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以偶氮二异丁脒盐酸盐(V50)作为引发剂,失水山梨醇硬脂酸酯(Span60)和聚二甲基硅氧烷PEG-7磷酸酯为复合分散剂,蔗糖烯丙基醚和三甲基丙基聚氧乙烯(15)醚三丙烯酸酯为复合交联剂,丙烯酸为单体,正已烷为反应介质,采用反相悬浮聚合方法制备了球状卡波树脂.用光学显微镜和扫描电镜分别对聚合反应的成粒过程和产物的形貌进行了研究.结果表明,聚合体系呈现典型的悬浮聚合相态特征,并获得了堆积密度较高(0.65 g/cm3)的球状卡波树脂.聚合反应动力学研究结果表明,该反相悬浮聚合的聚合速率对单体浓度和引发剂浓度的反应级数分别约为1.36和0.70;聚合反应的表观活化能为78.0 kJ/mol.交联剂对卡波树脂的性能有重要的影响,通过适度交联可提高产物的增稠效率及其抗剪切性能. 相似文献
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用电子探针对广西金牙微细粒金矿金赋存状态的研究 总被引:1,自引:0,他引:1
微细粒金赋存状态的研究,对搞清此类金矿的成因,指导这类金矿的勘探、开采和选冶有着重要意义,本文报道了用电子探针对广西金牙微细粒金矿的矿石进行了观察分析,首次在金牙金矿床含金矿化物表面发现了含铂汞金矿、汞金矿、铂金太航自然金,并确定出它们的尺度。 相似文献
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The Ta/Si multilayers on (100) Si substrate have been studied over the annealing temper-ature range from 500 to 900℃ by X-ray diffraction and cross-section transmission electron microscopy. The periodicity of the multilayers becomes worse with increasing annealing tem-perature and disappears at 750℃. At 600℃, two kinds of modulation wavelength coexist because the size of several TaSi2 grains is larger than the contracted original modulation wavelength. The films are contracted after annealing. The largest contraction, at least 40nm decreasing in thickness, occurs at 600℃. When the annealing temperature is lower than 600℃, h-TaSi2 grains grow randomly and the growth is not affected by the substrate. At temperatures higher than 750℃, h-TaSi2 grows preferentially in [001] direction parallel to [100] axis of Si substrate. The appearance of texture depends on whether the atomic diffusion is short range or long range at the corresponding annealing temperature. 相似文献
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最近邻密度估计的逐点强收敛速度 总被引:2,自引:0,他引:2
Let X_1,…,X_n be i.i.d,samples drawn from an one-dimenslonal,population withdensity f.Definef_n(x)=(na_n(x))~(1-) sum form i=1 to n K((X-X_i)/(a_n(x))).We study the strong convergence rate of f_n(x) to f(x)at a predetermined point x_o.Under some properly chosen conditions,for f(x_o) and g_n(x_o)proposed in [3],we havepointwisebywhere C_n is any sequence tending to ∞,and n approaches ∞.If f(x)is only assumed tobe continuous at x_o.Then f_n(x_o)may converges to f(x_o)arbitrarily slowly. 相似文献
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The cathode deposit produced by carbon are discharge wae studied by scanning electron microscopy, high resolution electroa microscopy, X-ray diffraction and Raman spectroscopy. The results indicate that the stacking of hexagonal carbon layer in the discharged graphite is different from the ABAB stacking sequence in graphite, and that carboy nanotube is a kind of graphite-like micro-crystal with a low-dimensional structure. 相似文献
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- 4 0℃条件下 ,在 CH2 Cl2 溶剂中以α-氯代乙苯为引发剂 ,Ti Cl4 和 Ti( Oi Pr) 4混合物为 Lewis酸活化剂 ,进行β-蒎烯阳离子聚合 .单独使用强的 Lewis酸 Ti Cl4 时 ,聚合反应在瞬间完成 ,聚合产物的分子量分布较宽 .添加本身无催化活性的弱 Lewis酸 Ti( Oi Pr) 4后 ,聚合反应减缓且聚合产物的分子量分布变窄 .当Ti( Oi Pr) 4/Ti Cl4 摩尔比为 1 /3时 ,产物的分子量随单体转化率线性增加 ,且分子量分布较窄 ,显示出活性聚合特性 .这种活性聚合特性由单体添加实验进一步得到证实 相似文献
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α-蒎烯、β-蒎烯、苧烯阳离子聚合的研究 总被引:1,自引:0,他引:1
比较了萜烯单体α 蒎烯、β 蒎烯、烯的阳离子聚合性能,还考察了这三种单体的活性聚合可能性.在Lewis酸AlCl3作用下,聚合速率大小顺序为:β 蒎烯>烯>α 蒎烯.α 蒎烯、烯的聚合产物分子量较低;β 蒎烯的聚合产物分子量较高.AlCl3与SbCl3复合后,α 蒎烯、烯的聚合速率增加,β 蒎烯的聚合速率反而下降.α 蒎烯的聚合速率增加幅度大于烯,使得前者聚合速率高于后者.与使用AlCl3相比,添加SbCl3后产物的分子量变化是:α 蒎烯变大,烯不变,β 蒎烯则变小.添加SbCl3对β 蒎烯、烯的聚合物结构无影响,而α 蒎烯聚合产物的结构则发生显著变化.活性较高的β 蒎烯在适当的引发体系,如苯乙烯 HCl加成物/TiCl3(OiPr)作用下,可以实现活性聚合.α 蒎烯、烯则由于本身单体活性太小,难以实现活性聚合. 相似文献
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