共查询到20条相似文献,搜索用时 78 毫秒
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在固体氟橡胶混炼胶中引入端羧基液体氟橡胶(CTLF),研究了混炼胶的加工性能、硫化物性、力学性能和耐高低温性能。结果表明,当羧基质量分数为2.21%的CTLF在混炼胶中质量分数达到10%时,混炼胶的性能最佳,其拉伸强度和撕裂强度分别达到15.7 MPa和33.5 kN/m。CTLF的增强效应源于羧基与混炼胶中的吸酸剂氧化镁之间的离子相互作用,离子型交联是混炼胶力学性能提高的根本原因。此外,CTLF的引入提高了硫化胶的高温残炭率,且对体系的玻璃化转变温度无影响。 相似文献
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以高相对分子质量偏氟乙烯(VDF)-六氟丙烯(HFP)-四氟乙烯(TFE)共聚物为原料,采用一步氧化降解法制备了低相对分子质量的端羧基液体氟橡胶,以六亚甲基二异氰酸酯三聚体为交联剂对其进行交联固化,确定了合成条件,通过傅里叶变换红外光谱和核磁共振表征了端羧基液体氟橡胶,并研究了固化产物的物理机械性能和热性能。结果表明,以KOH为碱时,随着KOH用量的增加,液体氟橡胶的相对分子质量降低(数均分子量较低值为2 200),羧基含量增加,产率可达到98%;随着NCO/COOH(摩尔比)的增加,固化产物的拉伸强度先增加后降低,扯断伸长率先降低后增加,当NCO/COOH为1.20时,固化产物的物理机械性能较好,在800℃时其残炭率为35%,较端羧基液体氟橡胶有所提高。 相似文献
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一种新型聚醚离子液体电解质的制备和表征 总被引:1,自引:0,他引:1
以端羟基聚环氧氯丙烷(PECH)、N-甲基咪唑(NMIM)为原料,制备了一种新型的含端羟基的聚醚离子液体(NMIM-g-PECH)。考察了反应温度、反应配比、反应时间、接枝PECH的数均相对分子质量对反应接枝率的影响;用红外光谱和核磁共振氢谱对聚醚离子液体进行了结构表征;对聚醚离子液体的溶解性、电化学稳定性和离子导电性进行了分析。结果表明合成聚醚离子液体的较优工艺条件为:反应时间10h,反应温度40℃,n(PECH中氯甲基):n(NMIM)=1.0:1.8,PECH的数均相对分子质量为1000,此条件下反应接枝率可达82.3%;所得聚醚离子液体具有良好溶解性、电化学稳定性、离子电导性能,质量分数为5%的这种聚醚离子液体甲醇溶液室温电导率可达2.40×10-3S/cm。 相似文献
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以端羟基聚丁二烯液体橡胶(H11PB)为原料,以有机酸酐为羧化剂,采用端基转化法合成端羟羧基聚丁二烯液体橡胶(HCTPB)。结果表明:在反应温度为80℃,反应时间为3h及羧化剂用量为20%时,可得到质量优良,性能稳定的丁羟羧液体橡胶,且转化率在60%以上。采用红外分析,对不同羧基含量的HCTPB微观结构进行测定,顺、反-1,4与1,2结构含量分别与原料HTPB相近,端基转化过程对HTPB主链微观结构没有影响。 相似文献
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ZHANG Zhikuan ZHANG Dianwei XU Enxia HOU Xinmei DONG Yanling 《中国耐火材料》2007,16(2):22-27
The application of bauxite with low Al2O3 content has been studied in this paper and β-SiAlON has been obtained from two kinds of bauxites (Al2O3 content 68.08 mass% and 46.30 mass% respectively) by aluminum reduction and nitridation method. The sequence of reactions has been studied using thermal analysis (TG-DTA), X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) with EDS. Compared with carbon thermal reduction and nitridation of aluminosilicates employed presently, the reaction in the system of bauxite-Al-N2 occurs at lower temperature. β-SiAlON appears as one of the main products from 1573K and exists stably in the range of the present experimental temperature. The microstructure of β-SiAlON obtained at 1773 K is short column with 5-10μm observed by SEM. 相似文献
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Reactions in the system Al-0-C are discussed. Reaction conditions which produce an α-alumina body having a <70%-dense bulk region coated with an impervious, ∼100-μm thick surface layer are described. The development of the unique composite microstructure is attributed to reactions which serve to coarsen internal grains by vapor-phase transport of volatile aluminum suboxides and, thereby, reduce firing shrinkage. Proper control of the furnace atmosphere is necessary to produce the thin, dense surface layer. The effect of varying the carbodalumina molar ratio on linear firing shrinkage, tired density, and weight loss was examined. In addition, the effect of oxygen partial pressure on the oxidation of carbon and the formation of an intermediate reaction product, Al4 O4 C, was examined. 相似文献
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5kA惰性阳极铝电解槽槽膛内形及热平衡 总被引:3,自引:0,他引:3
以有限元软件ANSYS为开发平台,建立了5 kA惰性阳极铝电解槽槽膛内形及热平衡计算模型,计算了过热度和侧部炭块种类对槽膛内形的影响.过热度增大,结壳明显减薄.Si3N4/SiC侧部炭块比普通侧部炭块形成更厚的结壳,但采用普通侧部炭块也能够形成满足要求的结壳厚度,而且普通侧部炭块散热量更少,有利于实现热平衡.热平衡研究表明,采用无烟煤阴极炭块通过强化电流和加强保温可以实现热平衡,但在热平衡时底部等温线分布仍然不合理,石墨化阴极比普通阴极更难实现热平衡,但在热平衡时能够保证底部等温线的合理分布,热平衡时电流强度为6.4kA,极距为90mm,电解槽电压为7546mV. 相似文献
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Reduction in Aluminum Alloy Attack on Aluminosilicate Refractories by Addition of Rare-Earth Oxides 总被引:1,自引:0,他引:1
Several aluminosilicate compositions were tested for molten 7075 aluminum alloy attack with and without the addition of 10% Na2 CO3 . The extent of corrosion was proportional to the silica content of the refractory and especially of the matrix phase. The addition of rare earths up to 15% by weight to the aluminosilicates virtually eiiminated corrosion. Bastnasite, a rare-earth concentrate, was found to be a more effective additive at low concentrations than either CeO2 or La2 O3 alone in rendering the aluminosilicates corrosion resistant. 相似文献
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Thermal Expansion Reduction in Alumina‐Toughened Zirconia by Incorporation of Zirconium Tungstate and Aluminum Tungstate
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Carl P. Romao Bojan A. Marinkovic Ulrike Werner‐Zwanziger Mary Anne White 《Journal of the American Ceramic Society》2015,98(9):2858-2865
A series of composites containing yttria‐stabilized zirconia, Al2O3, and the thermomiotic (negative thermal expansion) materials ZrW2O8 and Al2W3O12 were prepared by an in situ solid‐state reaction during sintering. Microstructural analysis of the composites indicated several sub‐micron sized components. 27Al MAS NMR was used to characterize the aluminum‐containing phase distribution. Measurement of the coefficients of thermal expansion showed that the addition of thermomiotic components reduced the thermal expansivity of the alumina‐toughened zirconia matrix, but the reduction was considerably smaller than what would be predicted by the rule of mixtures. The Turner model was much more accurate in predicting the coefficients of thermal expansion of the composites due to the large differences in stiffness between the components. 相似文献