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首页> 外文期刊>European journal of pharmaceutical sciences >The rheological properties of self-emulsifying systems, water and microcrystalline cellulose.
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The rheological properties of self-emulsifying systems, water and microcrystalline cellulose.

机译：自乳化体系，水和微晶纤维素的流变特性。

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The rheological properties of mixtures of equal parts of a range of ratios of a self-emulsifying system (MP) and water (W) added to microcrystalline cellulose (MCC), have been measured by an extrusion capillary rheometer. These measurements allow assessment of both the shear and tension components of flow plus the elastic behaviour of the wet powder masses, although the results for the estimation of shear stress require careful interpretation due to the limitation of the measuring system and the assumptions made in their derivation. The results indicate that there are three regions of behaviour of the systems, which are all significantly different from the mixtures containing only W and MCC. At low MP contents (1.5--23%), the masses increase in their resistance to shear and elongational flow and have lower elasticity. These similarities in behaviour occur in spite of considerable increase in the viscosity of the MPW mixtures and a change to non-Newtonian flow of the fluid. The behaviour of the 46% MP system is intermediate between these systems and the high MP concentrations (69, 80 and 92%). These latter systems show less resistance to shear and elongational flow than the first group of concentrations, but show considerably higher levels of elasticity. As the resistance to shear decreases, so does the impairment of the surface of the extrudate. There is clear evidence of a systematic change in behaviour of the wet powder masses as the values for the angle of entry of the wet mass into the die when plotted against the ratio of the resistance to die entry (upstream pressure loss) to the shear stress within the die, is linear on a log/log scale. Also, the values of compliance of the systems as a function of shear stress fall on a common curve. Changes in the ratio of the MPW to MCC for a system for a single level of MP (46%) resulted in a change in the values of the rheological parameters but not the type of behaviour. As all these wet powder masses had been shown previously to form pellets by the process of extrusion/spheronization, it is clear that systems with a wide range of rheological characteristics can be processed and no single rheological parameter can be used to provide complete characterisation of the processability of such systems.
机译：已经通过挤出毛细管流变仪测量了加入到微晶纤维素（MCC）中的自乳化体系（MP）和水（W）的比例范围的相等部分的混合物的流变性质。这些测量可以评估流量的剪切和拉伸分量以及湿粉团的弹性行为，尽管由于测量系统的局限性和推导的假设，需要对剪切应力的估算结果进行仔细的解释。 。结果表明，系统存在三个行为区域，它们与仅包含W和MCC的混合物都存在显着差异。在低MP含量（1.5--23％）下，质量块对剪切和伸长流动的抵抗力增加，并且具有较低的弹性。尽管MPW混合物的粘度显着增加并且流体变为非牛顿流，但仍存在行为上的相似之处。 46％MP系统的行为介于这些系统和高MP浓度（69％，80％和92％）之间。与第一组浓度相比，这些后面的系统显示出较小的抗剪切和伸长流动性，但显示出相当高的弹性。随着抗剪切力的降低，挤出物表面的损伤也随之降低。有明显的证据表明，当相对于模具进入阻力（上游压力损失）与剪切应力之比作图时，湿粉末团块行为的系统变化为湿团块进入模具的角度值。在模具中，对数/对数刻度是线性的。同样，系统的柔度值作为切应力的函数落在一条共同的曲线上。对于单一水平的MP（46％），系统的MPW与MCC的比率的变化导致流变参数值的变化，而不是行为类型的变化。由于先前已经证明所有这些湿粉体都是通过挤出/滚圆法形成粒料的，因此很明显，可以处理具有广泛流变特性的系统，不能使用单个流变参数来完整表征这种系统的可加工性。

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