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1.
Membranes from polysulfone/N,N-dimethylacetamide/water system
Vladimir Kaiser, Črtomir Stropnik, 2000, original scientific article

Abstract: Polymeric membranes were prepared by the wet-phase separation method from solutions of different contents of polysulfone in N,N-dimethylacetamide; solutions were cast in different thickness before immersion into the pure water coagulation bath. Two main processes take place during the formation of membranes: nucleation and growth of the polymer lean phase with subsequent solidification of the polymer rich phase, and the formation of channels, macrovoids and mega-macrovoids. By the first process a cellular structure is formed whilst the second process connects the cells by opening the space between them. The degree of interconnectedness is an additional factor that affects the pure water flux. By changing the cast solution compositions and/or their cast thickness the interconnectedness of the cells can be controlled.
Keywords: chemical technology, organic technology, polymer membranes, membrane preparation, wet phase inversion, polymers, polysulphon
Published: 18.08.2017; Views: 974; Downloads: 96
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2.
Ternarni sistem polisulfon-dimetilacetatamid : voda; formiranje membrane po mokrem postopku fazne inverzije
Vladimir Kaiser, Črtomir Stropnik, 1999, original scientific article

Abstract: Polisulfon je pomemben material za pripravo polimernih asimetričnih poroznih membran. Najširše uporabljen način njihove priprave je mokri postopek fazne inverzije ternanrnega sistema polisulfon/dimetilacetamid:voda (PSf/DMA:▫$H_2O$▫). Sistem PSf/DMA:▫$H_2O$▫ smo opazovali pri formiranju polisulfonske membrane v koagulacijski kopeli. Podobna opazovanja smo izvedli tudi v epruvetah tako, da smo dodajali netopilo (▫$H_2O$▫) v izhodno raztopino in obratno. Pridobljena spoznanja smo poskušali uporabiti pri pojasnjenvanju mehanizma nastanka polisulfonskih membran, ki jih razlagamo s "potmi sestave" v ternarnem faznem diagramu polimer/topilo:netopilo.
Keywords: polimerne asimetrične porozne membrane, polisulfon, mokra fazna inverzija, mehanizem nastanka
Published: 10.07.2015; Views: 2828; Downloads: 40
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3.
Strjevanje polimera v sistemu polisulfon/N,N-dimetilacetamid/voda in njegova morfološka raznolikost
Vladimir Kaiser, Črtomir Stropnik, 2000, original scientific article

Abstract: Preučevali smo mokro fazno inverzijo ternaranega sistema polisulfon/N,N-dimetilacetamid/voda (PSf/DMA/voda) z namenom, poglobiti razumevanje mehanizma nastajanja polimernih asimetričnih poroznih membran. Morfologije presekov membran smo preučevali z vrstično elektronsko mikroskopijo, sam proces fazne inverzije pa smo opazovali z merjenjem motnosti membranotvornega sistema med procesom nastajanja membrane. Spreminjanje vsebnosti polimera v raztopini (PSf/DMA) in debeline njenega nanosa povzroči v procesu mokre fazne inverzije poleg nastanka polimernega lateksa formiranje morfološko različnih membran. Nastanejo membrane s celično, dvozvezno in krogličasto zrnatao morfologijo. Njihov nastanek lahko predstavimo s "potmi sestave" v ternarnem faznem diagramu polimer/topilo/netopilo in pojasnimo z različnimi načini fazne inverzije.
Keywords: polisulfonske asimetrične porozne membrane, mokra fazna inverzija, načini fazne inverzije, morfologija
Published: 10.07.2015; Views: 997; Downloads: 67
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4.
Wet-phase-separation membranes from the polysulfone/N,N-dimethylacetamide/water ternary system: the formation and elements of their structure and properties
Črtomir Stropnik, Vladimir Kaiser, Vojko Musil, Milan Brumen, 2005, original scientific article

Abstract: Asymmetric and porous polysulfone (PSf) membranes were prepared by wet phase separation. Binary (PSf)/N,N-dimethylacetamide (DMA) solutions with polymer concentrations of 12.5-30 wt % were cast in thicknesses of 80-700 m and immersed in a coagulation bath of pure water. The morphology of the formed membranesć cross sections consisted of a cellular structure and macrovoidsč the cellular structure density was highest when the cast solution contained about 21 wt % PSf, regardless of the cast thickness. The membranesć pure waterpermeability decreased as the cast thickness increased. The instantaneousonset of the turbidity, regardless of the PSf content and cast thickness, its steep growth, and relatively high end value were the main characteristics of the turbidity phenomena taking place during the formation of the protomembranes. Again, the membrane-forming system with a PSf/DMA solution with about 21 wt % polymer, regardless of the cast thickness, had thehighest turbidity end value. The shrinkage of the cast solutions into the corresponding protomembrane was also examined quantitatively. Inverse experiments showed that the direction of the gravitation field had no influence on the shrinkage of the membrane-forming ternary system or the membranesć morphology and its water permeability.
Keywords: polymeric membranes, polysulfone asymmetric porous membranes, wet-phase separation, membrane preparation, morphology
Published: 01.06.2012; Views: 1494; Downloads: 72
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5.
Hidrolizne potenciometrične titracije v sistemu Ba2+ - CrO42- - SO42- : diplomsko delo
Vladimir Kaiser, 1993, undergraduate thesis

Keywords: titracije
Published: 26.07.2007; Views: 2043; Downloads: 0

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