综合多种测试方法,考察了研磨对茂名高岭石粒径、形貌与微结构等理化性质的影响。重点采用^(29)Si、^(27)Al MAS NMR光谱考察了研磨过程中结构脱羟、Si、Al配位环境变化、新活性位点形成等微结构演变等。结果表明:研磨初期,高岭石六方...综合多种测试方法,考察了研磨对茂名高岭石粒径、形貌与微结构等理化性质的影响。重点采用^(29)Si、^(27)Al MAS NMR光谱考察了研磨过程中结构脱羟、Si、Al配位环境变化、新活性位点形成等微结构演变等。结果表明:研磨初期,高岭石六方片层遭到破碎,颗粒粒径逐渐减小,比表面积在研磨1 h达到最大(43.8 m^2/g);此后,颗粒发生团聚,比表面积减小,样品脱羟量和表面吸附水含量均逐渐增加。核磁Si谱和Al谱分别在化学位移-100.5和14.8处出现新的信号,归属于四面体Si与八面体Al相连顶氧质子化作用而产生的Q^3 Si-OH^+-Al结构。研磨导致高岭石脱羟,Al配位状态从AlⅥ经由AlⅤ逐渐向AlⅣ转变。展开更多
Ethylene-octene copolymer (POE) samples exposed to γ-radiation under a series doses were investigated using solid state ~ 13 C-NMR.The chemical shifts of POE were assigned, and the peak evolution as a function of rad...Ethylene-octene copolymer (POE) samples exposed to γ-radiation under a series doses were investigated using solid state ~ 13 C-NMR.The chemical shifts of POE were assigned, and the peak evolution as a function of radiation dose was discussed.An obviously chain scission was found near the branch carbons, and the ~ 13 C-NMR spectra of the corresponding gels confirmed the result.Linewidths of irradiated POE samples of various absorbed doses were observed to which were related to the molecular mobility of the radiation-crosslinked polymer.展开更多
基金a research grant from the Natural Science and Engineering Research Council of Canadaan equipment grant from the Canada Foundation for Innovationfunding from the Canada Research Chair pro-gram
文摘Ethylene-octene copolymer (POE) samples exposed to γ-radiation under a series doses were investigated using solid state ~ 13 C-NMR.The chemical shifts of POE were assigned, and the peak evolution as a function of radiation dose was discussed.An obviously chain scission was found near the branch carbons, and the ~ 13 C-NMR spectra of the corresponding gels confirmed the result.Linewidths of irradiated POE samples of various absorbed doses were observed to which were related to the molecular mobility of the radiation-crosslinked polymer.
