摘要
在动态应变条件下,SiO2/PEG200(聚乙二醇,平均分子量为200)分散体系出现了剪切增稠现象.剪切流变实验表明,在两种情况下都出现了剪切增稠:一种是在不同的恒定频率下应变扫描,在临界应力γc出现的剪切增稠;另一种是恒定的应变(γ0=500%)条件下频率扫描,在临界频率ωc≈10rad·s-1出现的剪切增稠.在不同的恒定频率应变扫描条件下,实验研究了储能模量(G′)和耗能模量(G″)与应变的关系,同时初步探讨了应变与不同恒定频率的函数关系.在线性粘弹性区域内,G′和G″满足G′∝ω0.57和G″∝ω0.7指数关系.在恒定的应变条件下,发现模量和复数粘度与扫描频率具有强烈的依赖关系,这些现象可以定性地通过"粒子簇"理论来解释."粒子簇"理论认为这种剪切增稠的发生是由于形成了亚稳定、流动所导致的"粒子簇",使得粘度上升.
Fumed silica suspensions in polyethylene glycol （PEG200） exhibited shear-thickening behavior under dynamic oscillatory strain amplitude. Two regimes of shear-thickening behavior were obtained： the first occured at critical strain amplitude γ0 and different constant frequencies, and the second occured at critical frequency and constant strain amplitude γ0=500%. For the first, the relationships of both of the moduli （G′ and G″） versus strain amplitude were investigated. The strain amplitude as a function of different constant frequencies was observed. In the linear viscoelastic region, the storage （G′） and the loss （G″） moduli depended strongly on frequency with the power-law： G′∝ω^0.57,G″∝ω^0.7. In the second regime, the moduli （G′ and G″） and complex viscosity η＊ showed strong dependence on frequency. The behaviors could be qualitatively explained using the cluster theory, which attributed the phenomena to the formation of metastable, flow induced clusters.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2008年第3期433-436,共4页
Acta Physico-Chimica Sinica
基金
国家自然科学基金(50604017)资助项目
