Physico-chemical properties evaluation of emulsions with nonionic emulsifiers

V kozmetiki pogosto uporabljamo emulzije. Ker so termodinamsko nestabilne, nas zanima, kateri parametri najbolj vplivajo na njihovo kinetično stabilnost. Z uporabo homogenizatorja smo izdelovali dve vzporedni seriji emulzij, prvo z vodo in olivnim oljem, ter drugo z vodo in ricinusovim olje. Uporabili smo štiri različne neionske emulgatorje oz. emulgatorske zmesi, ter proučili njihovo učinkovitost. Spremljali smo njihovo uspešnost pri zniževanju medfazne napetost, zanimal pa nas je tudi vpliv vrednosti HLB emulgatorjev na lastnosti emulzije. Vrednost HLB naj bi vplivala na tip emulzije ki nastane, ter njeno dobro stabilnost, kadar se vrednost emulgatorja ujema z zahtevano vrednostjo oljne faze. Spremljali smo tudi velikost kapljic pri različnih razmerjih oljne in vodne faze ter različnih koncentracijah emulgatorjev in viskoznost izdelanih emulzij. Tekom poskusov smo ugotovili, da vrednost HLB ni imela glavnega vpliva na stabilnost, na velikost kapljic pa je bolj vplival postopek izdelave emulzije. Enakomernost porazdelitve velikosti kapljic prav tako ni bila glavni pogoj za dolgoročno stabilnost. Najizrazitejši vpliv na stabilnost je imela viskoznost pripravljene emulzije. Izkazalo se je, da so bile dolgoročno stabilne le emulzije z visoko viskoznostjo ali pa vsaj srednjo viskoznostjo. Nobena od emulzij z nizko viskoznostjo ni bila stabilna.Emulsions are commonly used in cosmetics. Since emulsions are thermodynamically unstable, we are interested in which parameters are the most influential on their stability. Using a homogenizer, two parallel series of emulsions were produced, first with water and olive oil, and the other with water and castor oil. We used four different non-ionic emulsifiers or emulsifying mixtures, and studied their efficacy. We observed their performance in lowering the interfacial tension and the influence of HLB values of the emulsifiers. The HLB value should affect the type of emulsion produced, and the stability of emulsions if the emulsifier value matches the required oil phase value. We also monitored the size of the droplets in the various fractions of the oil and water phase and the various concentrations of emulsifiers. During the experiments, we observed that the HLB value did not have the main effect on stability, and the droplet size was more influenced by the process of making the emulsion. Homogeneous droplet size was also did not have a major impact on long-term stability. The highest effect on stability had the viscosity of the prepared emulsion. It turned out that in the long term only emulsions with high viscosity or medium viscosity were stable. None of the emulsions with low viscosity was stable