异氰酸酯/可发性酚醛树脂泡沫体的制备

采用端异氰酸酯聚醚预聚物与可发性酚醛树脂制备了新型泡沫体。通过ESI-MS光谱分析和泡沫物理力学性能测试研究了异氰酸酯基团与可发性酚醛树脂比例、异氰酸酯基团和三聚体相对含量、可发性酚醛树脂分子质量对泡沫体制备及性能的影响。结果表明:异氰酸酯基团与酚醛树脂质量比为40/100、三聚体质量分数17.33%、酚醛树脂聚合时间45min时,泡沫体的体积稳定性好,收缩率低;可发性酚醛树脂分子质量增加时,泡沫体的密度从60.16kg/m3增加到63.96kg/m3,基本保持稳定;其弯曲强度为0.2MPa,弯曲应变达到15%以上,远高于纯酚醛泡沫(6%)。在150℃下烘烤2h,泡沫体的质量损失为6%左右,体积变化为-5%左右。泡沫体的热稳定性优于聚氨酯泡沫,同时又有良好的韧性。     

氨基葡萄糖硫酸盐的制备方法研究进展

本文综述了国内外氨基葡萄糖硫酸盐及其复盐制备方法的研究进展,并对各种制备方法的做了对比和评价。     

生物柴油的制备及发展趋势

生物柴油是一种对环境友好可再生燃料,对解决日益枯竭石油资源和由石化柴油燃烧而带来环境问题有重要意义。本文简要介绍了生物柴油的发展现状、定义、特点及其原料,主要论述了生物柴油的制备方法,并且指出了生物柴油的发展趋势。     

Low-temperature synthesis of superfine barium strontium titanate powder by the citrate method

Ba_0.6Sr_0.4TiO₃ powder was synthesized by a citrate method. The phase development was examined with respect to calcining temperature and heating rate during the calcining process. The results reveal a crucial role of the heating rate to the formation of a pure perovskite phase at low calcining temperatures. It was found that keeping relatively low heating rates ≤0.7 °C/min during the calcining process after 300 °C was favorable to a sufficient decomposition of (Ba,Sr)₂Ti₂O₅·CO₃ intermediate phase at low temperatures and consequently led to the formation of a pure perovskite phase at 550 °C. Ba_0.6Sr_0.4TiO₃ powder calcined at the temperature under the heating rate of 0.7 °C/min showed a superfine and uniform particle morphology and high sintering reactivity. As a result, the ceramic specimens prepared from the powder attained reasonable relative densities (94–95%) at sintering temperatures of 1250–1270 °C.     

Synthesis of calcium copper titanate ceramics via the molten salts method

CaCu₃Ti₄O₁₂ has a giant dielectric constant of up to 10⁴ at room temperature and has great potential for various technological applications. In this work, CaCu₃Ti₄O₁₂ ceramic powder was synthesized by heating a stoichiometric amount of CaCO₃, CuO and TiO₂ in molten NaCl–KCl and Na₂SO₄–K₂SO₄, respectively. The synthesis temperature was decreased from 1000 °C (required by conventional solid-state reactions) to 750 °C for NaCl–KCl or to 850 °C for Na₂SO₄–K₂SO₄. The flux type has a larger influence on the phase compositions and morphology of the resultant powders than the synthesis temperature does. The dielectric constant of the resulting ceramics is more than 10⁴ over the wide frequency range from 100 Hz to 100 kHz. The dielectric loss tangent of the resulting ceramics is lower than 0.2 in the frequency range from 100 Hz to 100 kHz. The dielectric behavior of both samples is similar to the results obtained for CaCu₃Ti₄O₁₂ ceramics that were synthesized by the sol–gel method.     

Synthesis and characterization of multiferroic BiFeO3 powders fabricated by hydrothermal method

The influence of processing parameters on phase formation and particle size of hydrothermally synthesized BiFeO₃ powders was investigated. BiFeO₃ powder was synthesized by dissolving bismuth nitrate and iron nitrate in KOH solution at temperatures ranging from 150 to 225 °C. X-ray diffraction patterns and scanning electron microscopy observation indicated that rod-like α-Bi₂O₃ phase was formed at initial stage of reaction and dissolved into ions to form thermodynamically stable BiFeO₃ phase. Single-phase perovskite BiFeO₃ has been formed using a KOH concentration of 8 M at a temperature of ≥175 °C in a 6 h reaction period. BiFeO₃ particle growth was promoted by lowering the KOH concentration, or increasing the duration time or reaction temperature. The effects of processing conditions on the formation of crystalline BiFeO₃ powders were discussed in terms of a dissolution–precipitation mechanism. The magnetization of the BiFeO₃ powders at room temperature showed a weak a ferromagnetic nature.     

Role of V2O5 on the formation of chemical mullite from aluminosilicate precursor

Aluminosilicate precursor for the processing of mulite ceramics was synthesized chemically from inorganic salts following colloidal route. V₂O₅ was used as a sintering additive in different ratios with the precursor powder. The powder mixes were compacted and sintered at different elevated temperatures. The sintered masses were characterized by measuring the bulk density, porosity, flexural strength and fracture toughness. The extent of mullitization and final microstructure of the sintered masses were investigated by scanning electron microscopy and XRD analysis. It was observed that V₂O₅ exhibited favourable effect on the formation of properly crystallized mullite and in the improvement of different mechanical properties.     

国内含铁无机复合高分子絮凝剂开发的进展

文章简述了国内含铁无机复合高分子絮凝剂开发的进展,综合介绍了两类以聚合硫酸铁(PFS)为基础的无机复合高分子絮凝剂(无机铁系型、其它无机含铁型)的制备方法,简单介绍了上述絮凝剂的絮凝性能及其在工业废水处理中的应用,并对无机复合高分子絮凝剂今后发展的方向进行了展望。     

新型高效吸附剂SA-1的合成

以硫酸铝和硅溶胶为原料采用共沉淀法制备硅酸铝类高性能吸附剂,用于蛋白酶类生物活性物质的提取。在反应温度30～35℃,晶化时间为10h,水洗达到SO42-浓度1.0%,经共沉淀、晶化、水洗、喷雾干燥等工序可以制得Al2O3xSiO2yH2O吸附剂,该吸附剂用于人绒毛膜促性腺激素(HCG)的提取,提取回收率达到95.5%和粗品HCG的比活性可以达到900IU/mg。     

水热法制备粉煤灰钙基脱硫剂

文章研究了利用粉煤灰和Ca(OH)2为原料水热反应制备钙基脱硫剂。影响钙基脱硫剂钙剂利用率最主要的因素是水浴温度(TH),它的最佳值是90℃;温度上下浮动5℃,利用率将降低20%。其次还有水浴温度、粉煤灰与Ca(OH)2质量比(FC)、水固比(LS),这些因素的波动对利用率的影响相对较小。水浴时间(tH)达到8 h以上,FC在5～10的范围内变化,LS在8～18的范围内变化均能制备具有较高利用率的钙基脱硫剂。