Thermal decomposition of organic derivatives of crystalline zirconium phosphate

Organic derivatives ofγ-zirconium phosphate were investigated. Then- alkanol derivatives lost their crystal and structural water in several steps. The thermal stability of the molecules increased with increasing number of carbon atoms in the alkyl chain. The investigated materials are less stable thanα-zirconium phosphate derivatives.     

层状α-氢型磷酸氢锆混合二氧化硅的交流电导

1 引言无定形和多晶粉末层状α-水合磷酸氢锆是一种固体质子电解质.多晶粉末层状α-水合磷酸氢锆的电导率随结晶度的提高而明显降低,但是其电导表观活化能相同而和结晶度无关.电导主要是由质子沿着微晶的水合表面迁移所致.因此,增大水合表面有可能提高多晶粉末层状α-磷酸氢锆的电导率.α-磷酸氢锆的层状结构由层间的磷氧基形成氢键     

Thermal decomposition of organic derivatives of crystalline zirconium phosphate

The diethylene glycol, benzyl alcohol and benzylamine derivatives of- and-zirconium phosphates were prepared and their thermal behaviour was investigated by means of differential thermal analysis. In all cases, the derivatives of-zirconium phosphate were more stable than those of-zirconium phosphate.

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Zusammenfassung Es wurden Diethylenglykol-, Benzylalkohol- und Benzylamin-Derivate von- und-Zirkoniumphosphaten hergestellt und ihr Thermisches Verhalten mittels DTA untersucht. In allen Fällen waren die Derivate der-Zirkoniumphosphate stabiler als die der-Zirkoniumphosphate.

     

Preparation of hybrid film of polyaniline and organically pillared zirconium phosphate nanosheet by electrodeposition

α-Zirconium phosphate was chemically modified with 1,2-bis(dimethylchlorosilyl)ethane to graft organic chain, and then it was used as host material for inorganic nanosheet-polyaniline hybrid. The grafted α-zirconium phosphate was exfoliated in an acetonitrile solution with tetrabutylammonium salt and aniline. The electrodeposition in the presence of aniline was performed, and then it resulted in a formation of higher-order structure in which phosphate nanosheet was propped up by 1,2-bis(dimethylchlorosilyl)ethane with intrusion of polyaniline into the nanospace. The gravimetric capacitance of the α-zirconium phosphate without grafts and polyaniline hybrid film was around 194 F/g with the base on the amount of polyaniline mass. On the other hand, the α-zirconium phosphate nanosheet with grafts and polyaniline hybrid film provided larger capacitance of around 350 F/g in maximum. The nanospace formed by grafted phosphate nanosheet with 1,2-bis(dimethylchlorosilyl)ethane molecules gives increased amounts of polyaniline included and diffusion paths for ions.     

ESCA investigations of amorphous and crystalline zirconium acid phosphates

Amorphous and micro-crystalline α- and γ-zirconium acid phosphates have been investigated by the ESCA technique. α-zirconium phosphate has been also studied as a single crystal. Both the B.E. of zirconium and phosphorous electrons in zirconium phosphates are slightly higher than those reported for zirconium derivatives and trivalent metal phosphates, indicating a stronger polarization of the ZrO and PO bonds. Furthermore, it seems that some ESCA features of the zirconium phosphates investigated are structure dependent. However, no definitive conclusions have been drawn because of the lack of knowledge of the “charging-up” phenomena in protonic conductors such as zirconium phosphates. Satellite structures have been observed in the P_2s, P_2p, Zr_3d and Zr_4p regions. The position and the intensity of these “shake-up” effects are again dependent on the nature of the examined phase and they seem to be due to the presence of electron defect structures induced by X-rays or already present in the original samples.     

Thermal behavior of zinc γ-zirconium phosphate intercalation compounds

Summary The layered ion-exchangers γ-zirconium phosphate and γ-zirconium phosphate containing intercalated diamines, obtained by exchanging zinc ions, have been synthesized and characterized. Zinc ions are able to form coordination compounds between the layers of the host matrix and consequently form zinc complexes formed in situ. The zinc ions uptake, the thermal behavior and the structural characterization of the compounds obtained have also been examined. The thermal stability and X-ray spectra of these compounds depend on the type of isomeric diamine precursor. The zinc fully exchanged γ-zirconium phosphate is able to form ZnS particles in the host matrix. The X-ray spectra of this obtained material matched those of the initial γ-zirconium phosphate precursor.     

Thermal decomposition of organic derivatives of crystalline zirconium phosphate-phosphite

Organic derivatives of crystalline zirconium phosphate-phosphite (ZrPP) are easily obtained by direct contact of the given organic solution with the crystalline material. The thermal decomposition of benzyl alcohol, benzylamine and some other aromatic compounds intercalated in ZrPP was examined. All examined samples lose their crystal water first at a relatively low temperature. The structural water is lost at a relatively higher temperature (in comparison with the crystalline-zirconium phosphate derivatives).

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Zusammenfassung Organische Derivate von kristallinem Zirkoniumphosphatphosphit (ZrPP) werden durch direkten Kontakt der kristallinen Substanz mit der gegebenen organischen Lösung problemlos erhalten. Es wurde die thermische Zersetzung von in ZrPP eingelagertem Benzylalkohol, Benzylamin und einiger anderer aromatischer Verbindungen untersucht. Alle untersuchten Proben geben zuerst bei relativ niedrigen Temperaturen ihr Kristallwasser ab. Strukturelles Wasser wird (im Vergleich zu kristallinem-Zirkoniumphosphat) bei relativ höheren Temperaturen abgegeben.

     

Study of natural and ion exchanged vermiculite by emanation thermal analysis,TG, DTA and XRD

Emanation thermal analysis (ETA), thermogravimetry, DTA and XRD were used in thermal characterization of natural vermiculite (Santa Olalla, Huelva, Spain) and of Na^+- and - exchanged vermiculite samples during heating in air in the range 25-1100°C. A good agreement between the results of these methods was found. Changes in the radon release rate measured by ETA, which reflected the decrease and collapse of the interlayer space after the release of water as well as the formation of new crystalline phases were evaluated using a mathematical model. The model used for the evaluation was found suitable for the quantitative characterization of microstructure changes during in situ conditions of heating of vermiculite samples. This revised version was published online in July 2006 with corrections to the Cover Date.     

Kinetic study of the dehydration of modified Y zeolites

The dehydration of ferric exchanged Y zeolites is studied by thermal analysis. Their DTA shows three endotherms in the temperature range 80–450°C. The order of reaction and apparent energies of activation are calculated using various equations. The order of dehydration is nearly one and the apparent energy of activation is 4–8 kcal mole^?1. The effect of heating rate is studied. The energy of activation as determined by the Kissinger and Ozawa method is about 12 kcal mole^?1, which is comparable with the heat of adsorption of water determined by the gravimetric method, and is more acceptable.     

Preparation and properties of poly(vinyl alcohol)/exfoliated α-zirconium phosphate nanocomposite films

In this work, poly(vinylalcohol)(PVA)/exfoliated α-zirconium phosphate(e-α-ZrP) nanocomposites of various compositions were created by a solution casting method. The α-ZrP compound was synthesized by refluxing. The characteristic properties of the PVA/e-α-ZrP composite films were examined by thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and tensile tests. Tensile tests indicated that with the loading of e-α-ZrP, the tensile strength and the elongation at break were increased by 17.3% and 26.6% compared to neat PVA, respectively. It is noteworthy that optimum film properties were obtained with 0.8 wt% e-α-ZrP, and higher proportions of e-α-ZrP, may be related to the aggregation of e-α-ZrP particles and deterioration of the film properties. On the whole, the nanocomposite PVA/e-α-ZrP systems had mechanical and thermal properties which were superior to that of the neat polymer and its conventionally filled composites.     

α-三氢化铝的热分解动力学

用差热分析(DTA)研究了a-三氢化铝在氦气流下的热分解动力学。建立了A-E方程中动力学参数与DTA曲线的特征温度之间的关系式, 用序贯法对竞争模型进行最佳判别和参数估算, 确定a-三氢化铝的热分解曲线可用方程[-In(1-x)]~(1/4)=r_0e~(-E/RT_t)来描述, 表观活化能E为121.4±6.3 kJmoL~(-1), 指前因子r_0为8.1×10~(11±1)(sec-1), 模型计算结果与实验结果吻合较好。     

Preparation and structure of n-alkyl ester derivatives of zirconium bis (monohydrogen orthophosphate) dihydrate with a layer structure

Zirconium bis (monohydrogen orthophosphate) dihydrate with a layer structure, called γ-zirconium phosphate, has been heated with phosphoric acid esters of n-alkyl alcohols [n-C_nH_2n+1OPO₃H₂ (n = 1 ∼ 18)] under reflux in a mixture of water and acetone. Half of the interlayer monohydrogen orthophosphate groups are exchanged with a phosphate esters. Only monoesters are involved in the exchange even though mixtures of mono- and di-esters are used for the reflux. X-Ray and electron microscope examinations show that the layer framework of γ-zirconium phosphate is unchanged during the reaction, while the basal spacing (d₀₀₁) increases with increasing number (n) of carbon atoms in the alkyl chain of the phosphate ester. The plot of d₀₀₁ vs n consists of two linear relations the slopes of which are 2.43 and 1.42 Å/carbon atoms for n ⩽ 4 and n ⩾5, respectively. When the obtained compounds are swelled with n-alkyl alcohols having the same lengths of alkyl chains as those of exchanged phosphate esters, the basal spacing increases linearly with a single slope 2.43 Å/carbon atom. The change in slope is attributed to the change in the arrangement of alkyl chains between the phosphate layers and discussed in comparison with the structure of a polyethylene crystal.     

Epoxy-nanocomposites containing exfoliated zirconium phosphate: Preparation via cationic photopolymerisation and physicochemical characterisation

Gels of exfoliated α-zirconium phosphate in 3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexane carboxylate (hereafter BCDE) were polymerised by a UV-induced process and the resulting nanocomposites were characterised by TEM, X-ray diffraction, thermogravimetric analysis and dynamic-mechanical thermal analysis. Real-time FT-IR spectroscopy was used to investigate the photopolymerisation kinetics. The polymerisation rate of the gels is faster than that of neat BCDE, especially when the filler is functionalised with aminoalcohols (HO(CH₂)_nNH₂, with n = 3, 4, 5). The composites exhibit lower T_g values in comparison with neat polymerised BCDE. Because of the barrier effect towards oxygen diffusion due to the high aspect ratio of the filler particles, all composites also exhibit enhanced thermal stability.     

Determination des Transitions Vitreuses et Locales de PMMA/Al2O3 Par des Methodes Thermiques et Chromatographiques

Differential thermal analysis (DTA) technique was used to determine the glass transition temperatures of polymethyl methacrylate (PMMA). When PMMA was adsorbed on α-alumina, DTA could not use to obtain the glass transition temperatures of the system PMMA/α-Al₂O₃. Inverse gas chromatography at infinite dilution proved to be an excellent technique to highlight glass transitions and local transitions of PMMA adsorbed on α-Al₂O₃, at various covered surface fractions.     

Tris-(8-hydroxy-quinoline) aluminium/zirconium phosphate: a novel hybrid assembly with strong luminescence and prolonged lifetime

A novel hybrid assembly of tris-(8-hydroxy-quinoline) aluminium intercalated into modified α-zirconium phosphate in aqueous media was fabricated successfully, resulting in the dramatically enhanced greenish-blue-light emission and prolonged excited-state lifetime.     

氧离子导体La2Mo2O9中α→β相变非等温动力学的研究

以差热分析(differential thermal analysis,DTA)为手段研究了La2Mo2O9中α→β相变的非等温动力学。采用Flynn-Wall-Ozawa法计算了不同转化分数下的相变活化能E,并用Ozawa迭代法对E值进行了修正。应用Criado-Ortega法获得了α-La2Mo2O9→β-La2Mo2O9相变各温度区间的动力学机理函数,并用譒atava-譒esták法进行了验证。结果表明:La2Mo2O9中α→β相变的表观活化能与转化分数有关,说明该相变不属于一步简单反应。不同温度区间α→β相变的动力学机理函数不同,836～840K、842～848 K和850～853 K的动力学机理函数G(x)可依次表示为:-ln(1-x)、[-ln(1-x)]2/3、[-ln(1-x)]3/4。     

铬酸铵钠复盐结晶的热分解

采用TG-DTG、DTA和XRD对铬酸铵钠复盐结晶(NaNH4CrO4•2H2O)的热分解过程进行研究,结果表明NaNH4CrO4•2H2O的热分解过程分为三步进行,第一步是在50～95 ℃温度范围结晶水的脱除,第二步是在100～180 ℃的温度范围铵的初步热分解,产物为铬酸钠和重铬酸铵,第三步是215～385 ℃进行的铵的完全分解.存在生成重铬酸钠与生成三氧化二铬的竞争反应.在氨不易扩散的条件下,最终分解产物为三氧化二铬、重铬酸钠和铬酸钠的混合物;在流动气氛中,400～790 ℃温度范围,NaNH4CrO4•2H2O热分解产物为重铬酸钠.与传统的铬酸钠硫酸酸化生产重铬酸钠工艺相比,该方法无副产物产生,是一清洁工艺.     

TG and DTA Study of the Thermal Dehydration of Metal-exchanged Zeolite-4A Samples

Zeolite-4A is a hydrated aluminosilicate which becomes more hydrated when exchanged with transition metals. In this work, the dehydration kinetics of cobalt, nickel and copper(II)-exchanged zeolite-4A were studied by means of TG and DTA over the temperature range from 20 to 500°C, and the numbers of water molecules in the metal-exchanged zeolite samples were calculated. It was observed that, as the ionic radius of the hydrated metal increased, the number of water molecules also increased. The loss of water from the zeolite samples generally occurred in the temperature range 100–300°C and was manifested in the DTA graphs by an extended endothermic effect. The DTA curves demonstrated that the peak position shifted towards lower temperatures as the metal concentration increased or, in other words, the water of hydration increased. The kinetic parameters (order of reaction and activation energy) were calculated via the Coats and Redfern method. The process of dehydration was found to follow first-order kinetics. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effect of chemical structure and thermal history on the β transition of polystyrene and some substituted polystyrenes

DTA (differential thermal analysis) traces for various kinds of polystyrene and substituted polystyrenes, including bulk-polymerized, monodisperse, and isotactic samples, have been recorded below the glass temperature. It has been shown that the β transition is dependent upon polymer structural modification, traces of water or solvent, and sample thermal history. The experimental data presented here support the conclusion that the β transition is due to conformational changes involving backbone motions and phenyl ring reorientation.     

Sn0.5Ti((0.5)O2固溶体的溶胶-凝胶法制备、表征及其热稳定性研究

采用溶胶-凝胶法制备了Sn_0.5Ti_0.5O₂固溶体.用X射线衍射(XRD)、差热分析(DTA)和红外(IR)技术对材料的结构和热稳定性进行了分析表征.固溶体的热稳定性与起始反应温度有关,在40℃水浴温度下制备的凝胶经1000℃烧结,发生了相分解,出现了富Sn和富Ti相,而在80℃水浴温度下制备的凝胶经1200℃烧结也不发生相分解,仍以Sn_0.5Ti_0.5O₂相存在,而且用差热分析也得到了同样的结论.