Solution phase synthesis of t-ZrO2 nanoparticles in ZrO2–SiO2 mixed oxide

A solution phase synthesis is used to prepare tetragonal zirconia nanoparticles. Ammonia solution and zirconia precursor solution were prepared separately and then mixed together to get colloidal hydroxide precipitate. The colloidal hydroxide was treated with silica sol and then the precipitate was separated and dried. The dried powder was then calcined at different temperatures for 2 and 6?h. The mean particle size of the powder calcined at 1000°C was found to be around 8–10?nm. The thermal analysis of dried powder indicates the formation of bulk tetragonal zirconia phase at 780°C. X-ray diffraction (XRD) and infrared spectroscopic analyses confirm the presence of 100% tetragonal zirconia phase in the powder calcined at 1000°C. The addition of silica stabilised the tetragonal zirconia phase. It is advantageous to use this powder as catalyst or catalyst support that operates at high temperatures.     

超细铜粉的化学镀锡及其抗氧化性能研究

以水合肼还原法制备出平均粒径约1μm的超细铜粉,并对其进行化学镀锡。研究了镀锡层对复合粉末微观形貌及抗氧化性能的影响。结果表明:镀覆质量分数50%的锡后,复合粉末平均粒径有所减小,但在空气中的氧化起始温度从120℃提高到220℃,与镀银层相比,镀锡层在较低温度区间对铜粉抗氧化具有优势。     

废弃离子交换树脂燃烧机理研究

采用热重分析及化学反应动力学研究了3种废弃离子交换树脂(WIER)的燃烧机理。结果表明:3种WIER具有相似的燃烧特性,并且均含有较多结合水和挥发分,结合水析出活化能在12.31～41.12 kJ/mol,与挥发分析出活化能相近;随着温升速率的增加,3种WIER燃烧过程中结合水析出阶段和挥发分析出阶段重合越多;对比3种WIER的12种反应机理,结合水析出阶段最概然机理函数均为G-B方程,而挥发分析出阶段最概然机理函数对应的方程有所不同。     

烟气脱硫石膏综合利用可靠性研究

分别利用X衍射仪和热分析仪对FGD石膏进行分析,FGD石膏的主要成分是CaSO4·2H2O,含有少量碳酸盐、磷酸盐以及未被完全氧化CaSO3等杂质.在高温使用过程中,微量CaSO3在氮气气氛下900℃左右分解释放SO2,但在有氧气氛下不会出现此现象.FGD石膏中重金属Hg的排放存在隐患,Hg排放的主要阶段集中在121℃～166℃温度段,应改进煅烧方法和工艺.而放射性污染则不必考虑,今后应大力推广应用FGD石膏.     

玉米秆与玉米芯热重分析

用热重分析仪对玉米秆和玉米芯的热解和燃烧动力学特性进行了研究,通过热解试验发现玉米秆和玉米芯挥发分的析出基本在一个阶段内完成,而燃烧试验研究表明燃烧过程主要由挥发分的燃烧和焦碳及残余挥发分的燃烧这两个阶段组成。上述结果为进一步有效利用玉米秸秆提供了一定的理论基础。     

微藻热解特性及其动力学分析

通过热重分析手段研究了杜氏盐藻在室温至900℃下的热解行为和特性,采用高纯氮气作保护气,升温速率分别为5℃/min、10℃/min、20℃/min和40℃/min.TG、DTG曲线的分析表明,热解过程随温度升高经历3个不同阶段.此外,随着升温速率增大,热解的初始温度和峰值温度均增大,且总失重增加.采用等转化速率法和主曲线法对盐藻热解过程进行动力学分析.结果表明,表观热解反应遵循单一动力学机理模型,反应动力学过程为简单级数反应机理模型Fn.求得热解反应表观平均活化能Ea为146.3 kJ/mol,指前因子A为4.28×1013s-1,指数n为2.4.     

含碱工业废弃物煅烧特性热重实验研究

采用热分析方法研究了白泥、电石渣、碱渣、盐泥四种工业废弃物及淄博石灰石的煅烧特性,从升温速率、终温以及粒径三个方面分析了样品的煅烧性能。结果表明：各种物质具有不同的初始分解温度,白泥在整个煅烧过程中呈现出两段分解趋势,电石渣、碱渣和盐泥存在三段分解。升温速率越小,分解速率越大,煅烧越充分;终温越高,样品的失重率越大,分解越完全;粒径越小,分解越快。     

Sorption and thermal properties of strongly basic cross‐linked ionic polymer modified with Cr(III) compounds

AV‐17(Cr) material was prepared by modifying a commercial polymer AV‐17 (initially bearing R4N⁺ functional groups) with Cr(III) compounds was investigated. Comparative isotherms characterizing the and ion sorption from solution with pH values of 3 and 8, respectively, at 19°C and 60°C, were obtained using the raw AV‐17(Cl) and the modified AV‐17(Cr) material. The sorption process on AV‐17(Cr) takes place through the coordination of Cr(VI) ions with Cr(III) ions, while on AV‐17(Cl) it is due to an ion exchange mechanism. The sorption isotherms obtained in pH 8 solutions fit perfectly the Langmuir model. The thermodynamic functions ΔG, ΔH, and ΔS characteristic to the adsorption of ions from K₂CrO₄ solutions with pH = 8 were calculated. The active sites belonging to the AV‐17(Cr) material were identified as jarosite type compounds of Cr(III). SEM images show that the Cr(III) compounds are present in the form of ultrafine particles located on the surface and within the bulk phase of the polymer granules. Comparative thermal degradation process of both the AV‐17(Cr) and the AV‐17(Cl) material was conducted in air and in an inert atmosphere (He). The thermal degradation mechanism of sorbent AV‐17(Cr) and exchanger AV‐17(Cl) is proposed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41306.     

Flame‐retardancy properties of tris(2‐hydroxyethyl) isocyanurate based charring agents on polypropylene

Tris(2‐hydroxyethyl) isocyanurate based charring agent (TBCA) was synthesized by melt polycondensation with tris(2‐hydroxyethyl) isocyanurate (THEIC) and terephthalic acid as raw materials. It was characterized by Fourier transform infrared spectroscopy, elemental analysis, ¹H‐NMR, and thermogravimetric analysis (TGA). TBCA was blended with ammonium polyphosphate (APP) to form an intumescent flame retardant (IFR) for polypropylene (PP). The charring properties of TBCA was tested by flame retardancy in the PP/APP/TBCA (PP/IFR₂) composite and compared with that of the PP/APP/THEIC (PP/IFR₁) composite. The results show that PP/IFR₂ had lower flame‐retardant properties but better water resistance than that of the PP/IFR₁ composite because PP/IFR₂ could still obtain a V‐0 rating after it had been soaked in water at 70°C for 96 h, whereas PP/IFR₁ could not achieve any rating after 36 h. Their combustion performance was further evaluated by a cone calorimeter test, their thermal degradation processes were studied by TGA, and the morphology of the char residue was observed by scanning electron microscopy. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41810.     

Effects of different ionizable groups on the thermal properties of waterborne polyurethanes used in bulletproof composites

The thermal stability of the resin matrix is an important factor affecting the safety performance of fiber‐reinforced bulletproof composites (FRBCs) during their service period. In this study, two kinds of waterborne polyurethanes based on polyester diol (PEDL218) and isophorone diisocyanate were synthesized; these were used as the matrix of para‐aramid FRBCs. Their thermal stability and thermal decomposition behaviors in a nitrogen atmosphere were studied by dynamic thermogravimetric analysis techniques. The kinetic parameters, including the activation energy (E) and pre‐exponential factor (A), were calculated by the Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, Kissinger, and ?atava–?esták methods. The results show that the cationic waterborne polyurethane with quaternary ammonium groups has better thermal stability than the anionic waterborne polyurethane with carboxylate groups. Their nonisothermal decomposition mechanisms were studied, and the kinetic parameters were also calculated; this will offer theoretical reference for the manufacturing and application of FRBCs based on waterborne polyurethane. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42374.