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Reologi på gelberedningar
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
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2016 (Swedish)Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesisAlternative title
Rheology on gel compositions (English)
Abstract [sv]

Konsistensen på en gel bestående av tvärbunden hyaluronsyra beror av tre faktorer: total koncentration hyaluronsyra, gelningsgrad och tvärbindningsdensitet. För att utföra detta projekt erhölls tre olika geler med olika tvärbindningsdensitet. Dessa geler späddes dels med lösning av fri, icke tvärbunden, HA från 100 % gelningsgrad till 90 % och 80 %. De olika gelningsgraderna späddes också med natriumkloridlösning från den totala koncentrationen HA, 35 mg HA/g gel, till 25 mg/g och 15 mg/g. Projekts huvudfråga är att kartlägga gelens reologiska egenkaper då både total koncentration HA och gelningsgrad varieras. För att kunna kartlägga detta har en reometer brukats där följande tre tester körts: tidssvep, frekvenssvep och amplitudsvep. Från erhållen data har sedan två parametrar som representerar gelkompositionernas viskösa egenskaper (G'') och elastiska egenskaper (G') observerats. Även mätning av extruderingskraft har genomförts för att dra vidare paralleller och slutsatser mellan extruderingskraften och de reoligiska egenskaperna. Ur resultaten ses att förlusttangenten tenderar att sjunka när gelningsgraden ökar, d.v.s. gelerna blir då mer viskösa och mindre elastiska. Förlusttangenten sjunker även vid ökande total koncentration HA vilket betyder att G’ ökar mer än G’’ i vardera punkt som gör att förlusttangenten minskar.Det gick även att avläsa att de viskösa egenskaperna i gelen ökar då total koncentration hyaluronsyra minskar samt att de viskösa egenskaperna i gelerna minskar vid en sjunkande gelningsgrad.

Mellan gelningsgrad 90-100 % och total koncentration HA 25-35 mg HA/g har analyserna som gjorts i detta projekt gett följande slutsatser. Konsistensen på gel A och C är mer påverkade av gelningsgraden än total koncentration HA. För gel B kan ingen dominerande parameter utläsas.

Abstract [en]

The softness of a gel made of crosslinked HA (HA = hyaluronic acid) depends onthree factors. One is the amount of free hyaluronic acid in the gel. Another is thedensity of the crosslinked network, which is the molecular entanglements in the gel.The third is the total concentration of HA. In this project a rheometer is used to measure the rheological properties by runningthe following tests: time sweep, frequency sweep and amplitude sweep. From theobtained data, parameters related to viscous properties (G’’) and elastic properties(G’) of the gels were observed. 27 different compositions of gels with three differentconcentrations (35 mg HA/g, 25 mg HA/g, 15 mg HA/g), three different gel contents(100%, 90%, 80%) and three different densities of crosslinked network (A, B, C) wereanalyzed. To draw further conclusions an analysis of extrusion force was performedas well. The results from the frequency sweeps show that the loss tangent for a gel increasedas the total concentration of HA was reduced and that the loss tangent for a gelincreased as the gel content was decreased. This indicates that the gels become moreviscous when either the concentration of HA or the gel content was decreased. Anincrease in concentration of HA results in an increase of G' and an increase of gelcontent also results in an increase of G'. The results from the amplitude sweeps showthat xG' (xG' = storage modulus at the crossover point between G' and G'') increasesas either the concentration of HA or the gel content is increased. For xStrain (xStrain= deformation of the gel at the crossover point) and xStress (xStress = the stressapplied to the gel at the crossover point) no clear trend can be seen regarding the gelcontent. But an increase in concentration of HA results in an increase of both xStrainand xStress. The results from the analysis of extrusion force show that an increase intotal concentration HA increases the force.

Place, publisher, year, edition, pages
2016. , 31 p.
Series
Technical report / Department of Information Technology, Uppsala University, ISSN 1404-3203TVETVE, TVE 16 020 maj
Keyword [en]
amplitude sweep, complex modulus, crosslink, elasticity, extrusion force, frequency sweep, gel content, hyaluronic acid, loss modulus, loss tangent, viscosity, rheology, rheometer, storage modulus
Keyword [sv]
amplitudsvep, elasticitet, extruderingskraft, frekvenssvep, förlustmodul, förlusttangent, gelningsgrad, hyaluronsyra, komplex modul, lagringsmodul, reologi, reometer, tvärbindning, viskositet.
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:uu:diva-297837OAI: oai:DiVA.org:uu-297837DiVA: diva2:943745
External cooperation
Galderma Nordic AB
Educational program
Master Programme in Chemical Engineering
Supervisors
Examiners
Available from: 2016-06-28 Created: 2016-06-28 Last updated: 2016-06-28Bibliographically approved

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