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Title:ŠTUDIJ PREDOBDELAVE IN OPLAŠČANJA REGENERIRANIH CELULOZNIH VLAKEN Z NANO DELCI
Authors:ID Hribernik, Silvo (Author)
ID Sfiligoj Smole, Majda (Mentor) More about this mentor... New window
ID Stana-Kleinschek, Karin (Comentor)
Files:.pdf DR_Hribernik_Silvo_2010.pdf (9,84 MB)
MD5: 41E44962915238C10394308CD019A986
PID: 20.500.12556/dkum/8244eeca-6840-476d-9c2a-34fba5abaf1d
 
Language:Slovenian
Work type:Dissertation
Organization:FS - Faculty of Mechanical Engineering
Abstract:Cilj naloge ''Študij predobdelave in oplaščanja regeneriranih celuloznih vlaken z nano delci'' je razvoj postopkov za oplaščanje celuloznih vlaken s funkcionalnimi nano delci, ki bi obstoječemu naboru lastnosti teh materialov dodali nove. Uporabili smo viskozna vlakna, ki smo jih oplaščali z delci silicijevega dioksida (SiO2) in železovega oksida-magnetita (Fe3O4). Raziskava je bila razdeljena v tri dele; predobdelava viskoznih vlaken z namenom aktivacije njihove površine ter povečanja pornega sistema s čimer izboljšamo adhezijo delcev in omogočimo njihovo rast v notranjosti vlaken. V drugem delu smo raziskali sintezo delcev magnetita ter lastnosti nastalih delcev; sintezne postopke smo primerjali z vidika njihove primernosti v kombinaciji s celuloznimi substrati. Tretji del je zajemal oplaščanje vlaken z delci silicijevega dioksida in magnetita po različnih postopkih. Z nabrekanjem v vodnih raztopinah natrijevega hidroksida različnih koncentracij smo odprli strukturo vlaken, s postopki sušenja z zamrzovanjem (liofilizacija) pa smo to povečanje pornega sistema ohranili, v primerjavi s sušenjem na zraku ali pri povišanih temperaturah. Raziskali smo vpliv postopkov predobdelav na nadmolekulsko strukturo vlaken, povečanje njihovega pornega sistema, na elektrokinetične lastnosti (površinski potencial) ter mehanske lastnosti. Povečanje deleža por je odvisno od uporabljene koncentracije natrijevega hidroksida in postopka zamrzovanja; višje koncentracije so v tem pogledu bolj učinkovite, vendar povzročajo znatnejše poslabšanje mehanskih lastnosti vlaken. Za nadaljnje postopke oplaščanja smo uporabili vlakna, nabrekana v 5 ut.% NaOH, ki smo jih počasi zamrzovali in liofilizirali. Podrobna raziskava sinteze delcev magnetita je zajemala variiranje molarnih koncentracij raztopin prekurzorjev ter njihovih razmerij, ter načina dodajanja komponent v reakcijski sistem. Spremljanje poteka reakcij in nastanka magnetita v posameznih fazah dodajanja reagentov oz. v določenih pH področjih ter analiza magnetnih lastnosti nastalih delcev je bila osnova za izbiro postopkov za kasnejše oplaščanje celuloznih vlaken. Koloidne lastnosti pripravljenih disperzij magnetita so bile raziskane s stališča njihove elektroforetične mobilnosti in velikosti delcev. Oplaščanje regeneriranih celuloznih vlaken z nano delci je potekalo po postopku in situ formacije delcev na površini vlaken za oba sistema delcev ter v primeru magnetita tudi z adsorpcijo delcev iz predhodno pripravljene disperzije. Aktivirana površina liofiliziranih vlaken diktira nastanek homogenih in gostejših plasti nano delcev v primerjavi z neenakomerno pokritimi površinami in aglomerati na zraku sušenih vlaken oz. vlaken brez predhodnega nabrekanja. Postopek liofilizacije pa omogoča v primeru delcev silicijevega oksida tudi njihovo rast v notranjosti vlaken. Lastnosti pripravljenih kompozitnih vlaken (viskozna vlakna z nano delci), ki so posledica anorganske faze, so v veliki meri izrazitejše v primeru liofiliziranih vlaken; stopnja zaščite proti vnetju vlaken in posledičnem temperaturnem razpadu, ki jo dajejo delci silicijevega dioksida ter vrednosti nasičene magnetizacije, ki jo prispevajo delci magnetita so višje pri vlaknih, ki smo jih pred nanosom delcev liofilizirali.
Keywords:regenerirana celulozna vlakna, alkalna predobdelava, nabrekanje, sušenje, liofilizacija, struktura, WAXS, SAXS, vrstična elektronska mikroskopija, elektrokinetične lastnosti, mehanske lastnosti, sinteza delcev, lastnosti koloidnih sistemov, oplaščanje vlaken, magnetne lastnosti, termične lastnosti
Place of publishing:[Maribor
Publisher:S. Hribernik]
Year of publishing:2010
PID:20.500.12556/DKUM-14958 New window
UDC:677.463.017:544.722.12(043.3)
COBISS.SI-ID:252288256 New window
NUK URN:URN:SI:UM:DK:LNUFI6NJ
Publication date in DKUM:27.08.2010
Views:4410
Downloads:446
Metadata:XML DC-XML DC-RDF
Categories:KTFMB - FS
:
HRIBERNIK, Silvo, 2010, ŠTUDIJ PREDOBDELAVE IN OPLAŠČANJA REGENERIRANIH CELULOZNIH VLAKEN Z NANO DELCI [online]. Doctoral dissertation. Maribor : S. Hribernik. [Accessed 4 April 2025]. Retrieved from: https://dk.um.si/IzpisGradiva.php?lang=eng&id=14958
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Secondary language

Language:English
Title:STUDY OF PRE-TREATMENT AND COATING OF REGENERATED CELLULOSE FIBRES WITH NANO PARTICLES
Abstract:Aim of the presented thesis is a development of procedures for coating of regenerated cellulose fibres with functional nano particles, which can add new properties to these fibres. We have used viscose fibres, which were coated with silicon dioxide particles (SiO2) and iron oxide-magnetite particles (Fe3O4). Research work was divided into three parts; pre-treatment of viscose fibres with an aim to activate their surface and to enlarge their pore system, which would enhance the adhesion of particles to the fibres’ surface and allow them to also grow in the inside of fibres. Second part is concerned with the magnetite particles’ synthesis and their properties; synthesis procedures were compared from the viewpoint of their suitability to be combined with cellulose fibres. Third part deals with the coating of fibres with silicon dioxide and iron oxide-magnetite particles with different procedures. Swelling of fibres in aqueous solutions of sodium hydroxide opens their fibrillar structure, while freezing and freeze-drying retains this enlargement of the pore system, in contrast with conventional air or elevated temperature drying. Effect of different pre-treatment procedures on fibres’ supramolecular structure, enlargement of their pore system, surface potential and mechanical properties was investigated. Degree of enhancement of the pore system depends on the used concentration of sodium hydroxide and type of freezing; higher alkali concentrations are more effective, but at a cost of extensive decrease of mechanical properties’ values. For coating with nano particles, fibres, swollen in 5 w.% NaOH and slowly frozen prior to freeze-drying, were used. Analysis of magnetite particles’ synthesis comprised of variations of molar concentrations of precursor solutions as well as different addition protocols of reactants into the reaction system. Following the synthesis and evolution of particles’ formation in different stages of synthesis procedure i.e. at different pH values and analysis of particles’ properties was basis for choosing the synthesis routes for subsequent coatings of fibres. Colloidal properties of prepared dispersions were investigated from a viewpoint of particles’ electrophoretic mobility and their sizes. Coating of fibres was carried out with an in situ formation of particles in presence of fibres and in the case of magnetite, also with an adsorption of particles from a pre-prepared dispersion. Activated surface of viscose fibres dictates the formation of surface layers of particles; homogenous and densely packed layers are formed, while air-dried fibres exhibit unevenly covered surfaces and aggregates of particles. Freeze-dried fibres also enable, in the case of silicon dioxide, their growth in the interior of fibres. Properties of prepared composite fibres (viscose fibres with nano particles), which result from the presence of inorganic phase, are more pronounced with freeze-drying pre-treatment; degree of combustion prevention and subsequent temperature degradation, which is yielded with silica particles and saturation magnetization values, contributed by magnetite particles.
Keywords:regenerated cellulose fibres, alkaline pre-treatment, swelling, drying, freeze-drying, structure, WAXS, SAXS, scanning electron microscopy, electrokinetical properties, mechanical properties, particle synthesis, properties of colloid systems, coating of fibres, magnetic properties, thermal properties


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