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乳剂是热力学不稳定体系,其不稳定性是由在分散相和分散介质之间形成最小界面区域的趋势造成的。最小界面区域主要由絮凝和Ostwald ripening决定的。絮凝通常被认为是导致乳剂破坏的最主要原因,但是絮凝可以通过选择适宜的稳定剂来避免。而另一方面,只要有弯曲界面的存在,就会发生Ostwald ripening。这种分散相的传递既有胶束传递又有分子传递,而分子传递不仅与乳滴曲率的不同有关,还与乳滴的组成有关。乳滴组成的不同主要是油相的不同,可以通过油相极性的知识来预测,通常来讲,随着油相极性的增大,乳剂的稳定性降低。
Emulsions are thermodynamically unstable systems, the instability of which is caused by the tendency of the smallest interfacial region to form between the disperse phase and the dispersion medium. The minimum interfacial area is dominated by flocculation and Ostwald ripening. Flocculation is generally considered the leading cause of emulsion damage, but flocculation can be avoided by selecting suitable stabilizers. On the other hand, Ostwald ripening occurs as long as there is a curved interface. This dispersed phase transfer both micellar and molecular transfer, and molecular transfer is not only related to the different curvature of the droplet, but also with the composition of the emulsion. The composition of the emulsion droplets is mainly different from the oil phase, which can be predicted by the knowledge of the oil phase polarity. Generally speaking, the stability of the emulsion decreases as the polarity of the oil phase increases.