摘要
采用AR2000ex流变仪对沉淀碳酸钙(PCC)在聚乙二醇(PEG200,平均相对分子质量为200)分散体系中进行动态扫描实验,研究不同固定频率条件下该分散体系的应变剪切增稠及耗能行为。应力—应变曲线(LISSAJOUS曲线)及其归一化曲线表明,在固定频率下随着应变增大,LISSAJOUS曲线围成的面积增大,即体系消耗的能量增大,同时分散体系由线性粘弹性体系转变非线性粘弹性体系。分散体系消耗的能量Ed与应变幅度(γmax)满足以下关系:Ed=K(γmax)α,在剪切变稀区内α≈2,在剪切增稠区内α远大于2。另外还研究了频率(ω)对体系消耗能量Ed的影响,并确立了剪切增稠区的耗能指数(α)与频率(ω)的关系为α∝ω0.23±0.01。这种临时的,亚稳定的"粒子簇"导致可逆的剪切增稠,而这种长大的"粒子簇"阻碍体系的流动,从而使之需要额外的能量。
The dynamic strain amplitude scanning was carried out for precipitated calcium carbonate（PCC） dispersing in polyethylene glycol（PEG200） by using AR2000ex rheometer（TA Company）.The shear-thickening and energy dissipation behaviors were investigated at different fixed angular frequencies.It is illustrated from the LISSAJOUS curves and normalized LISSAJOUS curves that the area enclosed by LISSAJOUS curve and the dissipated energy increases with the increasing of strain at fixed angular frequency and the system transites from linearly viscoelastic to nonlinearly viscoelastic system.The relationship between the energy dissipation Ed and strain amplitude γmax is as follows： Ed=K（γmax）α,where α≈2,in the shear thinning region,and in the shear thickening region α get much higher than 2.The relationship between Ed and the fixed angular frequency（ω） was investigated also.And the relationship between the exponent（α） and the fixed angular frequency（ω） is determined as follows： α∝ω0.23±0.01.The temporary,metastable clusters cause the reversible shear-thickening,while the grown-up clusters can block the flow of the system,which results in the needing of additional energy.
出处
《粉末冶金材料科学与工程》
EI
2010年第4期324-330,共7页
Materials Science and Engineering of Powder Metallurgy
基金
国家自然科学基金资助项目(50774096
50604017)
