Różańska Sylwia, Różański Jacek, Wagner Patrycja, Warmbier-Wytykowska Ewelina
Division of Chemical Engineering and Equipment, Faculty of Chemical Technology, Poznan University of Technology, ul. Berdychowo 4, 60-965 Poznan, Poland.
Materials (Basel). 2024 Dec 13;17(24):6090. doi: 10.3390/ma17246090.
The paper presents the results of research on the rheological properties and stability of oil-in-water emulsions containing cellulose derivatives: methylcellulose, hydroxyethylcellulose, and hydroxypropylmethylcellulose. The continuous phase of the emulsion was a 70% ethanol (EtOH) solution by volume. The dispersed phase consisted of mineral, linseed, and canola oils (20% by volume). Rheological measurements were performed in both steady and oscillatory flow. Emulsion stability was assessed on visual observation and changes in droplet diameter over a period of 5 months after preparation. Relatively stable emulsions were obtained without the addition of low-molecular-weight surfactants, exhibiting viscoelastic properties. The presence of ethanol in the continuous phase significantly slowed down the processes of emulsion sedimentation or creaming, as well as droplet coalescence. The reasons for the slow phase separation were linked to changes in density and zero-shear viscosity of the continuous phase caused by the addition of EtOH. All emulsions were highly polydisperse, and the addition of methylcellulose and hydroxypropylmethylcellulose further led to the formation of strongly flocculated emulsions. Droplet flocculation resulted in highly viscoelastic fluids. In particular, for emulsions containing hydroxypropylmethylcellulose, the ratio of the storage modulus to the loss modulus approached a value close to 0.1, which is characteristic of gels.
本文介绍了含纤维素衍生物（甲基纤维素、羟乙基纤维素和羟丙基甲基纤维素）的水包油乳液的流变特性和稳定性的研究结果。乳液的连续相是体积分数为70%的乙醇（EtOH）溶液。分散相由矿物油、亚麻籽油和菜籽油组成（体积分数为20%）。流变测量在稳态和振荡流中进行。通过目视观察和制备后5个月内液滴直径的变化来评估乳液稳定性。在不添加低分子量表面活性剂的情况下获得了相对稳定的乳液，其表现出粘弹性。连续相中乙醇的存在显著减缓了乳液沉降或分层以及液滴聚结的过程。相分离缓慢的原因与添加EtOH导致的连续相密度和零剪切粘度的变化有关。所有乳液都是高度多分散的，添加甲基纤维素和羟丙基甲基纤维素进一步导致形成强絮凝乳液。液滴絮凝导致形成高粘弹性流体。特别是，对于含羟丙基甲基纤维素的乳液，储能模量与损耗模量之比接近0.1，这是凝胶的特征值。
