In this paper, the rheological properties, microscopic appearance and macroscopic sedimentation behaviour of 147- and 482-nm polystyrene latices in HEC solutions, bearing different adsorbed poly(ethyleneoxide)-poly(propyleneoxide)-poly(ethyleneoxide) (PEO-PPO-PEO) copolymers are presented and compared with previous results with a 67-nm latex (Langmuir 13 (1997) 2922). The ratio of the steric layer thickness to the particle radius varies from 1:5 to 1:40 for the three latex sizes covering a range of particle softness. The 147-nm latex showed gas, liquid and solid phases, including three phase coexistence with increasing concentrations of HEC. The solid phase was a viscoelastic gel that sedimented slowly and showed initially slow, then faster sedimentation rates for HEC concentrations close to the fluid-gel phase boundary. These properties depended on the adsorbed PEO-PPO-PEO copolymers; the fluid-gel phase boundary moved to lower HEC concentrations with increasing PEO chain length. Oscillatory shear measurements were sensitive to the floc network structure and showed the transition from the fluid to gel phases. The values for the elastic modulus in the gel region were independent of the PEO chain length in the stabilizer implying the presence of similar floc structures with each of the different PEO-PPO-PEO copolymers. Stress relaxation measurements gave long relaxation times (> 10(3) s) and showed that the suspensions were viscoelastic fluids with high zero shear viscosities. Higher values were obtained with longer PEO chain lengths. Extrapolated yield stress values showed stronger flocculation with increasing PEO chain length in the adsorbed stabilising layer. There was good correlation between the extrapolated yield stress and the sedimentation velocity, indicating that the collapse of the floc network is governed by the strength of the inter-particle bonds (for the same floc structure) and also with the long-time behaviour from the stress relaxation measurements. With the 482-nm latex there was less effect of the adsorbed copolymer both for the rheology and sedimentation behaviour, with the particles behaving more like hard spheres. The transition between hard and soft sphere behaviour, interpreted here as the ratio of the steric layer thickness to the particle radius at which the adsorbed stabilising layer starts to have an effect on the rheology and phase behaviour is estimated to be approximately 1:20.

中文翻译：

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界面稳定层对分散在非吸附性聚合物溶液中的悬浮液宏观流动性能的重要性。

本文研究了147和482 nm聚苯乙烯胶乳在HEC溶液中的流变特性，微观外观和宏观沉降行为，这些聚醚胶乳具有不同的吸附聚（环氧乙烷）-聚（环氧丙烷）-聚（环氧乙烷）（PEO-PPO-PEO提出了共聚物，并将其与先前的结果用67nm乳胶进行比较（Langmuir 13（1997）2922）。对于覆盖一定范围的颗粒柔软度的三种胶乳，空间层厚度与颗粒半径的比率在1：5至1:40之间变化。147 nm胶乳显示出气相，液相和固相，包括随着HEC浓度增加而三相共存。固相是粘弹性凝胶，其沉降缓慢，最初显示缓慢，然后对于HEC浓度接近液凝胶相边界的沉降速率更快。这些性能取决于所吸附的PEO-PPO-PEO共聚物。随着PEO链长度的增加，液-凝胶相边界移至较低的HEC浓度。振荡剪切测量对絮状网络结构敏感，并显示了从流体到凝胶相的转变。凝胶区域中的弹性模量值与稳定剂中的PEO链长无关，这意味着每种不同的PEO-PPO-PEO共聚物都存在相似的絮凝结构。应力松弛测量值给出了较长的松弛时间（> 10（3）s），表明悬浮液是具有高零剪切粘度的粘弹性流体。较长的PEO链长可获得更高的值。外推屈服应力值表明，随着稳定层中PEO链长度的增加，絮凝作用增强。外推屈服应力与沉降速度之间具有良好的相关性，这表明絮凝网络的塌陷是由颗粒间键的强度（对于相同的絮凝结构）决定的，并且还受絮凝作用的长期影响。应力松弛测量。使用482 nm乳胶，吸附的共聚物对流变和沉降行为的影响较小，而颗粒的行为更像是硬球。硬球和软球行为之间的过渡在这里被解释为空间层厚度与所吸收的稳定层开始对流变学产生影响的颗粒半径之比，估计相态约为1:20。这表明絮凝物网络的崩溃是由颗粒间键的强度（对于相同的絮凝物结构）和应力松弛测量的长期行为决定的。使用482 nm乳胶，吸附的共聚物对流变和沉降行为的影响较小，而颗粒的行为更像是硬球。硬球和软球行为之间的过渡在这里被解释为空间层厚度与所吸收的稳定层开始对流变学产生影响的颗粒半径之比，估计相态约为1:20。这表明絮凝物网络的坍塌是由颗粒间键的强度（对于相同的絮凝物结构）和应力松弛测量的长期行为决定的。使用482 nm乳胶，吸附的共聚物对流变和沉降行为的影响较小，而颗粒的行为更像是硬球。硬球和软球行为之间的过渡在这里被解释为空间层厚度与所吸收的稳定层开始对流变学产生影响的颗粒半径之比，估计相态约为1:20。