Spelling suggestions: "subject:"fluorosurfactant interactions"" "subject:"water:surfactant interactions""
1 |
Dobijanje ekstrakta nevena (Calendula officinalis L.) ugljen dioksidom pod pritiskom i njegovo mikrokapsuliranje u sistemu polimer-površinski aktivna materija / Preparation of marigold (Calendula officinalis L.) extract using carbon dioxide under pressure and its microencapsulation in the polymer–surfactant systemPetrović Lidija 01 July 2010 (has links)
<p>Savremene svetske tendencije upućuju na sve širu primenu<br />ekstrakata lekovitog i aromatičnog bilja, kako u prehrambenim<br />proizvodima– funkcionalna hrana, tako i u proizvodima<br />farmaceutske i kozmetičke industrije. Ekstrakti biljnog<br />materijala, dobijeni primenom ugljendioksida pod pritiskom,<br />sadrže termički nepromenjene aktivne komponente, te se<br />poslednjih godina sve više primenjuju u farmaceutskoj i<br />prehrambenoj industriji.<br />Cilj ove doktorske disertacije je da se ispita mogućnost<br />inkorporiranja ekstrakta nevena (<em>Calendula officinalis</em> L.), kao<br />farmakološki aktivne materije, u mikrokapsule sa ciljem zaštite<br />od spoljašnjih uticaja, produžetka njegovog delovanja i<br />proširenja mogućnosti primene.<br />Za dobijanje ekstrakata nevena primenjeni su postupci<br />ekstrakcije ugljendioksidom u tečnom i superkritičnom stanju.<br />Definisani su uslovi pri kojima je moguće dobiti ekstrakat sa<br />visokim sadržajem etarskog ulja, nosiocem gastro-intestinalnog<br />delovanja (200 bar, 40<sup>o</sup>C). Totalni ekstrakt dobijen pod ovim<br />uslovima ekstrakcije je odabran za dobijanje mikrokapsula.<br />Ispitivana je mogućnosti primene polimer–PAM interakcije<br />nejonskih derivata celuloze- hidroksipropilmetil celuloze<br />(HPMC) i anjonske PAM- natrijum dodecilsulfata (SDS), za<br />formiranje omotača mikrokapsula. Primenom konduktometrijske<br />i viskozimetrijske metode, određene su karakteristične<br />koncentracije pri kojima HPMC–SDS interakcija započinje i<br />završava se. Definisan je uticaj osobina molekula HPMC<br />(molekulska masa, stepen supstitucije, vrsta supstituenta) i<br />temperature na širinu intervala interakcije i objašnjeni<br />mehanizmi njihovog povezivanja, sa osvrtom na strukturu i<br />osobine formiranih HPMC/SDS komleksa. Reološkim<br />ispitivanjima pri različitim uslovima definisane su promene u<br />ponašanju sistema u zavisnosti od HPMC–SDS interakcije.<br />Ispitivan je uticaj interakcije na osobine 20% emulzija<br />suncokretovog ulja u vodi određivanjem njihovih reoloških<br />osobina, veličina i raspodela veličina kapi i praćenjem<br />stabilnosti. Utvrđeno je da se u oblasti najizraženije HPMC–SDS interakcije, odnosno kada se na granici faza ulje-voda<br />nalazi umrežen HPMC/SDS kompleks, dobijaju emulzije<br />najveće stabilnosti, sa njajmanjim srednjim prečnikom kapi.<br />Sušenjem emulzija, primenom spray drying postupka,<br />dobijene su mikrokapsule uljnog sadržaja, stabilizovane<br />kompleksom HPMC/SDS. Najbolje karakteristike mikrokapsula<br />(mehanička otpornost, morfološke karakteristike, sposobnost<br />redispergovanja, veličina i raspodela veličina čestica i količina<br />inkapsuliranog ulja), dobijene u oblasti najizraženije interakcije.<br />Dodatak odabranog CO<sub>2</sub> ekstrakta nevena u uljnu fazu<br />emulzija ne menja značajno njihove osobine, kao ni osobine iz<br />njih dobijenih mikrokapsula.<br />Ispitivanja sprovedena u ovoj doktorskoj disertaciji<br />pokazala su da se osobine kompleksa polimer/PAM mogu<br />iskoristiti za mikrokapsulaciju ulja kao nosača farmakološki<br />aktivnih materija.</p> / <p>Contemporary global trends in food- functional food,<br />pharmaceutical and cosmetic industry as well have been<br />focused on a wider medical plants extracts application during<br />the recent decade. Plant extracts obtained by means of carbon<br />dioxide under high pressure contained all unchanged active<br />compounds from plant, so that they have became more<br />popular for application in food and pharmaceuticals recently.<br />The aim of this thesis was to investigate the possibility to<br />incorporate marigold extract (<em>Calendula officinalis</em> L.), as a<br />pharmacologicaly active compound, into microcapsules in<br />order to protect them from surrounding medium, improve<br />their activity and enlarge application.<br />Marigold extracts were obtained by means of carbon<br />dioxide- CO2 under subcritical and supercritical conditions.<br />Extraction conditions under which obtained extract has high<br />content of essential oil, responsible for gastrointestinal<br />activity, were determined (200bar and 40<sup>o</sup>C). Total extract<br />obtained under such conditions, was chosen for microcapsule<br />preparation. Application possibility of polymer–surfactant<br />interaction between non-ionic cellulose derivativehydroxypropylmethyl<br />cellulose (HPMC) and anionic<br />surfactant- sodium dodecylsulfate (SDS) to microcapsule<br />wall formation was investigated. Characteristic<br />concentrations at which interaction starts and ends were<br />determined by means of conductometric and viscometric<br />measurements. The influence of HPMC molecular<br />characteristics (molecular weight, degree of substitution and<br />substituents kind) and temperature on interaction were<br />determined and, considering the structure and characteristics<br />of HPMC/SDS complexes, binding mechanism was<br />explained. The changes in HPMC-SDS system caused by<br />their interaction were defined by rheological investigations<br />that took place under various conditions.<br />The influence of interaction on the properties of 20%<br />sunflower oil/water emulsion was investigated by rheology<br />measurement, particle size and particle size distribution<br />determination and stability testing. It was provided that<br />emulsions prepared in the region of pronounced HPMC–SDS<br />interaction, where HPMC/SDS complex is adsorbed at the</p><p>o/w interface, have highest stability and smallest particle<br />mean diameter.<br />Microcapsules were obtained by spray drying of<br />emulsions stabilized with HPMC/SDS complex. The best<br />characteristics (mechanical resistance, morphological<br />characteristics, redispersing ability, particle size and particle<br />size distribution and amount of encapsulated oil) have<br />microcapsules obtained in the region of most pronounced<br />interaction.<br />Addition of marigold CO<sub>2</sub> extract in to the oil phase of<br />emulsions has no significant influence neither on their, nor on<br />corresponding microcapsules characteristics<br />Investigations conducted in this thesis showed that<br />characteristics of polymer/surfactant complexes can be used<br />in microencapsulation of oil as carrier of pharmacologically<br />active compounds</p>
|
2 |
Formulation de nouvelles mousses d'extinction d'incendie avec impact réduit sur environnement / Formulation of new fire-fighting foams with reduced impact on the environmentArnault, Joris 11 December 2018 (has links)
Les mousses extinctrices sont utilisées sur les feux de catégorie B (solvants inflammables). L’efficacité des mousses actuelles contenant des agents moussants fluorés est apportée par la formation d’un film aqueux à la surface du carburant enflammé. Les entreprises recherchent et développent de nouveaux agents moussants sans fluor car ce type de tensioactif est nocif pour l’environnement et la santé. Des mousses très stables sont nécessaires pour qu'une couche épaisse de mousse résiste aux températures élevées et au démoussage par le solvant et évite ainsi la ré-inflammation.Dans ce travail, l’amélioration de la stabilité de la mousse a été réalisée en utilisant des épaississants dans une solution moussante avec des tensioactifs non fluorés. Des polysaccharides tels que la gomme xanthane ont été utilisés et ses interactions avec des tensioactifs ont été étudiés. Les complexes formés par ces interactions ont été utilisés dans le but d’améliorer la stabilité de la mousse et sa résistance aux flammes. Ceci engendre des mousses de plus faible moussabilité mais de plus grande stabilité. Des tests à échelle réduite ont été réalisés selon la norme EN1568 et ont montré l’efficacité de l’addition de gomme xanthane. Ces formulations innovantes associant des polysaccharides et des agents moussants sont de bonnes alternatives aux formules contenant des tensioactifs fluorés. Le mécanisme d’action des hydrotropes améliorant la moussabilité a aussi été étudié / Firefighting foams are used on class B fires (flammable solvents). The efficiency of currently used foams containing fluorinated foaming agents is ensured by the formation of an aqueous thin film on top of the burning solvent. The formation of such film requires the use of fluorinated surfactants that specifically adsorb at the water-air interface. Companies currently develop fluorine-free products for firefighting foams because this kind of surfactants is harmful for the environment and health. Very stable foams are necessary to the formation of a thick layer of foam that resists high temperatures and defoaming by the solvent, preventing fire re-ignition.In this work, improved foam stability was achieved by using thickeners in the foaming fluid together with the non-fluorinated surfactants. Polysaccharides such as xanthan gum were used and their interactions with surfactants were investigated. Complex species formed by such interactions were used in order to improve foam stability and resistance against flames. This causes a lower foamability but higher stability of foams. Small scale fires extinguishing experiments performed following the standard EN1568 showed the efficiency of xanthan gum addition. These innovative formulations combining polysaccharides and foaming agents are suitable alternatives to those containing fluorinated surfactants. The action mechanism of hydrotropes improving foamability has also been studied
|
Page generated in 0.1119 seconds