Priprava i karakterizacija nanofluida za balističke tekuće oklope

master's thesis

• Title (english): Preparation and characterization of nanofluids for ballistic liquid armor
• Author: Tina Zubović
• Mentor: Ante Jukić (mentor)
• Committee member: Ante Jukić (predsjednik povjerenstva)
• Committee member: Marijana Kraljić Roković (član povjerenstva)
• Committee member: Fabio Faraguna (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2021-09-27, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering

Abstract

U industrijskom sektoru te u istraživanju i razvoju novih kemijsko-industrijskih tehnologija, pojam nanofluidi poznat je tek nekoliko desetljeća. Intenzivno istraživanje nanofluida pokazalo se izuzetno produktivnim te se ono nastavlja otkrivajući nova svojstva ovih sustava koji nadograđuju sadašnju tehnologiju. Istraživanja se pretežito usmjeravaju na rashladne sustave zbog povećane toplinske vodljivosti koje karakteriziraju nanofluide, no u posljednje vrijeme pažnja je usmjerena na uporabu nanofluida i u balističkoj zaštiti. Sustavi koji su trenutno istraživani kao učinkoviti sustavi za balističku zaštitu temeljeni su na polietilen glikolu (PEG) te se teži pronalasku ekonomski prihvatljivijih rješenja. Cilj ovog rada bila je priprema i karakterizacija nanofluida čiji su bazni fluid polialfaolefinska ulja različitih viskoznosti i različitih sastava (PAO4, PAO6, PAO8), a kao punilo koristile su se nanočestice SiO2. Nanofluidi su pripravljeni s 0,5; 1,0; 2,5; 5,0; 7,5 i 10 mas. % SiO2. Istražen je utjecaj vrste baznog fluida i koncentracije nanočestica na toplinsku vodljivost, električnu provodnost, stabilnost te reološka svojstva pripremljenih nanofluida. Istraživanje je pokazalo da su pripremljeni nanofluidi Newtonovi fluidi s niskim dielektričnim konstantama. Ispitivanje toplinske vodljivosti pokazalo je da dodatkom nanočestica u bazni fluid dolazi do porasta toplinske vodljivosti nanofluida. Povećanjem temperature i smanjenjem koncentracije SiO2 u nanofluidu smanjuje se viskoznost. Ispitivanje stabilnosti pripremljenih nanofluida pokazalo je da se radi o razmjerno stabilnim sustavima, dok je najveća stabilnost zabilježena za nanofluide s baznim fluidom najveće viskoznosti, PAO8.

Abstract (english)

In the industrial sector and in the research and development of new chemical-industrial technologies, the term nanofluids has been used for only a few decades. Intensive nanofluid research has proven to be extremely productive and it continues to reveal new features of these systems that build on current technology. Research is mainly focused on cooling systems due to the increased thermal conductivity characterized by nanofluids, but recently attention has been focused on the use of nanofluids in ballistic protection. The systems currently being investigated as effective ballistic protection systems are based on polyethylene glycol (PEG) and attempts are being made to find more economically viable alternatives. The aim of this work was the preparation and characterization of nanofluids whose base fluid were polyalphaolefin oils of different viscosities and different compositions (PAO4, PAO6, PAO8), and the filler were SiO2 nanoparticles. Nanofluids were prepared 0.5; 1.0; 2.5; 5.0; 7.5 and 10 wt. % SiO2. The influence of base fluid types and concetration of nanoparticles on thermal conductivity, electrical conductivity, stability and rheological properties of prepared nanofluids were investigated. The study showed that the prepared nanofluids were Newtonian fluids with low dielectric constants. Thermal conductivity testing showed that the addition of nanoparticles to the base fluid increases the thermal conductivity of nanofluids. As the temperature increases and the SiO2 concentration in nanofluid decreases, the viscosity decreases. Prepared nanofluids showed that they are relatively stable systems, while the highest stability was recorded for nanofluids with a base fluid of the highest viscosity, PAO8.

• Keywords: nanofluid; polialfaolefin (PAO); silicijev dioksid (SiO2); toplinska vodljivost; stabilnost; reološka svojstva; dielektrična konstanta
• Keywords (english): nanofluid; polyalphaolefin (PAO); silicon dioxide (SiO2); thermal conductivity; stability; rheological properties; dielectric constant
• Language: croatian
• URN:NBN: urn:nbn:hr:149:263529
• Study programme: Title: Applied Chemistry - Graduate study; specializations in: Environmental chemistry and green technologies, Advanced materials and technologies, Applied organic chemistry; Course: Advanced materials and technologies; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra primijenjene kemije (magistar/magistra primijenjene kemije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Access restricted to students and staff of home institution
• Created on: 2023-04-19 13:12:51