diplomsko delo
Urška Sevšek (Author), Peter Krajnc (Mentor), Matjaž Kristl (Co-mentor)

Abstract

Z uporabo emulzijske polimerizacije smo sintetizirali porozne polihipe membrane s 5 % zamreženjem. Uporabili smo monomere stiren, divinilbenzen in 2-etilheksil akrilat. Divinilbenzen je služil kot zamreževalec, 2-etilheksil akrilat je bil dodan kot snov za povečanje plastičnosti, kot iniciator smo uporabili kalijev peroksodisulfat, kot surfaktant pa Span 80. Zaradi spreminjanja viskoznosti emulzije smo dodali organsko topilo. Kot najustreznejšega smo izbrali klorobenzen. Spreminjali smo tako delež topila kot delež 2-etilheksil akrilata. Ob uporabi propelerskega mešala in reaktorske posode smo pri 300 obr/min dobili emulzijo z visokim deležem notranje faze, ki smo jo nanesli na stekleno ploščo in s povišano temperaturo sprožili polimerizacijo. Nastale so porozne poliHIPE membrane z debelinami od 60-100 %m. Pri membranah smo želeli doseči ustrezno gibljivost zaradi morebitnih zahtev aplikacij. Z dodatkom 2-etilheksil akrilata se je gibljivost membran bistveno izboljšala. V nadaljevanju smo spreminjali delež etilheksil akrilata, saj smo želeli preveriti njegov vpliv na termične lastnosti membran. Z infrardečo spektroskopijo smo preverili kemijsko strukturo membran. S termično analizo smo določili termične lastnosti membran v temperaturnem območju od 40 °C do 500 °C. Uporabili smo termični metodi termogravimetrijo in diferenčno dinamično kalorimetrijo. Ugotovili smo, da je pri vseh vzorcih opazna popolna izguba mase. Iz termogravimetrične krivulje je razvidna ena stopnja razpada, katerega temperaturno območje se giblje med 350°C in 470 °C. Z razpadom sovpada tudi temperatura tališča, ki je med 415 °C in 427 °C. Temperatura steklastega prehoda se nakazuje pri temperaturi okoli 45 °C. Vpliva 2-etilheksil akrilata na temperaturo steklastega prehoda nismo zaznali.

Keywords

kemija;polimeri;membrane;polimerizacija;emulzije;zamreženi polimeri;termične lastnosti;polistiren;diplomska dela;

Data

Language: Slovenian
Year of publishing:
Source: Maribor
Typology: 2.11 - Undergraduate Thesis
Organization: UM FNM - Faculty of Natural Sciences and Mathematics
Publisher: [U. Sevšek]
UDC: 54(043.2)
COBISS: 16175880 Link will open in a new window
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Downloads: 319
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Other data

Secondary language: English
Secondary title: PREPARATION OF POLYHIPE MEMBRANES AND CHARACTERISATION OF THEIR THERMAL PROPERTIES
Secondary abstract: orous polyHIPE membranes (5 % crosslinked) were prepared by the use of emulsion polymerisation. Styrene, divinylbenzene and 2-ethylhexyl acrylate were the monomers. Divinylbenzene was used as a crosslinker, while 2-ethylhexyl acrylate was added as a plasticizer, potassium persulfate was the initiator and Span 80 the surfactant. Due to the variation of viscosity of emulsions various organic solvents were added, and chlorobenzene gave the best results. Content of 2-ethylhexyl acrylate and the solvent was varied. By the use of an overhead propeller stirrer at 300 rpm high internal phase emulsion was produced, casted to a glass plate and cured thermically. Porous polyHIPE membranes with thicknesses between 60 and 100 % m were produced. Another goal was to obtain appropriate flexibility of the membranes because of different possible applications. The addition of 2-ethylhexyl acrylate substantially improved the flexibility of the membranes. Further more, the amount of added 2-ethylhexyl acrylate was varied in order to determine its influence on the thermal characteristics of the membranes. FTIR spectroscopy was used to confirm the chemistry of the membranes. By the use of thermal analysis the thermal characteristics were investigated in temperature range between 40 °C in 500 °C; thermogravimetry and differential scanning calorimetry were used. Full mass loss was found in all cases. From the thermogravimetric curve a one degree of decomposition is seen between 350 °C and 470 °C. Within this temperature range falls also the melting point (415 °C-427 °C). Glass transition temperature seems to be around 45 °C, while the effect of EHA on the glass transition temperature could not be determined.
Secondary keywords: polymers;polyHIPE;membranes;emulsion polymerisation;high internal phase emulsion;crosslinked polymers;thermal characteristisc of polymers;polystyrene;
URN: URN:SI:UM:
Type (COBISS): Undergraduate thesis
Thesis comment: Univ. v Mariboru, Fak. za naravoslovje in matematiko, Oddelek za kemijo
Pages: 50 f.
Keywords (UDC): mathematics;natural sciences;naravoslovne vede;matematika;chemistry;crystallography;mineralogy;kemija;
ID: 17551