Biokompoziti ojačani morskim školjkama za stomatološke primjene

master's thesis

• Title (english): Sea shell based biocomposites for dental applications
• Author: Elizabeta Žalac
• Mentor: Irena Žmak (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2015-12-04, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering

Abstract

Materijali za izradu dentalnih implantata moraju imati dobra mehanička i tribološka svojstva koja mogu podnijeti velike sile i naprezanja u usnoj šupljini koje mogu ići i do 1200 N. Međutim, upravo se mehanička i tribološka svojstva smatraju jednim od najvažnijih ograničavajućih faktora u primjeni. U radu su ispitivana mehanička i tribološka svojstva poli (metil-metakrilata) ili skraćeno PMMA kompozita ojačanog česticama morskih školjka. Načinjeno je 16 ispitnih uzoraka PMMA biokompozita s masenim udjelima čestica dviju vrsta školjaka u iznosu u 2 %, 6 %, 10 % i 14 %, te s veličinama čestica manjima od 50 µm te s veličinama čestica od 50 do 100 µm, a načinjen je i referentni uzorak koji se sastoji samo od PMMA s 0 % ojačanja, koji je služio za usporedbu rezultata.

Ispitivanja koja su se provodila na ispitnim uzorcima sastojala su se provjere mikrotvrdoće, otpornosti na trošenje, provjere tlačne čvrstoće te mikroskopiranja. Ispitivanje otpornosti na trošenje radilo se za 4 različita kuta trošenja i to 15°, 30°, 60° i 90°. Rezultati dobiveni ispitivanjem na trošenje pokazali su očekivanu najveću otpornost na ispitnim uzorcima s većim masenim udjelima čestica manjeg promjera, te najmanju otpornost na trošenje kod uzoraka s manjim masenim udjelima čestica većeg promjera. Rezultati mikroskopije pokazali su jednoličnu distribuciju sedimenta, bez naznaka aglomeracije. Ispitivanje mikrotvrdoće po Vickersu rezultiralo je manjom razlikom u povišenju mikrotvrdoće česticama ojačanih kompozita, a rezultati ispitivanja na tlačnu čvrstoću pokazali su neznatne promjene svojstava ispitnih uzoraka u odnosu na referentni. Razlog tome može biti premali udio čestica umetnutih u matricu kompozita. Ojačanje česticama morskih školjki, zbog njihovih izuzetnih svojstava doprinosi poboljšanju svojstava kompozita, a za to je potreban maseni udio veći od 10%.

Abstract (english)

Materials for production of dental implants must have mechanical and tribological characteristics that can endure heavy mouth forces, stress and strain, which can go up to 1200 N. However, mechanical and tribological characteristics are one of the most important limiting factors in application. In this work mechanical and tribological characteristics of Poly (Methyl- methacrylate) PMMA biocomposite strengthened by sea shells particles were tested. 16 tested PMMA biocomposites samples were made with 2 %, 6 %, 10 % and 14 % weight fraction for two types of sea shells with particle sizes less than 50 µm and with particle sizes from 50 to

100 µm. A referential sample that consists of only PMMA with 0 % reinforcement was also made and it was used for results comparison.

Research made on tested samples consisted of testing microhardness, wear test, compression test and microscopy. Wear test was made for four different wear angles (15°, 30°, 60° and 90°). Wear test results revealed expected highest resistance on tested samples with higher mass share of particles with smaller diameter, and lowest wear resistance on tested samples with lower mass share of particles with higher diameter. Microscopy results showed good, uniform dispersion of the particles inside biocomposite, without agglomeration warning. Microhardness test by Vickers showed a slight increase in hardness, while the compression test didn't show a significant difference in enhancing the compression properties of particulate reinforced biocomposite. The reason may be lower particle shares inserted in composite matrix. Sea shells particles are a good reinforcement material, and because of their exceptional characteristics they contribute to improvement of composite characteristics and in order to achieve that, weight content higher than 10 % is needed.

• Keywords: biokompoziti; PMMA; morske školjke; dentalni implantati
• Language: croatian
• URN:NBN: urn:nbn:hr:235:680672
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka strojarstva (magistar/magistra inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2019-05-22 15:11:41