植物(秸杆)纤维助膨化改性技术研究与应用进展

概述了植物(秸杆)纤维助膨化改性的研究状况,以及几种目前最有发展潜力的应用开发技术,简要介绍了植物(秸杆)纤维助膨化技术在相关领域中的最新应用进展。     

有氧再生废轮胎橡胶粉的制备与表征

在管式炉中对废轮胎橡胶粉进行了有氧再生,并考察了气氛、再生温度和再生时间对废轮胎橡胶粉有氧再生过程的影响。结果表明,有氧条件下橡胶粉的质量损失和溶胶质量分数均随温度升高而增大,溶胶中合成胶分子链之间易发生二次重组再交联反应,天然橡胶分子链则主要发生断裂。240 ℃下橡胶粉在有氧条件下再生10 min时,溶胶质量分数达55.9%。橡胶主链和交联键断裂主要发生了氧化反应,生成含羰基和亚砜基的化合物,同时伴有水和二氧化碳等生成,说明橡胶粉中的橡胶分子链有效断链。     

氮化物陶瓷粉体的制备技术及发展趋势

氮化物陶瓷具有优异的耐高温、抗腐蚀、耐磨损性能,是一类应用广泛的结构功能材料。采用烧结方式制备结构与性能满足要求的氮化物陶瓷材料,有必要首先合成符合一定纯度和烧结活性的氮化合物粉体。本文综述了传统产业化氮化物陶瓷粉体的制备技术,以及新型合成技术的研究进展;对现有技术中存在的问题做了归纳总结,并依据国家政策层面的需求和支持提出该领域的发展趋势。     

Preparation and characterization of a new low infrared-emissivity coating based on modified aluminum

A low infrared-emissivity coating was prepared using modified Al powder and polyurethane as metallic pigment and adhesive. Al powder was coated with polyethylene wax by the flux-capping method to reduce the emissivity and gloss of the coating. The surface morphology and chemical composition of pure and modified Al powders were characterized by scanning electron microscopy and X-ray diffraction. The infrared emissivity of the product was measured by an infrared emissometer. The influences of the modified Al powder content, substrate material, coating thickness, and aging time on infrared emissivity were systematically investigated. The results indicate that modified Al powder decreases not only the gloss of the coating, but also its emissivity within the wavelength range of 8–14 μm. The polyethylene wax/Al composites have a homogenous sheet structure at 30 wt.% Al content, and a lower infrared emissivity. The optimum content of modified Al powder is around 18 wt.%. The coating exhibits a lower emissivity value and excellent optical properties. The infrared emissivity of the composite coating significantly increases with increased thickness, and approaches a constant value when the thickness is more than 80 μm. Accelerated aging test results show that with increased aging time, the coating with modified Al powder has a better aging resistance and lower infrared emissivity than that with pure Al powder.     

铁矿石粉循环流化床煤基直接还原的实验研究

在小型循环流化床中对铁矿石粉在氮气气氛下用大同煤粉直接还原进行了实验研究,在800~950℃考察了反应温度对铁矿石粉的还原程度及还原产物微观结构的影响. 结果表明,随反应温度提高,铁矿石粉还原产物的金属化率及还原度均增加,800~850℃时增幅较大,850~900℃时增幅平缓,900~950℃时又出现较大增幅,950℃时达到63%的金属化率和87%的还原度;与还原前的铁矿石粉相比,还原产物的比表面积和总孔体积在800℃时均增加,而在其他温度时均减小,对应的平均孔径变化规律则相反.     

Study on mechanical properties of powder impregnated glass fiber reinforced poly(phenylene sulphide) by injection molding at various temperatures

The prepreg of continuous glass fiber reinforced poly(phenylene sulphide) (PPS) was prepared using the powder impregnation technique and cut into the pellets, in which the length of glass fibers was the same as the pellets. After injection molding, the mechanical properties were tested and the effects of the pellet length, fiber content, and thermal treatment on the mechanical properties at different temperatures were studied. It is found that the tensile strength and flexural strength of 6‐mm pellet sample are slightly higher than that of 3‐ and 12‐mm pellet samples. The tensile strength, flexural strength, and modulus decrease significantly with increasing the temperature. The notched Izod impact strength at 85ºC is higher than both at 25ºC and 205ºC. At 205ºC, the glass fiber reinforced PPS composites can still keep better mechanical properties. When the fiber content ranges from 0 to 50%, the mechanical properties increase with increasing the fiber contents at different temperatures, except the notched Izod impact strength do not further increase at 145 and 205ºC with raising the fiber content from 40 to 50%. Thermal treatment could improve the mechanical properties of the composites at higher serving temperature. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

钠法漂粉精氯化工艺技术探讨

对钠法漂粉精生产过程中的间歇氯化和连续氯化进行了分析对比,结合实验结果探讨了由间歇氯化法得到的产品质量高的原因。     

粉末浸渍长玻璃纤维增强聚丙烯的注塑

采用粉末浸渍的方法制备连续玻璃纤维增强聚丙烯预浸料,经切割获得长纤维增强聚丙烯粒子,探索了材料的注塑工艺,研究了注塑后材料的力学性能及其影响因素。结果表明,粉末浸渍的长纤维增强聚丙烯经注塑后可获得力学性能的制品;随着预浸料切割长度的增长、纤维含量的增加,材料的力学性能提高;在基体聚丙烯中添加接枝极性基团的功能化聚丙烯,可改善体系的界面结合,提高材料的力学性能,但功能化聚丙烯的含量超过一定值后,材料的冲击强度有所下降;控制注塑时的模具温度,可以改变材料的一些力学性能。     

超细莫来石粉末的成型与生坯特性

采用水解－沉淀法制备超细莫来石粉末（Ａｌ２Ｏ３／ＳｉＯ２＝７４／２６，质量比），用各种干、湿法成型工艺制得生坯，测定了生坯密度、微观形貌、气孔分布等结构物理状态。结果表明：湿法成型坯体密度比干法高约６％～７％，且坯体结构均匀，气孔分布窄（大多数小于４００Ａ），由此导致在同样烧成条件下湿法成型坯体烧结密度大大高于干法（达１８％～１９％）。通过对成型技术、坯体质量的分析评价，找出了适合于超细粉末成型的     

粉体技术与水泥工业

本文从现代水泥生产中的某些方法和技术，说明了粉体技术在水泥工业中的应用情况。阐述了粉体、粉体现象和水泥工业的关系，并进行了实例说明，如：ＣＦ可控流生料均化库、冲击式在线流量计、在线粒度测定器、料仓设计和粉体物料的流动性等。文中还指出粉体过程不同于一般的流体过程，故其自动化技术也落后于其他工业，有关水泥工业的粉体技术，国外一些学者提出了展望。