Utjecaj titanijevog dioksida na toplinska, mehanička i barijerna svojstva poli(3-hidroksibutirat-ko-3-hidroksivalerata)

master's thesis

• Title (english): The influence of titanium dioxide on the thermal, mechanical and barrier properties of poly(3- hydroxybutyrate-co-3-hydroxyvalerate)
• Author: Ema Čemerika
• Mentor: Vesna Ocelić Bulatović (mentor)
• Committee member: Vesna Ocelić Bulatović (predsjednik povjerenstva)
• Committee member: Dajana Kučić Grgić (član povjerenstva)
• Committee member: Iva Movre Šapić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2024-09-13, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering

Abstract

Rastuća zabrinutost za očuvanje okoliša i smanjenje onečišćenja dovela je do sve većih izazova u razvoju i istraživanju prihvatljivih materijala. U ovom radu pripremljeni su nanokompoziti na bazi poli(3-hidroksibutirat-ko-3-hidroksivalerata) (PHBV) kao polimerne matrice i nanočestica titanova dioksida (TiO2) kao punila. PHBV je netoksičan polimer s visokim stupnjem kristalnosti, otporan je na ultraljubičasto zračenje, biokompatibilan je i biorazgradiv. S druge strane karakteriziraju ga slabija mehanička svojstva, izrazito je krut i krt. Iz tog razloga se PHBV-u dodaju nanočestice TiO2, koje doprinose poboljšanju mehaničkih svojstava, poput čvrstoće i elastičnosti te utječu na povećanje toplinske stabilnosti. Da bi se odredila svojstva nanokompozita kao potencijalnih materijala za industriju pakiranja hrane, provedena su ispitivanja na PHBV/TiO2 nanokompozitima s različitim udjelima TiO2 (1, 3, 5, 7 i 10 mas. %) te na čistoj PHBV matrici. Nanokompoziti su pripravljeni miješanjem u Brabender gnjetalici i prešanjem na hidrauličkoj preši. Toplinska svojstva ispitana su diferencijalnom pretražnom kalorimetrijom (DSC) i termogravimetrijskom analizom (TGA). Morfologija uzoraka određena je pretražnim elektronskim mikroskopom s disperzivnom rendgenskom spektroskopijom (SEM-EDX). Infracrvena spektroskopija s Fourierovim transformacijama i prigušenom totalnom refleksijom (FTIR-ATR) korištena je za određivanje vibracija funkcionalnih skupina. Mjerenjem kontaktnog kuta dobivene su informacije o slobodnoj površinskoj energiji, dok su mehanička svojstva ispitana mehaničkom kidalicom. Propusnost vodene pare određena je aparaturom po Herfeldu. Rezultati istraživanja su pokazali da TiO2 nanočestice utječu na fazne prijelaze PHBV matrice, smanjujući temperaturu taljenja i temperaturu kristalizacije, te povećavaju toplinsku stabilnost. Morfologija površina nanokompozita pokazuje ravnomjernu raspodjelu nanočestica. FTIR spektri pokazuju vibracije karakteristične za PHBV matricu i Ti-O-Ti veze. Izmjerene vrijednosti kontaktnih kutova pokazuju povećanje hidrofilnosti nanokompozita pri udjelu TiO2 većim od 5 mas. %. Povećanjem udjela TiO2 smanjuje se propusnost vodene pare te prekidna čvrstoća, prekidno istezanje i Youngov modul, ukazujući na lošija mehanička svojstva nanokompozita u odnosu na čistu PHBV matricu.

Abstract (english)

The increasing concern for environmental preservation and pollution reduction has led togrowing challenges in the development and research of sustainable materials. In this study, nanocomposites based on poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) as the polymer matrix and titanium dioxide (TiO2) nanoparticles as the filler were prepared. PHBV is a non-toxic polymer with a high degree of crystallinity, resistant to ultraviolet radiation, and is both biocompatible and biodegradable. However, it is characterized by weaker mechanical properties and is extremely rigid and brittle. Therefore, TiO2 nanoparticles are added to PHBV to improve its mechanical properties, such as strength and elasticity, and to enhance its thermal stability. To determine the properties of nanocomposites as potential materials for the food packaging industry, tests were conducted on PHBV/TiO2 nanocomposites with different TiO2 contents (1, 3, 5, 7, and 10 wt. %) as well as on pure PHBV matrix.
The nanocomposites were prepared by mixing in a Brabender kneader and pressing on a hydraulic press. Thermal properties were examined using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The morphology of the samples was determined using a scanning electron microscope with energy dispersive X-ray spectroscopy (SEM-EDX). Fourier transform infrared spectroscopy with attenuated total reflectance
(FTIR-ATR) analyzed the vibrations of functional groups. Contact angle measurements provided information about the free surface energy, while mechanical properties were tested using a mechanical tester. Water vapor permeability was determined using Herfeld equipment. The results showed that TiO2 nanoparticles influence the phase transitions of the PHBV matrix, reducing the melting temperature and the crystallization temperature, as well as enhancing thermal stability. The morphology of the nanocomposite surfaces shows a uniform distribution of nanoparticles. FTIR spectra reveal vibrations characteristic of the PHBV matrix and Ti-O-Ti bonds. The measured contact angle values indicate an increase in nanocomposite hydrophilicity with TiO2 content greater than 5 wt. %. Increasing TiO2 content decreases water vapor permeability, tensile strenght, elongation at break and Young's modulus, indicating poorer mechanical properties of the nanocomposites compared to the pure PHBV matrix.

• Keywords: nanokompoziti; poli(3-hidroksibutirat-ko-3-hidroksivalerat) (PHBV); titanov dioksid (TiO2); ambalaža za pakiranje hrane
• Keywords (english): nanocomposites; poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV); titanium dioxide (TiO2); food packaging
• Language: croatian
• URN:NBN: urn:nbn:hr:149:657197
• Project: Number: NPOO.C3.2.R3-I1.04.0059; Title: Proizvodnja i razvoj kompostabilne ambalaže iz otpadne biomase za pakiranje industrijski prerađenih prehrambenih proizvoda; Title: Production and development of compostable packaging from waste biomass for the packaging of industrially processed food products; Leader: Dajana Kučić Grgić; Jurisdiction: Croatia; Funder: Ministarstvo znanosti, obrazovanja i mladih Republike Hrvatske
• Study programme: Title: Applied Chemistry - Graduate study; specializations in: Environmental chemistry and green technologies, Advanced materials and technologies, Applied organic chemistry; Course: Environmental chemistry and green technologies; Study programme type: university; Study level: graduate; Academic / professional title: sveučilišni/a magistar/magistra primijenjene kemije (sveučilišni/a magistar/magistra primijenjene kemije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2024-09-24 12:40:22