碳分纳米氢氧化铝悬浮液的流变行为与纳米粒子团聚

Rheology of the nano-aluminium trihydroxide suspension obtained from carbonation precipitation and related analysis of nano-particle agglomeration

碳分获得了微观粒度200 nm×20 nm(长度×厚度)的氢氧化铝。研究了碳分悬浮液的流变行为,在低和高剪切速率下分别表现为胀流型非牛顿流体和假塑性非牛顿流体,同时低剪切下为时变性胀流型流体,而高剪切下触变性不明显。研究表明悬浮液内氢氧化铝存在稳定的网络结构,并可以在一定的温度和剪切破坏后保持和恢复,黏度在切应力接近结构破坏强度时发生震荡。通过流变分析,表明网络结构是悬浮液复杂流变行为的成因,也是碳分氢氧化铝粒子生成和稳定存在的根本原因。悬浮液黏度是颗粒数量、粒度分布的函数,是得到碳分反应制备纳米氢氧化铝团聚动力学的重要参数,其中η0/ηmin分析是可能途径之一。

The size of aluminium trihydroxide particles obtained by carbonation precipitation is shown by TEM to be 200 nm × 20 nm（L × T）. The rheology of the suspension is investigated and results show that the suspension acts as a dilatant and a pseudo-plastic Non-Newtonian fluid at low and high shear rate respectively; it is also a time-dependent dilatant Non-Newtonian fluid with low thixotropy at high shear rate. The study indicates that the aluminium trihydroxide particles in suspension form a stable network structure which can be retained or restored after temperature rise or shear destruction; the viscosity of the suspension fluctuates when the shear stress approaches the network structure destruction level. Related analyses show that the network structure is the origin of the complex fluid behavior and also the reason for nano-particle formation during carbonation precipitation and their stability in suspension. Viscosity is a function of the particle size and particle number in the suspen- sion, and there is a very important parameter in establishing the agglomeration dynamics of the nano-alumina trihydroxide in the liquid phase. Analysis of η0/ηmin is one of the possible ways to study this process.