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石膏是一种用途广泛的工业材料和建筑材料,是生产石膏胶凝材料和石膏建筑制品的主要原料,也是硅酸盐水泥的缓凝剂。工业石膏一般含有一定量的杂质,如碳酸钙、碳酸镁、氯化镁、氯化钠等,因此在用石膏进行生产时都需控制其纯度。通常检测石膏的纯度是测定其中的三氧化硫含量。应用较多的方法有硫酸钡重量法[1-2]、容量法[3]和离子交换法[4]等,这些方法各有优缺点,其中国家标准GB/T5484-2000[1]中规定的硫酸钡重量法是一种比较经 相似文献
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介孔材料的小角度X射线衍射实验条件研究 总被引:1,自引:0,他引:1
对有序结构的介孔材料进行小角度X射线衍射测试,结果表明:通过调整X射线衍射仪的光路系统,控制入射X射线和散射光的强度与覆盖范围,在常规实验条件下不能获得小角度衍射数据的样品,也可获得清晰的小角衍射数据.对于岛津XRD7000型衍射仪,合适的狭缝系统为:发散狭缝0.1°,防散射狭缝0.1°,接收狭缝0.15 mm.测量条件为工作电压40 kV、工作电流40 mA,连续扫描方式,步长0.02°,扫描速率0.5°/min.介孔X衍射图谱主要在1°~2°出现衍射峰,一些0.6°~0.9°的峰可能由仪器设置、样品制备不当所致. 相似文献
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在对角蛋白的结构、分类、提取方法进行介绍的基础上,主要从天然高分子材料的角度,对角蛋白的改性、材料制备及其应用研究进展进行了综述。角蛋白材料常用物理共混和接枝聚合方法进行改性,从而制备环境友好的复合材料;角蛋白的降解主要采取微生物法和酶解法。由于角蛋白水解可产生多种氨基酸,并且具有良好的生物相容性和生物降解性,其主要用作医用材料、药物缓释材料、日用材料、食品包装材料、地膜材料,也可作为较好的重金属离子吸附剂和废水脱色剂。总之,对角蛋白材料的开发和应用具有非常广阔的前景。 相似文献
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本文简述了军事隐蔽材料的隐蔽原理及制备。指出了这类材料是化学、物理、材料等科学综合发展的结果,主要取决于主体物质的化学性能,只有良好的主体物质才会赋 类材料优良的伪装、隐形功能、随着化学科学中无机、有机及金属有机高分子合成技术的发展将会对此有极大的促进作用。 相似文献
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有机荧光防伪材料的制备 总被引:7,自引:0,他引:7
1引言随着社会的不断进步,工农业的发展,档次各异、琳琅满目的商品在促进商品经济高速发展的同时,也满足了人们不断提高的物质生活水平的需要。然而,令人讨厌的伪品也龙蛇混杂地进入了流通市场。伪币、伪票、伪商标掩护下的伪品以及伪证书等常使人受骗,蒙受损失。因... 相似文献
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钠离子电池凭借钠资源丰富、价格低廉在大规模储能领域有着重要应用前景. 然而,钠离子相对锂离子较大的半径和质量限制了它在电极材料中的可逆脱嵌,导致其电化学性能不佳. 因此研发稳定、高效储钠的高比能电极材料是钠离子电池实用化的关键. 另外,进一步优化与电极材料相匹配的电解质来实现高安全、长寿命钠离子电池的构建,推动其商业化进程,也是迫切需要解决的问题. 本文主要对室温钠离子电池关键材料(包括正极、负极和电解质材料)的研究进展进行简要综述,并探讨了其面临的困难及可行的解决方案,为钠离子电池的发展提供一定参考依据. 相似文献
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Zhong Wang Wenhuai Tian Xiaohe Liu Rong Yang Xingguo Li 《Journal of solid state chemistry》2007,180(12):3360-3365
The amorphous carbon coating on the Sn–Sb particles was prepared from aqueous glucose solutions using a hydrothermal method. Because the outer layer carbon of composite materials is loose cotton-like and porous-like, it can accommodate the expansion and contraction of active materials to maintain the stability of the structure, and hinder effectively the aggregation of nano-sized alloy particles. The as-prepared composite materials show much improved electrochemical performances as anode materials for lithium-ion batteries compared with Sn–Sb alloy and carbon alone. This amorphous carbon-coated Sn–Sb particle is extremely promising anode materials for lithium secondary batteries and has a high potentiality in the future use. 相似文献
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Programmed Photodegradation of Polymeric/Oligomeric Materials Derived from Renewable Bioresources 下载免费PDF全文
Dr. Saravanakumar Rajendran Ramya Raghunathan Dr. Ivan Hevus Dr. Retheesh Krishnan Dr. Angel Ugrinov Prof. Dr. Mukund P. Sibi Prof. Dr. Dean C. Webster Prof. Dr. Jayaraman Sivaguru 《Angewandte Chemie (International ed. in English)》2015,54(4):1159-1163
Renewable polymeric materials derived from biomass with built‐in phototriggers were synthesized and evaluated for degradation under irradiation of UV light. Complete decomposition of the polymeric materials was observed with recovery of the monomer that was used to resynthesize the polymers. 相似文献
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Johan Alauzun Ahmad Mehdi Rola Mouawia Catherine Reyé Robert J. P. Corriu 《Journal of Sol-Gel Science and Technology》2008,46(3):383-392
We report the preparation of a new class of lamellar hybrid organic–inorganic materials obtained by self-assembly of bridged
organosilica precursors containing long alkylene chains during the sol–gel process. The self-assembly is induced by lipophilic
van der Waals interactions. The introduction of –SS– bonds in the core of the alkylene chains permitted the functionalisation
of lamellar materials, which were subsequently transformed into SH and –SO3H groups. This methodology was extended to the formation of lamellar hybrid materials containing amino groups thanks to CO2 as bridging groups as well as the formation of lamellar hybrid materials containing carboxylic groups. In this last case,
the hydrolysis and polycondensation of cyanoalkyltrialkoxysilanes permitted the one pot synthesis of lamellar hybrid materials
thanks to in situ hydrogen bonds formation between carboxylic acids groups. All these functional lamellar materials exhibit
a very high chelating capability towards transition metal and lanthanide ions. 相似文献
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生物安全问题已经成为全世界面临的重大生存和发展威胁之一。 在当前我国常态化抗击新型冠状病毒肺炎(COVID-19)疫情的背景下,生物安全的战略地位不断提升,它不仅是对国家安全体系组成元素的不断丰富,而且也将增强我国应对突发公共卫生事件的能力,更是保障国家生物安全的必然选择。 然而,骤然爆发的COVID-19疫情,揭示了世界各国生物安全还存在漏洞。 我国疫情初期,抗疫一线防护装备严重缺乏,检测、监控手段薄弱等,其部分原因是我国生物安全相关的材料研发有所欠缺。 利用新材料来防范生物安全威胁和应对生物安全风险因子,发展生物安全材料学,加强生物安全材料学科建设及人才培养,促进生物安全材料学的发展,具有重大意义。 生物安全材料学的发展,必将满足人民健康、国家战略和国防需求,为我国国家安全提供保障。 相似文献
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Shunzhang You Dr. HuiTeng Tan Licheng Wei Dr. Wei Tan Prof. Cheng Chao Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(48):12237-12256
Silicon-based materials that have higher theoretical specific capacity than other conventional anodes, such as carbon materials, Li2TiO3 materials and Sn-based materials, become a hot topic in research of lithium-ion battery (LIB). However, the low conductivity and large volume expansion of silicon-based materials hinders the commercialization of silicon-based materials. Until recent years, these issues are alleviated by the combination of carbon-based materials. In this review, the preparation of Si/C materials by different synthetic methods in the past decade is reviewed along with their respective advantages and disadvantages. In addition, Si/C materials formed by silicon and different carbon-based materials is summarized, where the influences of carbons on the electrochemical performance of silicon are emphasized. Lastly, future research direction in the material design and optimization of Si/C materials is proposed to fill the current gap in the development of efficient Si/C anode for LIBs. 相似文献