Utjecaj nanočestica cinkova oksida na strukturu i svojstva mješavine poli(vinil-alkohola) i hitozana

doctoral thesis

• Title (english): Effect of zinc oxide nanoparticles on structure and properties of poly(vinyl-alcohol)/chitosan blend
• Author: Daniel Pugar
• Mentor: Tatjana Haramina (mentor)
• Committee member: Lidija Ćurković (predsjednik povjerenstva)
• Committee member: Zdravko Schauperl (član povjerenstva)
• Committee member: Jelena Macan (član povjerenstva)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2021-05-14, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering
• Universal decimal classification (UDC): 67/68 - Various industries, trades and crafts

Abstract

Nanokompoziti uključuju širok spektar materijala, koji se sastoje od više izrazito različitih komponenata, izmiješanih na nanometarskoj skali. Svojstva nanokompozita ne ovise samo o konstituentima, već i o morfologiji i karakteristikama na sučelju faza.
Istraživanje je provedeno na filmovima načinjenim od nanokompozita s antimikrobnim djelovanjem. U netoksičnu polimernu matricu od poli(vinil-alkohola) (PVA), topljivu u vodi, dodane su organske nanočestice hitozana (CS) i anorganske nanočestice cinkova oksida (ZnO) poznate po antimikrobnom učinku. Mješavine PVA i CS kemijski su umrežene glutaraldehidom (GA). Za karakterizaciju mješavina korištene su sljedeće tehnike: dinamičko-mehanička analiza (DMA), diferencijalna pretražna kalorimetrija (DSC), pretražna elektronska mikroskopija uz energijski razlučujuću rendgensku spektroskopiju (SEM/EDS), mikroskopija atomskih sila (AFM) te infracrvena spektroskopija s Fourierovom transformacijom (FTIR). Također, ispitan je i utjecaj nanočestica i umreženosti na permeaciju malih molekula dušika kroz dobivene nanokompozitne filmove. Permeacija je ispitana time-lag metodom.
Utvrđeno je da se dinamički modul elastičnosti i faktor prigušenja vibracija mogu krojiti variranjem udjela dodanih komponenata. Između PVA, CS i ZnO vidljiva je interakcija što omogućuje dobru mješljivost. Hitozan smanjuje stupanj kristalnosti PVA, a formiraju se vodikove veze između PVA i CS. Dodatkom ZnO u polimernu matricu smanjuje se intenzitet α relaksacije u mehaničkom spektru, što ukazuje na dobru povezanost i stvaranje međufaze slabije pokretljivosti na sučelju s polimernom matricom. Dodavanjem CS i ZnO u PVA poboljšavaju se barijerna svojstva.

Abstract (english)

Nanocomposites encompass a large variety of materials made of distinctly dissimilar components and mixed on a nanometer scale. Their properties depend not only on the properties of their constituents, but also on their morphology and interfacial characteristics.
This research was conducted on films made of nanocomposites with antimicrobial activity. Organic nanoparticles (NPs) of chitosan and inorganic nanoparticles of ZnO, both known for their antimicrobial effect are added into a water soluble non-toxic PVA matrix. Blends of PVA and CS were chemically crosslinked with glutaraldehyde (GA). Characterization of blends was performed using dynamic-mechanical analysis (DMA), differential scanning calorimetry (DSC), scanning electron microscopy with energy dispersive x-ray spectroscopy (SEM/EDS), atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR). The influence of nanoparticles and crosslinking on the permeation of small nitrogen molecules through the obtained nanocomposite films was also investigated. Permeation was examined by the time-lag method.
It was found that the dynamic modulus of elasticity and the vibration damping factor can be tailored by varying the proportion of added components. An interaction between PVA, CS and ZnO was confirmed, which allows good miscibility. Chitosan reduces crystallinity degree of PVA, and hydrogen bonds are formed between PVA and CS. The addition of ZnO to the polymer matrix reduces the intensity of α relaxation in the mechanical spectrum, which indicates a good connection and the formation of an interphase with reduced molecular mobility at the interface with the polymer matrix. The addition of CS and ZnO to PVA improves barrier properties.

• Keywords: Polimerne mješavine; polimerni nanokompoziti; poli(vinil-alkohol); hitozan; nanočestice ZnO; dinamičko-mehanička analiza; barijerna svojstva; time-lag metoda
• Keywords (english): Polymer blends; polymer nanocomposites; poly(vinyl-alcohol); chitosan; ZnO nanoparticles; dynamic mechanical analysis; barrier properties; time-lag method
• Language: croatian
• URN:NBN: urn:nbn:hr:235:134916
• Study programme: Title: Mechanical Engineering and Naval Architecture; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti, područje tehničkih znanosti (doktor/doktorica znanosti, područje tehničkih znanosti)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2021-06-15 08:03:35