Properties of hydroxypropylmethyl cellulose stabilized emulsion in the presence of sodium dodecylsulfate

Abstract

Many food, pharmaceutical, cosmetic and chemical products exist in the form of emulsions. A common problem with emulsions is their instability. One method of effective protection against coalescence of the particles is to raise the viscosity and lower surface tension by adding a polymer and low-molar-mass surfactant. Interaction between polymer and surfactant could change the adsorption layer around the oil droplets in emulsion which effects emulsion stability. In this paper, the influence of low-molar-mass anionic surfactant, sodium dodecylsulfate (SDS), on the properties of hydroxypropylmethyl cellulose (HPMC) stabilized emulsion, has been investigated. Changes of viscosity and rheological properties of emulsion caused by the HPMC-SDS interaction in continuous phase were measured and stability of emulsions was observed during two months of storage. Significant increase in viscosity and stability of the emulsions was found at SDS concentrations leading to HPMC-SDS interaction in the continuous phase. Stability of emulsions changed with time and was influenced by the HPMC-SDS interaction.Mnogi prehrambeni, farmaceutski i hemijski proizvodi nalaze se u obliku emulzija. Najveci problem emulzionih sistema je njihova nestabilnost. Jedan od nacina za sprecavanje koalescencije kapi u emulzijama je povecanje viskoziteta kontinualne faze i snizavanje povrsinskog napona, sto se postize dodavanjem polimera, tj. hidrokoloida i povrsinski aktivnih materija. Ukoliko postoji interakcija izmedju polimera i povrsinski aktivnih materija moze da dodje do promene u strukturi adsorpcionog sloja oko kapi ulja u emulzijama, sto utice na njihovu stabilnost. U radu je ispitivan uticaj prisustva nisko-molekularne povrsinski aktivne materije, natrijum dodecilsulfata (SDS), na osobine emulzija suncokretovog ulja stbilizovanih polimerom, hidroksipropilmetil celulozom (HPMC). Odredjivane su promene viskoziteta i reoloskih karakteristika emulzija nastalih interakcijom HPMC-SDS u kontinualnoj fazi. Takodje, pracene su i promene stabilnosti emulzija tokom dva meseca stajanja. Pokazalo se da u uslovima interakcije HPMC-SDS, emulzije pokazuju znacajno povecanje viskoziteta, stepena nenjutnovskog ponasanja i stabilnosti. Stabilnost emulzija se menja tokom stajanja, a najvece promene su zapazene u uslovima interakcije HPMC-SDS.