摘要
在AR2000ex型流变仪上对沉淀碳酸钙(Precipitated calcium carbonate,PCC)在PEG(聚乙二醇)悬浮体系进行稳态剪切流变实验。通过2种方法来改变分散体系黏度:1)以PEG200(相对分子质量为200)为连续相,分散体系以10℃为间隔从10℃上升至50℃;2)在30℃用相同的聚合物3种不同相对分子质量的PEG(PEG200、PEG400和PEG600)。结果表明随着温度升高,PCC/PEG200分散体系的临界剪切速率越来越大。在剪切增稠区内流动指数N随温度升高而降低,稠度系数K随着温度升高而升高。临界剪切速率以及临界剪切黏度与温度严格满足Arrhenius关系:η=A exp[Ea/(RT)]。研究发现随温度的变化临界剪切应力不变。随着PEG的相对分子质量增加,分散体系的黏度增加,临界剪切增稠速率减小。PCC粉末的分形结构以及聚集体的形貌使得体系的相对黏度远大于硬球体系的相对黏度。
The steady shear rheological experiments were carried out for concentrated PCC（precipitated calcium carbonate）suspensions in polyethylene glycol（PEG） on AR2000ex rheometer.The viscosity of the suspension was changed by two methods as follows： 1） Temperature of the system increasing from 10 ℃ to 50 ℃ in 10 ℃ inteval for PCC/PEG200 suspensions;2） Using the same oligomer of three different molecular mass,PEG200,PEG 400 and PEG600 at the temperature of 30 ℃,respectively.The results showed that for the PCC/PEG200 suspensions,with the increase of temperature the onset of shear-thickening shifted to higher shear rate.Furthermore,the shear flow exponent N is observed to decrease and the consistency index K increases in shear thickening region.Meanwhile,it is found that the correlations of critical shear rate（γc） and critical viscosity（ηc） vs temperature can be strongly fitted Arrhenius rule：.On the other hand,as the PEG molecular mass increases,the onset of shear-thickening shiftes toward lower shear rates.The fractal structure of PCC particles and the shape of aggregation resulted in the relative viscosity higher than that of dilute rigid particles suspension.
出处
《粉末冶金材料科学与工程》
EI
2011年第3期329-334,共6页
Materials Science and Engineering of Powder Metallurgy
基金
国家自然科学基金资助项目(50774096
50604017)
