Browsing by Author "Rocha Filho, Pedro Alves da"

Now showing 1 - 3 of 3
  • No Thumbnail Available
    Item
    Attainment of O/W emulsions containing liquid crystal from annatto oil (Bixa orellana), coffee oil, and tea tree oil (Melaleuca alternifolia) as oily phase using HLB system and ternary phase diagram.
    (2008) Morais, Gilsane Garcia; Santos, Orlando David Henrique dos; Oliveira, Wanderley Pereira; Rocha Filho, Pedro Alves da
    Emulsions containing liquid crystals present interesting properties and advantages such as the skin moisturize increase, active release modulation, and emulsion stabilization. In this work, emulsions containing annatto, coffee and tea tree oils, and nonionic surfactants were developed. The HLB method was used for selection of surfactants. The required HLB value was established (9.0). Liquid crystals were attained when used the surfactant mixture Ceteareth-5 and Steareth-2 and identified as lamellar. The emulsions showed pseudoplastic behavior and tixotropy. The ternary diagram was useful in the selection of the proportion of surfactant and oily phase considering skin compatibility and liquid crystal presence.
  • No Thumbnail Available
    Item
    Influence of PEG-12 Dimethicone addition on stability and formation of emulsions containing liquid crystal.
    (2007) Andrade, Fernanda Frota de; Santos, Orlando David Henrique dos; Oliveira, Wanderley Pereira; Rocha Filho, Pedro Alves da
    Oil/water emulsions, containing liquid crystals, were developed employing Andiroba oil, PEG-12 Dimethicone and Crodafos CES . It was evaluated the influence of silicone surfactants on the emulsions stability and on the formation of liquid crystalline phases and therefore, physicochemical characteristics, such as rheology and zeta potential, were evaluated. Emulsions were prepared by the emulsions phase inversion method. All the formulations presented lamellar liquid crystalline phases. The PEG-12 Dimethicone addition did not change microscopically the liquid crystalline phases. The emulsions containing silicone demonstrated lower viscosity than those without the additive. This is an important feature, as the silicone did not change the rheological profile; however, the addition of silicone still can be used as a viscosity controller. The formulations had their viscosity increased 15 and 150 days after their preparation. This characteristic shows that the emulsions have their organization increased along the storing time. In the analysis of zeta potential, we could verify that all formulations presented negative values between )39.7 and )70.0 mV. Within this range of values, the emulsion physical stability is high (Fig. 10). It was concluded that the addition of PEG-12 Dimethicone kept the liquid crystalline phase of the emulsion obtained with Crodafos CES , influencing in a positive way in the system stability.
  • No Thumbnail Available
    Item
    A simple analysis of the changes during evaporation of a commercial emulsion of unknown composition.
    (2008) Bergamaschi, Mateus Machado; Santos, Orlando David Henrique dos; Rocha Filho, Pedro Alves da; Friberg, Stig E.
    Opticalm icroscopayn d centrifugationw ereu sedt o observeth e structuracl hangeds uringe vaporatioonf a commercials kin lotion of unknown compositionT. he degreeo f evaporationw as determinedf rom the changedw eight of a microscopsel ide with the emulsiono n a defineda reaa nd thicknesst,h e evaporation lossv ersust ime being measuredb y a balanceu nder an infraredl amp. The resultsr evealedn ot only whichp artso f the emulsionw erem ostp ronet o evaporationw ithout chemical analysisb, ut alsog aves urprisingin formationa s to whichk ind of structuresw ould appeara fter extensive evaporationT.h e importancoe f thesec hangefso r the actiono f a skin lotioni s brieflyd iscussed.