阻燃改性苎麻增强环氧树脂复合材料制备及性能研究

采用紫外光接枝的方法,将甲基丙烯酸缩水甘油酯(GMA)接枝到苎麻织物上,再胺化、磷酸化,对苎麻织物进行阻燃改性,并利用手糊成型的方法制备了阻燃改性苎麻增强环氧树脂(EP)复合材料。用拉伸试验机和氧指数仪等研究了复合材料的力学性能和阻燃性能,用扫描电子显微镜观察了复合材料的拉伸断面形貌和燃烧残炭,并讨论了不同GMA接枝率对复合材料力学性能和阻燃性能的影响。结果表明,阻燃改性的苎麻织物与EP之间的粘结效果明显改善,提高了复合材料的力学性能和阻燃性能,接枝45%GMA的苎麻胺化、磷酸化后与EP复合,可使复合材料的极限氧指数达到25.6%。     

钛酸钾晶须在树脂基摩擦材料中的应用研究进展

介绍了钛酸钾晶须(PTW)的分类和晶体结构,并简要阐述了其表面改性方法,包括偶联剂改性、多元复合处理方法等;详细综述了PTW在不同树脂基摩擦材料中的应用情况,并提出了其今后的发展方向。     

PPO/PA6合金改性技术的研究

为了使聚酰胺6(PA6)、聚苯醚(PPO)的性能互补,采用共混改性的方法制备综合性能优异的PPO/PA6合金,并对PPO/PA6共混改性技术进行研究。结果表明,苯乙烯系产品(SEBS)不仅可以提高PPO/PA6合金体系的相容性,而且同时还能起到增韧作用。     

酸改性活性炭对甲苯、甲醇的吸附性能

分别用1 mol·L^-1硝酸、1 mol·L^-1盐酸、1 mol·L^-1硫酸对商业活性炭进行浸渍改性。采用比表面积及孔径分析仪、Boehm滴定、傅里叶转换红外光谱(FTIR)对活性炭的物化性质进行表征。以甲苯、甲醇为吸附质,在283 K下进行了固定床吸附实验。研究表明:酸改性能去除表面碱性基团,显著增加表面酸性含氧官能团的含量;酸改性活性炭的吸附量与其比表面积、总孔容、微孔孔容、表面总酸性官能团呈现出良好的线性关系;Langmuir方程比Freundlich方程更加适合描述甲苯、甲醇在活性炭上的吸附;甲醇在活性炭上为物理吸附,甲苯在活性炭上以物理吸附为主,与表面官能团之间的化学键作用能增强甲苯吸附量;甲苯、甲醇在活性炭上的微孔有效扩散系数的大小顺序为:AC-N>AC-1>AC-S>AC-C;并且甲醇的微孔有效扩散系数大于甲苯。     

改性桑树枝焦对模拟烟气中汞的吸附性能

采用固定床热解、蒸汽活化和改性剂(H₂O₂、ZnCl₂和NaCl)浸渍等方法制得不同的桑树枝焦。在固定床吸附实验台上,研究了蒸汽活化、改性剂、吸附温度和烟气组分等对改性桑树枝焦汞吸附性能的影响。结果表明:蒸汽活化显著提高了桑树枝热解焦的比表面积,H₂O₂改性可进一步提高桑树枝蒸汽活化焦比表面积并改善其孔隙结构参数,ZnCl₂和NaCl改性则降低了桑树枝蒸汽活化焦的比表面积、D-R微孔容积和总孔容。10%H₂O₂和30%H₂O₂浸渍改性桑树枝焦的单位汞吸附量分别是蒸汽活化焦的2.02倍和1.77倍;相同改性剂浓度下,ZnCl₂改性焦的单位汞吸附量比NaCl改性焦稍好;随着ZnCl₂浓度增大,改性桑树枝焦的汞吸附性能增强,MT600-A-ZnCl₂(5%)桑树枝焦的单位汞吸附量达到29.55 μg·g^-1,是蒸汽活化焦的3.37倍。在吸附温度为60～120℃范围内,H₂O₂改性焦的汞吸附效率及单位汞吸附量随着吸附温度的升高而下降,而ZnCl₂改性焦的单位汞吸附量则随着吸附温度提高呈现先增大后减小的趋势,最佳吸附温度为90℃。烟气中SO₂和NO组分对汞吸附性能有一定的抑制作用,随着SO₂和NO浓度的增加,汞吸附效率和单位汞吸附量均稍有下降。     

矿物表面性质生物调节机理的研究

在生物选矿过程中,生物作用主要是发生在矿物表面,利用生物的调节作用使矿物表面电性、疏水性及润湿性等发生改变,有利于矿物的生物加工与处理。微生物在矿物表面产生的界面作用涉及的是复杂的物理化学过程,笔者对矿物表面与微生物之间的静电引力作用、特性吸附作用、黏附作用和微生物对能源物质需求的作用等进行分析,探讨了微生物对矿物表面的作用特点及矿物表面物理化学特性的变化规律,为深入研究和揭示矿物表面的生物调节改性的机理提供了一定的理论参考。     

电气石粉体表面改性及其应用研究进展

电气石是环状结构硅酸盐矿物,因其具有压电性、远红外性等特性而具有巨大的应用价值。从改性方法、工艺、表面改性剂及其配方等方面综述了电气石粉体表面改性现状,重点介绍了机械力化学改性法和表面有机包裹法及其相应的改性原理与基本工艺流程;概述了改性后的电气石粉体在水处理﹑医疗保健﹑节能环保﹑纺织等方面的应用情况;并对电气石粉体改性的发展趋势及其应用前景做了展望。     

2′-脱氧尿嘧啶5位碱基修饰的核苷衍生物研究进展

核酸在活体细胞中发挥着重要的作用,它们通过存储和转录基因信息直接控制蛋白质的表达,在分子生物学方面有着广泛的应用。人工合成的寡核苷酸以其可以随心所欲地合成所需序列,杂交时间短,价格低廉越来越受到人们的关注。综述了以天然脱氧核糖核酸的组成中脱氧尿嘧啶核苷为基础,对其碱基的5位进行结构修饰的研究进展,展望了其发展趋势及应用前景。     

Adsorption of copper on specifically modified polyamide sorbent

A novel, specific sorbent based on polyamide covalently immobilized with dead yeast cells by glutaraldehyde was prepared and characterized. This sorbent exhibits a high capacity for metal complexation based on multifunctional groups of dead cells, as well as a good stability for reuse based on the crosslinking agent, glutaraldehyde. The Cu²⁺ sorption characteristics of the polyamide modified with immobilized dead cells were studied and compared to those of the polyamide chemically modified without cells. The adsorption capacity of specifically modified polyamide was about 19‐fold higher than the chemically modified polymer. The adsorption isotherms of Langmuir and Freundlich for the new specific sorbent were determined. The effect of pH, temperature and co‐ions (Zn²⁺, Pb²⁺, Co²⁺, Ca²⁺ and Mg²⁺) on the Cu²⁺ sorption capacity were studied. The effectiveness of heavy metal desorption and the coefficient of recovery of sorption ability were determined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 80–85, 2003     

Toughening modification of PS with n‐BA/MMA/styrene core–shell structured copolymer from emulsifier‐free emulsion polymerization

Core–shell structured particles, which comprise the rubbery core and glassy layers, were prepared by emulsifier‐free emulsion polymerization of poly(n‐butyl acrylate/methyl methacrylate)/polystyrene [P(n‐BA/MMA)/PS]. The particle diameter was about 0.22 μm, and the rubbery core was uncrosslinked and lightly crosslinked, respectively. The smaller core–shell structured particle–toughened PS blends were investigated in detail. The dynamic mechanical behavior and observation by scanning electron microscopy of the modified blend system with core–shell structured particles indicated good compatibility between PS and the particles, which is the necessary qualification for an effective toughening modifier. Notched‐impact strength and related mechanical properties were measured for further evaluation of the toughening efficiency. The notched‐impact strength of the toughened PS blends with uncrosslinked particles reached almost sixfold higher than that of the untoughened PS when 15 phr of the core–shell structured particles was added. For the crosslinked particles the toughening effect for PS was not obvious. The toughening mechanism for these smaller particles also is discussed in this article. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1290–1297, 2003