共查询到20条相似文献,搜索用时 93 毫秒
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通过对SOCl2/TiCl4引发体系的α-蒎烯(M1)/苯乙烯(M2)共聚产物进行GPC、1HNMR以及微臭氧化-薄层层析法等分析表征,证明该引发体系能在宽广的单体投料比范围内实现有效共聚。在确认仅生成共聚物的反应条件下,采用Mayo-Lewis式积分法测得该体系在-30℃、[SOCl2]=20mmol/L、[TiCl4]=60mmol/L、CH2Cl2溶剂中的竞聚率分别为苯乙烯r2=2.31±0.15;α-蒎烯r1=0.52±0.06。 相似文献
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对共聚物电解质MA-Na2(顺丁烯二酸钠)/AA-Na(丙烯酸钠)水溶液ηsp/C(比浓粘度)与浓度的关系、中性盐及溶液pH对ηsp/C的影响进行了研究。结果表明,稀释MA-Na2/AA-Na溶液时,ηsp/C急剧上升,而稀释含中性盐(KCl或CaCl2)的MA-Na2/AA-Na溶液体系时(中性盐含量保持0.01mol/L),ηsp/C的变化却不大。添加极少量(〈0.05%)中性盐,可使MA-N 相似文献
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AlOOH对Al2O3直接凝固注模成型坯体强度等性能影响 总被引:6,自引:0,他引:6
为了改善直接注模成型(DCC)氧化铝的坯体性能,在Al2O3-DCC过程中加入AlOOH本文详细研究了Al2O3+AlOOH体系的湿坯性能,干燥行为及烧结致密化过程,结果表明,少量AlOOH加入可显著提高Al2O3的湿坯抗压强度和弹性模量,当AlOOH体积含量〈3.0%时对干燥过程没有影响,干燥坯体经无压烧结后可获得烧结密度达3.97g/cm^3(99.7%TD)。显微结构均匀的α-Al2O3相。 相似文献
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添加剂对新型抗水镁水泥显微结构和性能的影响 总被引:5,自引:0,他引:5
在MgO-MgCl2-H2O-粉煤灰体系中掺入了含磷酸的复合添加剂的氯氧镁水泥硬化体中,生成了结构稳定的5.1.8相(Mg(OH)2:MgCl2:H2O=5:1:8以下简称5相)和难溶于水的磷酸镁相,根据化学反应的热力学计算,X射线衍射谱,扫描电镜的观察和硬化体强度的测定,对复合添加剂增强氯氧镁水泥的作用进行探讨,对于其他添加剂的作用作了简要的阐述。 相似文献
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在硫酸介质中,对铝箔表面进行阳极氧化。最佳条件为:H2SO4(15%),H2C2O4(15g/l),NiSO4(8g/l),NP-10(0.1g/l),电流密度(2A/dm^2),氧化时间(10min),温度(25±1℃)。获得了耐蚀、韧性好和击穿电压高的电绝缘氧化铝膜,这种铝箔用于电磁线圈的绕制,得到了满意的结果。 相似文献
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Quanmin YANG Yongquan LEI+ Changpin CHEN Jing WU Qidong WANG Dept. of Mater. Sci. Eng. Zhejiang Univresity Hangzhou China 《材料科学技术学报》1993,9(2):125-128
The thermal stability of amorphous ternary hydrides Mg_(50)Ni_(50)H_(54) and Mg_(30)Ni_(70)H_(45) and their corre-sponding amorphous binary alloys Mg_(50)Ni_(50) and Mg_(30)Ni_(70) were studied with X-ray diffraction(XRD) and differential scanning calorimetry(DSC). Samples of the amorphous alloys were preparedby mechanical alloying and the amorphous hydrides were obtained by charging the alloys with gas-eous hydrogen at 3.0 MPa and 423 K. It was found that the amorphous hydrides released most oftheir hydrogen before the crystallization of the essentially hydrogen depleted amorphous alloy. Thecrystallization temperature of amorphous Mg_(50)Ni_(50)H_(54) elevated and that of amorphousMg_(30)Ni_(70)H_(45) did not change in relation to the original binary amorphous alloy. This is very excep-tional for amorphous hydrides. The reason for the effects of hydrogen absorption/desorption on thecrystallization of amorphous alloys was discussed. 相似文献
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In Ni_(68)P_(18)Cr_(14) amorphous alloy, the dominant component elements Ni and P were in lower contentin the surface layer, while Cr was enriched. There was a P enrichment region just below the surfaceoxide layer, which was supposed to enhance the surface segregation of Cr. Nickel was less oxidizedthan Cr. 相似文献
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利用~1H—~1H COSY,HMQC等2D NMR技术对一种新的配体N—(对硝基苯基)—N’—(甲氧基羰基)硫脲(H_2pmt(Ⅰ)进行~1H、~(13)C NMR谱数据分析与归属;对于它与Cu~+离子配位的化合物Cu(H_2pmt)_2Cl(2)也作了~1H、~(13)C NMR的测定,归属了它们的所有谱线,对于它们的化学位移与配位行为作了简单讨论。 相似文献
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Melt blends of poly (butylene terephthalate) (PBT) and poly (ethylene naphthalate) (PEN) with 30, 40, 50, 60 and 70 wt% PEN
were prepared using a single screw extruder and injection moulding machine. 13C and 1H nuclear magnetic resonance (NMR) spectra were obtained with a Bruker DRX-400 instrument, on solutions prepared by dissolving
samples of the homopolymers and each blend in deuterated trifluoroacetic acid + chloroform mixtures (1:1 by volume). The absence
of new signals in 1H and 13C spectra, that would be expected to result from transesterification reactions in the PBT + PEN blend system, provides convincing
evidence that such reactions do not occur in these blends under the melt processing conditions that were used. In the light
of published work on solid-state NMR studies of these and related blend systems, and our observations of partial miscibility
with a very small domain size, together with substantial enhancement of the mechanical properties of PBT by blending with
PEN, we conclude that the improvement in mechanical properties arises from molecular scale mixing of the homopolymers and
strong but non-covalent bonding interactions over the very large interfacial area between the PBT-rich and PEN-rich phases. 相似文献
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利用金相,X-射线,DSC,透射电子显微镜研究了氢对Ni25Ti50Cu25合金马氏体相变的影响,结果表明,当氢含量高时,氢与全金元素形成氢化物,与氧化物共存的李晶亚结构马氏体失去热弹性,当氢含量低329ppm时,氢固溶于合金中,随氢含量增加,马氏体相变温度降低,氢使马氏体在热循环过程中发生稳定。 相似文献
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制备了4.6V高截至电压下具有良好循环表现的AlF_3包覆改性LiNi_(0.4)Co_(0.2)Mn_(0.4)O_2正极材料,通过XRD、SEM、交流阻抗(IMP)分析、充放电测试研究了不同用量AlF_3包覆LiNi_(0.4)Co_(0.2)Mn_(0.4)O_2正极材料的结构与电化学性能.结果表明,AlF_3以非晶态形式包覆于LiNi_(0.4)Co_(0.2)Mn_(0.4)O_2材料颗粒的表面.当包覆量<1.0%(摩尔分数,下同)时,AlF_3包覆导致轻微的初始容量损失,但显著抑制了高充电电压下膜阻抗和电荷传递阻抗的增加,较好改善了LiNi_(0.4)Co_(0.2)Mn_(0.4)O_2材料的循环稳定性;当包覆量达到2.0%以上时,因AlF_3无电化学活性,使得初始容量损失过大.综合各方面表现,0.5%AlF_3包覆样品的电化学性能较佳,2.5~4.6V范围0.5C放电容量为182.2mAh·g~(-1),循环30次后容量保持率达88.1%. 相似文献
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两性聚电解质CMCTS-g-(PDMMC-co-PDDAMC)的制备及性能初探 总被引:1,自引:0,他引:1
在K2S2O8/Na2SO3氧化-还原引发体系的引发下,通过甲基丙烯酰氧乙基三甲基氯化铵(DMMC)和烯丙基十烷基二甲基氯化铵(DDAMC)在羧甲基壳聚糖(CMCTS)分子链上的接枝共聚反应,制备了新型两性聚电解质壳聚糖衍生物CMCTS-g-(PDMMC-co-PDDAMC)。对产物的两性聚电解质性能进行了初步的探索性研究,发现CMCTS-g-(PDMMC-co-PDDAMC)在pH=1和pH=11处各出现一个黏度较大值,在pH=5附近达到等电点,黏度最小。在等电点处溶液黏度η和特性粘数[η]随离子强度的增大而增大,在pH=1和pH=11处溶液黏度随离子强度的增大而减小。研究了阳离子种类对CMCTS-g-(PDMMC-co-PDDAMC)溶液黏度的影响。 相似文献