The synthesis and thermal behaviour of zinc diphosphates

Zinc diphosphates (Zn₂P₂O₇ · 5H₂O, Zn₂P₂O₇ · 3H₂O, 5K_1.4Zn_1.3P₂O₇ · 16H₂O, and 5K_0.8Zn_1.6P₂O₇ · 9H₂O) were made by the wet process. The composition of the products was dependent on the conditions (concentration, pH, and dropping rate of the solution) of the process. When the products were heated, decomposition of the diphosphates to orthophosphate took place below about 150 ·C. Polymerization of the phosphates to phosphates with longer chains was observed in the temperature range 150 to 400 ° C. The amorphous phosphates thermally produced by heating diphosphates other than 5K_1.4Zn_1.3P₂O₇ · 16H₂O, showed reorganization to diphosphate above 400 ° C according to the reaction M₂O₃PO[P(O₂M)O] _n PO₃M₂ +nM₃PO₄(n + 1)M₄P₂O₇ where M represents K and/or 1/2Zn.     

Preparation and thermal properties of zirconium tungstate/copper composites

ZrW₂O₈/Cu composites were prepared by the powder metallurgy method. Electroless plating was used to deposit copper on ZrW₂O₈ powder before sintering. The thermal expansion and thermal conductivity of composites were measured in the temperature range from 25 ^oC to 200 ^oC and compared with those predicted from various theoretical models. The results show that the coefficient of thermal expansion of ZrW₂O₈/ Cu composites with a different volume fraction of ZrW₂O₈ is greater than the theoretically calculated value. The thermal conductivities of ZrW₂O₈/ Cu composites increase with a higher copper content and decrease upon elevated temperature. The thermal conductivity of composites with a different volume fraction of ZrW₂O₈ is lower than the theoretically calculated value.     

含锆耐高温陶瓷化先驱体的合成和性能研究

以丁基锂、三氯乙烯、苯乙炔和四氯化锆为原料,合成了一种耐高温的含锆陶瓷化先驱体(简称PZA)。采用FT-IR和GPC对树脂结构进行表征,通过TGA和XRD对聚合物耐热性和陶瓷化转化进行研究。结果表明,PZA树脂具有优良的耐热性能和陶瓷化转化性能,N2气氛下Td10(质量损失10%的温度)达600℃,1 000℃下的质量保留率为61.9%,1 450℃下完全热解为Zr C。     

The thermal behaviour of copper diphosphates made by wet process

Copper diphosphates (Cu₂P₂O₇ · 5H₂O, Cu_1.6K_0.8P₂O₇ · 1.7H₂O, and Cu_1.5K_1.0P₂O₇ · 2.8H₂O) were made by mixing aqueous solutions of tetrapotassium diphosphate and copper dichloride. When the diphosphates were heated, the decomposition of the diphosphates to orthophosphate was observed at a temperature lower than 150° C. The orthophosphate was polymerized by condensation to polyphosphates in the temperature range of about 150 to 450° C. The polyphosphates reorganized to diphosphate at 450 to 550° C according to the following reaction:

Synthesis and catalytic properties of a new window type hybrid porous zirconium phosphonate

An organic–inorganic hybrid zirconium phosphonate (noted as ZrNCP) with window type porous structure was synthesized by using β–alanine–N,N-dimethylidenephosphonic acid and zirconium dichloride oxide octahydrate. The sample possesses regular flake morphology, and these flakes have porous framework structure, which were characterized by SEM, HRTEM, N₂ sorption, XRD, TGA–DSC, elemental analysis, XPS, and FT-IR spectroscopy techniques. The as-prepared ZrNCP can be used as catalyst to oxidation of formaldehyde after Fe³⁺ was intercalated and coordinated with nitrogen and carbonyl groups inside the porous walls of ZrNCP. 90.1% of oxidized efficiency was obtained when the catalyst was added into formaldehyde solution (40% water solution) at 80 °C.     

Synthesis of zirconium oxide by hydrolysis of zirconium alkoxide

Submicrometre particles have been prepared from hydrolysis-polycondensation of zirconium alkoxide [Zr(n-C₃H₇O)₄] in ethanolic solution. The properties of these particles (morphology, specific surface area, S _BET, crystal phase and size distribution) after calcination at 450 °C for 5 h were found to depend on the conditions of synthesis, i.e. alkoxide concentration and mole ratio water/alkoxide.     

Cesium dizirconium phosphate: Synthesis and thermal properties

Crystalline CsZr₂(PO₄)₃ with the NZP [NaZr₂(PO₄)₃] structure was prepared by a sol gel procedure. The purity and composition of the sample were determined by scanning electron microscopy with energy-dispersive X-ray analysis as well as by X-ray phase analysis and IR spectroscopy. CsZr₂(PO₄)₃ is thermally stable in the range 7 K < T < 1553 K. Temperature dependences of the heat capacity C _p ⁰ = f(T) and thermal conductivity λ = f(T) of the phosphate in the range 320–650 K corresponding to thermal conditions of a nuclear waste repository were studied. The standard thermodynamic functions C _p ⁰ (T), H ⁰(T)–H ⁰(0), S ⁰(T), and G ⁰(T)–H ⁰(0) were calculated. The thermodynamic functions of formation of CsZr₂(PO₄)₃ were calculated. The possibility of decreasing the temperature of the synthesis-immobilization to 1000 K was experimentally confirmed.     

POSS/PS复合材料的制备及其热性能

单官能团3-氯丙基笼形倍半硅氧烷(POSS)与官能化的聚苯乙烯(PS)进行缩合反应,得到POSS/PS复合材料,其热性能得到明显改善。单官能团3-氯丙基POSS由顶端封角法制备;PS经过3步处理以引入醇钠基团：Friedel-Crafts酰基化反应将羰基引入到PS的苯基上,羰基被硼氢化钠还原为羟基,金属钠与羟基反应生成醇钠基团;单官能团3-氯丙基 POSS分子上的C—Cl与PS上的醇钠基团缩合从而制备POSS接枝的POSS/PS复合材料。利用1H NMR和FTIR技术表征中间产物和POSS/PS复合材料,结果表明POSS笼上的C—Cl与官能化后PS链上的醇钠官能团之间的缩合反应效率很高。XRD测试表明POSS具有良好的分散性。TGA、DSC分析结果表明,由于POSS的引入,POSS/PS复合材料比纯PS的初始分解温度提高69℃,玻璃化转变温度提高16℃。     

相变材料的复合及其热性能研究

针对相变材料应用领域中对相变温度和相变焓的具体要求,采用复合的方法重点对相变材料的相变温度进行调节,复合出具有特定相变温度和较高相变焓的相变材料.论述了相变材料的复合原理,研究了4种相变材料的复合及其热性能,通过理论计算与实际测试相比较,筛选出复合物的最佳配比.研究表明:通过相变材料的复合可以调节材料的相变温度至所需要的范围,并具有较高的相变焓,可保持良好吸收或释放能量的能力.     

芳基二磷酸酯的合成、表征及对ABS的阻燃研究

为了获得无卤阻燃ABS产品,选用了磷酸酯类阻燃剂和成炭剂复配的方式对ABS进行了阻燃研究.合成了两种阻燃剂:四-(2,6-二甲苯基)间苯二酚二磷酸酯(DMP-RDP)、四-(2,6-二甲苯基)对苯三酚二磷酸酯(DMP-HDP),采用FTIR、1H-NMR、TGA等对产物进行了表征.将两种含磷阻燃剂分别和酚醛树脂复配对ABS进行阻燃处理,并研究其热降解行为.氧指数(LOI)测试显示,两种含磷阻燃剂和酚醛树脂复配比例为4:1时,LOI最大,且DMP-HDP的氧指数稍高.结合TGA分析,阻燃剂复配可以促进成炭,磷残留于炭层中,有利于阻燃,炭残余量越大,炭层越稳定,阻燃效果越好.     

The thermal property of alkaline earth diphosphates made by a wet process

Alkaline earth diphosphates [K₂Mg₃(P₂O₇)₂·6H₂0, 2Mg₂P₂O₇·15H₂O, Sr₂P₂O₇·3H₂O, and Ba₂P₂O₇·2H₂O] were made by mixing solutions of tetrapotassium diphosphate and alkaline earth dichlorides. These diphosphates showed the following thermal reactions when they were heated up to 1000 °C:

1. dehydration M₄P₂O₇·nH₂O → M₄P₂O₇·(n?x)H₂O + xH₂O (0
2. degradation M₄P₂O₇ + H₂O → 2M₂HPO₄
3. disproportionation or metathesis 2M₂HPO₄ → M₃PO₄ + MH₂PO₄
4. polymerization 2M₂HPO₄ + nMH₂PO₄ → M_n+4P_n+2O_3n+7 + (n+1)H₂O
5. reorganization or degradation to diphosphate M_n+2P_nO_3n+1 + (n?2)M₃PO₄ → (n?1)M₄P₂O₇
6. reorganization or degradation to tri- and/or diphosphates (for only Ba₂P₂O₇·2H₂O) M_n+2P_nO_3n+1 + 1/2 (n?3)M₃PO₄ → 1/2 (n?1)M₅P₃O₁₀ (n?3) M_n+2P_nO_3n+1 + (n?3)M₃PO₄ → M₅P₃O₁₀ + (2n?4)M₄P₂O₇ (n?3) where M stands for K and/or 1/2Mg, 1/2Sr, or 1/2Ba.

     

Preparation of ultrafine zirconium dioxide particles by thermal decomposition of zirconium alkoxide vapour

Ultrafine zirconia particles are produced by thermal decomposition of zirconium tetratertiary butoxide (ZrTB) vapour. The introduction of ZrTB vapour into the cylindrical electric furnace, is achieved by three different methods: (evaporator, pressurized nebulizer and ultrasonic nebulizer). The properties of the fine particles obtained by these methods are mainly analysed by X-ray diffraction and transmission electron microscopy. It is found that ultrafine zirconia particles produced at relatively low temperatures from 600 to 700° C are spherical in the diameter range 0.035 to 0.15 μm and of tetragonal phase. Furthermore, two-component fine particles of zirconia-ilver are generated by putting the silver solid inside the furnace containing alkoxide vapour, and are deposited by inertia on to a glass substrate under low pressure to form films having a thickness of 17 to 33 μm. The electrical characteristics of the films are evaluated, and the conductance of the film is found to increase with the content of the silver component.     

Thermal expansion and mechanical properties of pure magnesium containing zirconium tungsten phosphate particles with negative thermal expansion

The magnesium composites containing Zr₂(WO₄)(PO₄)₂ (ZWP) particles with negative thermal expansion (NTE) were synthesized. Dense, unreacted Mg/ZWP composites were fabricated by extruding the two component powders. The coefficient of thermal expansion (CTE) and the mechanical properties of the composites were examined. The CTE of Mg/ZWP composites decreased with an increase in the amount of ZWP in the composites, though the effect was not significant probably because of the low bulk modulus of ZWP. Although there was a tension–compression asymmetry in the room temperature yield strength of Mg without ZWP, the difference reduced in the composites. The decreased asymmetry of yield behavior was suggested to be resulting from the tensile residual stress in the matrix produced during fabrication process because of the NTE of ZWP.     

Synthesis, characterization, and thermal properties of biodegradable polyetheresteramide-based polyurethane

In this paper, a new kind of biodegradable polyetheresteramide-based polyurethane (PEEA-U) copolymers were prepared by melt polymerization from ε-caprolactone, 6-aminocaproic acid, poly(ethylene glycol), and toluene diisocyanate. The obtained polymers were characterized by ¹H NMR, FTIR, DSC, WAXD, and TGA/DTG. The water absorption, hydrolytic degradation, and alkaline degradation behavior of these copolymers were also studied in detail.     

Synthesis and formation process of zirconium dioxide nanorods

Crystalline zirconium dioxide nanorods have been prepared by a simple hydrothermal process using zirconium hydroxide as the zirconium raw material. Zirconium dioxide nanorods are composed of monoclinic zirconium dioxide phase, which has been confirmed by the X-ray diffraction analysis. Electron microscopy observations show that the zirconium dioxide nanorods have a single crystal structure, with the rod diameter of less than 100 nm and length of 1–2 μm. Hydrothermal temperature and reaction time play essential roles in the formation and growth of the zirconium dioxide nanorods. Nucleation and crystal growth process are proposed to explain the formation and growth of the zirconium dioxide nanorods.     

Synthesis, microstructure and dielectric properties of zirconium doped barium strontium titanate obtained by solvothermal method

(Ba_0.8Sr_0.2Zr_yTi_1?yO₃) (y = 0.05, 0.1, 0.15 and 0.2) nanosized powders is synthesized by solvothermal method. The formation of (Ba_0.8Sr_0.2Zr_yTi_1?yO₃) was confirmed by XRD, FT-IR and XPS analysis. The purity of the (Ba_0.8Sr_0.2Zr_yTi_1?yO₃) was examined using FT-IR spectroscopy. The X-ray analysis proves that all as-synthesized Ba_0.8Sr_0.2Zr_yTi_1?yO₃ powders have a cubic perovskite structure. The surface characterization indicates the powder contains Zr and Sr elements. SEM investigation shows that the average particle size is reduced with increasing the Zr content and the average particle size is in the range 37–50 nm, the well dispersed nano powders have narrow particle size distribution. The study of dielectric properties shows that the Curie peaks of dielectric constant become broader and shift towards lower temperature on the basis of Ba_0.8Sr_0.2TiO₃ and the dielectric loss decreases with increasing Zr content.     

The preparation and ion-exchange properties of zirconium sulphophosphonates

A number of layered zirconium phosphite arylphosphonate and zirconium phosphate arylphosphonate mixed derivatives have been prepared. These compounds were readily sulfonated in fuming sulfuric acid and the resultant sulfonates behaved as strong-acid ion exchangers. In the case where the aryl group bridged across layers, a non-swelling exchanger resulted, and these solids showed ion exclusion towards large complexes. They also exhibited the selectivity sequences Li⁺ > Na⁺ < K⁺ and Mg²⁺ > Ca²⁺ < Ba²⁺. In the exchanger in which the layers were not connected, large degrees of swelling, to the point of colloid formation, were observed. As a consequence, the rates of exchange were very high. The non-crosslinked exchanger showed increased selectivity for larger cations. In the case of coordination complexes the increased selectivity was remarkable and may stem from a combination of favorable electrostatic and steric factors.