ species as found by Sb 4d curve‐fitting analysis. By contrast, O₂⁺ ion bombardment only produces a mild oxidation of the target with the formation of ～13% Sb⁵⁺ species. Argon ion bombardment induces a complex process where Sb⁵⁺ and Sb⁰ species are formed simultaneously. This result has been discussed in terms of a disproportionation reaction of the type Sb³⁺ → Sb⁵⁺ + Sb⁰. The changes in the electronic properties of the treated material are consistent with the loss upon oxidation to Sb⁵⁺ of the valence states associated to the 5s² electron pair of antimony. Approximate shapes of valence bands for Sb₂O₃ and Sb₂O₅ pure compounds have been extracted by applying factor analysis to valence band spectra of Sb₂O₃ subjected to different ion and plasma treatments. Copyright © 2003 John Wiley & Sons, Ltd.     

Thermal Study of the Ceramic Pigments CoxZn(7−x)Sb2O12

Using the Pechini method, pigments with spinel structure (Zn₇Sb₂O₁₂)were synthesized by substitution of the cation Zn²⁺ by Co²⁺, in compounds with different concentrations of Sb₂O₃. The doping resulted in Co_xZn_(7–x)Sb₂O₁₂ phases(x=1–7) that were isomorphs to spinel, denominated as samples A and B. After thermal treatment at 400°C for 1 h, the powders were characterized by thermogravimetry(TG) and differential thermal analysis (DTA). The results indicate a different behavior whena higher amount of Sb₂O₃ is used, due to the presence of a secondary phase (ilmenite). This revised version was published online in July 2006 with corrections to the Cover Date.     

Effect of CeO<Subscript>2</Subscript> and Sb<Subscript>2</Subscript>O<Subscript>3</Subscript> on the phase transformation and optical properties of photostable titanium dioxide

In the present work, the effect of individual additives calculated as molar fractions of Sb₂O₃ and CeO₂ (x _{Sb 2}O₃ range: 0.03–0.08 %, x _{CeO 2} range: 0.05–0.14 %), on the phase composition, phase transformation, and optical properties of photostable rutile titanium dioxide was studied using selective leaching method, ICP-AES technique, XRD method, spectrophotometric analysis and S _BET measurements. The starting material was hydrated titanium dioxide. It was observed that the addition of Sb₂O₃ to TiO₂ did not influence the anatase-rutile phase transformation, but increasing the CeO₂ addition caused a decrease in the rutilization degree. Thus, CeO₂ acted as an inhibitor of the TiO₂ phase transformation. Sb₂O₃ addition to TiO₂ presumably caused the formation of a co-phase of Sb with Ti. Cerium formed a separate phase, CeO₂, and reacted partly with titanium, probably creating co-phase, Ce_0.8Ti_0.2O₂. Comparing the colour of modified rutile titanium dioxide according to the type of the additive introduced, it was found that TiO₂ with CeO₂ had higher brightness but lower white tone values when compared with TiO₂ modified with Sb₂O₃. The relative lightening power and grey tone of the modified TiO₂ were higher in TiO₂ modified with Sb₂O₃. The values of the photocatalytic activity measured in all TiO₂ samples modified either with Sb₂O₃ or CeO₂ were very similar and varied around the value of 21.     

Antimony oxide–PVC synergism: Laser pyrolysis studies of the interaction mechanism

Laser-probe pyrolysis is used to investigate the synergistic flame-retardancy effect observed for antimony oxide (Sb₂O₃)–PVC combinations. Molecular beam-mass analysis detection techniques permit direct sampling of the laser-vaporized species without the need for intermediate product collection stages. Laser pyrolysis of a PVC formulation containing 3 phr Sb₂O₃ provides the first direct evidence for the production of volatile SbCl₃ during thermal decomposition. Selective laser irradiation of PVC in the presence of unheated Sb₂O₃ in the sample cell reveals that HCl evolved from the polymer substrate rapidly reacts with Sb₂O₃(s) to form the volatile flame-retardant species SbCl₃. Similar results are observed for SbOCl(s). These reactions are distinct from those previously proposed, which involve the formation and subsequent thermal decomposition of intermediate solid-phase antimony oxychlorides, and demonstrate that the antimony compounds, rather than serving only as inert sources for SbCl₃, readily participate in direct chemical reactions with HCl. In addition to the composition of the reaction products, information is also obtained on their evolution characteristics from the sample cell.     

微波加热液相均匀沉淀法制备纳米Sb2O3阻燃剂(英)

Antimonyoxide(Sb2O3)isanimportantadditiveflameretardant.Itisextensivelyusedinflameretar鄄danttreatmentofpolyolefine,polyvinylchloride,polyesterandtextiles.TheefficiencyofhalogenatedflameretardantcanbeenhancedbycooperatingwithSb2O3.ThesizeofSb2O3hasgreatef…     

Hydrothermal synthesis of antimony oxychloride and oxide nanocrystals: Sb4O5Cl2, Sb8O11Cl2, and Sb2O3

We described herein a facile solution-phase route to three nanocrystals of antimony oxychlorides and oxides (Sb₄O₅Cl₂, Sb₈O₁₁Cl₂, and Sb₂O₃), whose morphologies and phases were varied with the pH value of a reaction mixture or composition of a mixed solvent. In particular, the solvent composition controlled the selective preparation of cubic Sb₂O₃ (senarmontite) and orthorhombic Sb₂O₃ (valentinite). Both cubic and orthorhombic Sb₂O₃ samples exhibited strong emission properties.     

Composition and Crystal Structure of SmSb2O4Cl Revisited – and the Analogy of Sm1.5Sb1.5O4Br

The quaternary halide‐containing samarium(III) oxidoantimonates(III) Sm_1.3Sb_1.7O₄Cl and Sm_1.5Sb_1.5O₄Br were synthesized through solid‐state reactions from the binary components (Sm₂O₃, Sb₂O₃ and SmX₃, X = Cl and Br) at 750 °C in evacuated fused silica ampoules. They crystallize tetragonally in the space group P4/mmm, like the basically isotypic bismuthate(III) compounds SmBi₂O₄Cl and SmBi₂O₄Br, but show larger molar volumes and therefore contradict an ideal composition of “SmSb₂O₄X” (X = Cl and Br). Both single‐crystal X‐ray diffraction and quantitative electron‐beam microprobe analysis revealed the actual compositions of the investigated antimony(III) compounds, which can be understood as heavily Sm³⁺‐doped derivatives of “SmSb₂O₄X” hosts at the Sb³⁺ site. (Sm1)³⁺ is coordinated eightfold by oxygen atoms in the shape of a cube. The mixed‐occupied (Sb/Sm2)³⁺ cation has four oxygen atoms and four halide anions as neighbors forming a square antiprism. The oxygen atoms and anions establish alternating layers parallel to the ab‐plane, which alternate when stacked along [001].     

Diorganotin(IV) complexes of dideprotonated pyridoxine (PN, vitamin B6). The crystal structures of [SnEt2(PN-2H)] · CH3OH, [SnEt2(PN-2H)(DMSO)] and [SnBu2(PN-2H)]

The reactions of dimethyl-, diethyl- and dibutyltin(IV) oxides with pyridoxine (PN) in toluene/ethanol led to the formation of compounds [SnR₂(PN-2H)] which were characterized by EI and FAB mass spectrometry and by IR, Raman, Mössbauer and ¹H, ¹³C and ¹¹⁹Sn NMR spectroscopy. The structures of [SnEt₂(PN-2H)] · CH₃OH, [SnBu₂(PN-2H)] and [SnEt₂(PN-2H)(DMSO)] were determined by X-ray diffractometry. The first two contain dimeric [SnR₂(PN-2H)]₂ units in which two bridging-chelating pyridoxinate anions link the Sn atoms, while in [SnEt₂(PN-2H)(DMSO)] the DMSO coordinates to the tin atom via its O atom in a similar dimeric unit.     

The structure of thorikosite,a naturally occurring member of the bismuth oxyhalide group

Thorikosite, (Pb₃Sb_0.6As_0.4)(O₃0H)Cl₂, is a naturally occurring member of the bismuth oxyhalide group isostructural with LiBi₃O₄Cl₂. The space group isI4/mmm witha = 3.919(1)A?,c = 12.854(5)A?, andZ = 1. A crystal structure analysis showed complete solid solution of Pb²⁺, Sb³⁺, and As³⁺ on the single cation site and large atomic temperature factors indicative of pervasive structural disorder. The latter is due to the structural adjustments necessary to accommodate cations of very different sizes in the same site. Thorikosite is closely related to synthetic tetragonal PbSbO₂Cl through the coupled substitution Sb³⁺O^2? ? Pb²⁺(OH)^?.     

Aging effects on fire-retardant additives in polymers

Extensive thermal aging experiments have been conducted on (i) ethylene-propylene rubber (EPR) formulations containing various commercial halogenated-hydrocarbon fire-retardant additives together with Sb₂O₃, and (ii) on chlorosulfonated polyethylene (CSPE) formulations with and without added Sb₂O₃. Significant losses of both chlorine and antimony are found on aging, dependent upon the ability of the particular halocarbon to undergo intramolecular dehydrohalogenation. The stoichiometry indicates antimony volatilization as SbCl₃. Arrhenius treatment of the data for the EPR formulation which undergoes the most rapid loss gives an overall activation energy of 34 kcal/mol for antimony volatilization and indicates that fire-retardant loss should become appreciable only at temperatures significantly above ambient (i.e., 70°C). Oxygen index flammability measurements showed moderately increased flammability for certain aged EPR samples, but showed significantly decreased flammability for aged CSPE which was correlated with the loss of other volatile components from the formulation.     

Characterization of fire retardant polymer blends by temperature resolved in-source pyrolysis mass spectrometry

The characterization of fire retardant polymer blends by temperature resolved in-source pyrolysis mass spectrometry (PYMS) is demonstrated with a few examples. Electron impact (EI) and electron capture negative ionization (ECNI) were used to identify the thermal degradation products of polymer blends containing brominated fire retardants. PYMS (EI mode) offers an analytical instrument for a fast analysis of unknown mixtures of polymers and for the presence of fire retardant additives. Under electron impact conditions, in vacuo, low-molecular weight additives like fire retardants mainly evaporate from the polymer matrix. PYMS (EI mode) has been used for the characterization of addition polymers like polystyrene and acrylonitrile-butadiene-styrene copolymer, and for condensation polymers like the polyester poly(butylene terephthalate). Applying electron capture negative ionization, at low argon pressure in the ionization chamber, a more realistic pyrolysis situation is created because the premature loss of volatile additives is suppressed. The selectivity of ECNI for electron accepting groups like bromine makes it possible to study the influence of brominated compounds on the degradation processes in the melt. This is demonstrated by our studies on polystyrene and acrylonitrile-butadiene-styrene copolymer. High-molecular weight pyrolysis products in the m/z range of 1000 - 2000 are detected for p-bromopolystyrene and for a blend of high impact polystyrene with the fire retardant system decabromodiphenyl ether/antimony(III) oxide. In addition to the formation of antimony bromides shown in earlier studies, the emission of the synergist antimony(III) oxide as a dimeric cluster (Sb₄O₆) or as a reduced Sb₄ cluster is observed under PYMS conditions.