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Polisaharidni aerogeli za izboljšanje biodostopnosti v vodi slabo topnih substanc
Maja Gračnar, 2015, undergraduate thesis

Abstract: Namen diplomskega dela je bil sintetizirati štiri različne aerogele iz guarja, ksantana, alginata in nizkometiliranega pektina. Da smo dobili gel, smo uporabili direktno metodo geliranja v etanolu, v katerem smo raztopili tudi aktivno substanco nifedipin, ki se je tako vezala na pripravljene gele. Gele smo nato superkritično sušili s CO2. Ker v superkritičnem območju obstaja le ena faza in zaradi tega ni površinskih napetosti, ki bi povzročile krčenje por v gelu, se struktura gela ne poruši. Po tem, ko so spet doseženi normalni pogoji, pa je CO2 ponovno v plinastem stanju. Dobljeni aerogeli so zaradi visoke poroznosti in velike specifične površine primerni za nosilce aktivnih substanc in nadaljnje kontrolirano sproščanje. So tudi netoksični, biokompatibilni in biorazgradljivi, zaradi česar so prijazni tako človeku kot tudi okolju. Po superkritičnem sušenju smo z in vitro testi sproščanja preverjali, kako se iz nosilcev sprošča aktivna substanca v različnih simuliranih prebavnih tekočinah. Ugotovili smo, da se je aktivna substanca iz alginatnega in pektinskega aerogela sprostila že po petih urah, med tem ko se je iz guarjevega in ksantanskega aerogela tudi po 24 h sprostila minimalna količina aktivne substance. Po končanem eksperimentalnem delu smo določili še kinetični model sproščanja.
Keywords: aerogel, ksantan, guar, pektin, alginat, nifedipin
Published in DKUM: 30.10.2015; Views: 1428; Downloads: 154
Full text (1,99 MB)

Rheological studies of concentrated guar gum
Marija Oblonšek, Sonja Šostar-Turk, Romano Lapasin, 2003, original scientific article

Abstract: Polymers and surfactants are essential ingredients of the printing paste. Polysaccharides are used commercially to thicken, suspend or stabilise aqueoussystems. Also they are used to produce gels and to act as flocculates, binders, lubricants, to serve as modifiers of film properties, and have a function as adjusters of rheological parameters. Surfactants, on the other hand, perform numerous functions acting as dispersants, wetting agents, emulsifiers and antifoaming agents. The rheological properties of polysaccharide thickeners (guar gums with different substitution levels and different producers) at different concentrations and temperatures and, second,the effects produced by the addition of nonionic surfactants (polyoxyethylene stearyl alcohols with different numbers of EO groups) have been studied under linear and nonlinear shear conditions. Experimental data have been correlated with the different modelsČ flow curves with the Cross, Carreau and Meter-Bird model, and mechanical spectra with the generalized Maxwell model and Friedrich-Braun model. The surface tensions of aqueous systems containing polysaccharide andžor surfactants have been determined overextended concentration ranges in order to detect the CMC conditions and toprovide a better understanding about the polysaccharide-surfactant interactions.
Keywords: textile printing, printing pastes, polysaccharides, thickeners, rheology, viscoelasticity, surfactants, guar gum
Published in DKUM: 01.06.2012; Views: 2589; Downloads: 90
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Good quality printing with reactive dyes using guar gum and biodegradable additives
Reinhold Schneider, Sonja Šostar-Turk, 2003, original scientific article

Abstract: In printing with reactive dyes sodium alginates or synthetic thickeners are typically used as thickening agents to prevent unacceptable fabric handle. A new reactive printing process for reactive dyes on cellulosic textiles has been developed using natural thickening agents and environmental-friendly additives. Printing trials with guar gums have shown that the use of differentadditives can prevent fabric stiffness. These additives have no significant influence on rheology and colour strength but contributed to soft fabric handle even when guar gums were used as thickening agent. The use of additives and guar gum provide good quality prints with reduced wastewater pollution.
Keywords: textile printing, guar gum, additives, fabric handle, printing quality, ecology, environmental protection
Published in DKUM: 01.06.2012; Views: 3270; Downloads: 92
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