Nanofluidi na osnovi grafena i biljnih estera

master's thesis

• Title (english): Nanofluids based on graphene and plant based esters
• Author: Leo Marić
• Mentor: Ante Jukić (mentor)
• Committee member: Ante Jukić (predsjednik povjerenstva)
• Committee member: Fabio Faraguna (član povjerenstva)
• Committee member: Ernest Meštrović (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2023-09-28, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering

Abstract

Cilj ovog rada je priprema nanofluida na osnovi repičinog ulja (RU) i metilnog estera masnih kiselina (Fatty acid methyl esters – FAME) in situ polimerizacijom monomera
metil-metakrilata, lauril-metakrilata i stearil-metakrilata uz dodatak nanočestica grafena pri izotermnim uvjetima od 95±1 °C u šaržnom kotlastom reaktoru tijekom 240 minuta. Polimerizacija je provedena uz dodatak peroksidnog inicijatora
tert-butil-peroksi-2-etilheksanoat. Nanofluidi su pripremljeni metodom u dva stupnja disperzijom čestica grafena u baznim uljima FAME i repičinom ulju ultrazvučnom homogenizacijom. Ukupno je pripremljeno 16 nanofluida raznih udjela grafena i polimera. Rezultati iz kojih se zaključuje kako dodatkom grafena nastaje polimer veće molekulske mase dobiveni su GPC analizom te određivanjem krivulja raspodjele molekulskih masa polimera bez dodatka i s dodatkom grafena. Iz 1H NMR spektara dobiveni su rezultati utjecaja grafena na povećanje konverzije polimerizacije. Ispitivanjem toplinske vodljivosti i električne otpornosti dobiveni su rezultati koji navode na povećanje toplinske vodljivosti i smanjenje volumne otpornosti nanofluida dodatkom grafena u odnosu na bazna ulja bez grafena. Nadalje, ispitivanjem reoloških svojstava pokazalo je utjecaj grafena i polimera na povećanje viskoznosti nanofluida i rezultate utjecaja grafena i polimera na koeficijente trenja i otpor maziva trošenju koji ne pokazuju trend rasta odnosno smanjenja. Stabilnost pripremljenih nanofluida ispitivana je vizualnim testom tijekom 42 dana kojim je utvrđena najveća stabilnost kod uzoraka s 10 mas. % udjelom polimera i dodanim česticama grafena. Analiza toplinskih tokova i faznih prijelaza razlikovnom pretražnom kalorimetrijom (DSC) utvrdila je smanjenje kristalizacije i snižavanje temperature početka kristalizacije kod svih uzoraka dodatkom grafena i polimera, a najveća razlika primijećena je kod nanofluida na osnovi FAME-a.

Abstract (english)

The goal of this work is the preparation of nanofluids based on rapeseed oil (RU) and fatty acid methyl esters (FAME) by in situ polymerization of methyl-methacrylate,
lauryl-methacrylate, and stearyl-methacrylate monomers with the addition of graphene nanoparticles under isothermal conditions of 95 ±1 °C in a batch boiler reactor for
240 minutes. The polymerization was carried out with the addition of the peroxide initiator, tert-butyl-peroxy-2-ethylhexanoate. Nanofluids were prepared by a two-step method by dispersion of graphene particles in FAME and rapeseed oil base oils by ultrasonic homogenization. A total of 16 nanofluids with various concentrations of graphene and polymers were prepared. The results from which it can be concluded that the addition of graphene creates a polymer with a higher molecular weight were obtained by GPC analysis and by determining the distribution curves of the polymer molecular masses without and with the addition of graphene. From the 1H NMR spectra, the results of the influence of graphene on the increase in polymerization conversion were obtained. By testing thermal conductivity and electrical resistance, results were obtained that indicate an increase in thermal conductivity and a decrease in volume resistance of nanofluids with the addition of graphene compared to base oils without graphene. Furthermore, the examination of rheological properties showed the influence of graphene and polymer on increasing the viscosity of nanofluids and the results of the influence of graphene and polymer on friction coefficients and wear resistance of lubricants, which do not show an increasing or decreasing trend. The stability of the prepared nanofluids was examined by a visual test for 42 days, which determined the highest stability in samples with 10 wt. % by polymer content and added graphene particles. The analysis of heat flows and phase transitions by differential scanning calorimetry (DSC) determined a reduction in the extent of crystallization and a lowering of the temperature of the beginning of crystallization in all samples with the addition of graphene and polymer, and the biggest difference was observed in nanofluids based on FAME.

• Keywords: polimerizacija; nanofluidi; biljni esteri; grafen; stabilnost; viskoznost; koeficijent trenja; toplinska vodljivost; kristalizacija
• Keywords (english): polymerization; nanofluids; plant based esters; graphene; stability; viscosity; coefficient of friction; thermal conductivity; crystallization
• Language: croatian
• URN:NBN: urn:nbn:hr:149:891345
• Study programme: Title: Environmental Engineering - Graduate study; Study programme type: university; Study level: graduate; Academic / professional title: sveučilišni/a magistar/magistra inženjer/inženjerka ekoinženjerstva (sveučilišni/a magistar/magistra inženjer/inženjerka ekoinženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Embargoed access; Embargo expiration date: 2025-10-01
• Created on: 2023-11-24 09:30:51