Poliamidni materijali za aditivnu proizvodnju

undergraduate thesis

• Title (english): Polyamide materials for additive manufacturing
• Author: Matija Brkić
• Mentor: Sanja Lučić Blagojević (mentor)
• Committee member: Sanja Lučić Blagojević (predsjednik povjerenstva)
• Committee member: Mirela Leskovac (član povjerenstva)
• Committee member: Domagoj Vrsaljko (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2019-09-17, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering

Abstract

U današnje vrijeme, napretkom tehnologije došlo je razvoja 3D pisača koji omogućuju tiskanje objekata bez naknadne obrade. Materijal koji se najčešće koristi za 3D tiskanje je prah poliamida 12 (PA 12). Cilj ovog rada bio je ispitati utjecaj SLS procesa na strukturu i svojstva PA 12. Analizirane su tri generacije PA 12 praha: uzorci novog praha, uzorci praha koji je dva puta prošao ciklus SLS procesa te uzorak otpadnog praha. Nadalje uzorci prahova su pretaljeni u Brabenderu kako bi se istražila moguća daljnja upotreba otpadnog praha. Toplinska svojstva uzoraka ispitana su diferencijalnom pretražnom kalorimetrijom (DSC), a toplinska stabilnost termogravimetrijskom analizom (TGA). Mehanička svojstva određena su testom jednoosnog istezanja, a raspodjela veličina čestica ispitivanih uzoraka laserskom difrakcijom. Rezultati DSC analize pokazali su da povećanjem broja korištenja praha dolazi do smanjenja uređenosti kristalne strukture što je posljedica taljenja jednog dijela kristalnih lamela uslijed visokih temperatura u SLS procesu. Također, pretaljivanjem se djelomično gubi uređenost kristalne strukture i znatno smanjuje udio kristalne faze u uzorku. TGA analiza ukazuje na smanjenje početne toplinske stabilnosti, a povećanje stabilnosti na kraju razgradnje ispitivanih uzoraka praha što je PA prah prošao više ciklusa 3D tiskanja. Isti trend je zabilježen i kod pretaljenih uzoraka. Testom jednoosnog istezanja nisu zabilježene značajnije promjene u vrijednostima naprezanja i istezanja u točki popuštanja, ali se s povećanjem broja ciklusa SLS-a vrijednosti sekantnog modula povećavaju. Rasipanje vrijednosti prekidnog naprezanja i istezanja predstavljaju ozbiljno ograničenje korištenja otpadnog praha za druge primjene.

Abstract (english)

Nowadays, advancement in techonoly brought development of 3D printers which allows printing the object without additional processing. Material which is used the most in 3D printing is powder of Polyamide 12 (PA 12). Purpose of this work is to examine influence of SLS process on structure and properties of PA 12 powder. Three generations of PA 12 powder were analyzed: samples of virgin powder, samples which were used two times in SLS process and samples of waste powder. Furthermore, powder samples were pre-melted in Brabender to investigate the possible further use of waste powder. Thermal properties of samples were determined by differential scanning calorimetry (DSC), and thermal stability by thermogravimetric analysis (TGA). Mechanical properties were determined by tensile test and particle size distribution of powder by laser diffraction. The results of the DSC analysis showed that by increasing the number of SLS cycles, the arrangement of the crystal structure in powder decreases, which is a consequence of the melting of one part of the crystal lamellae due to the high temperatures in the SLS process. Also, with melting there is partial lost of the crystalline structure arrangement and significant reduction in degree of crystallinity. TGA analysis showed decreasing in initial thermal stability, but increasing stability at the end of degradation for examined powder samples as PA powder has undergone multiple cycle of 3D printing. Same trend is also in samples which were pre-melted. Tensile test indicated that there was not significant changes of strain and elongation in yield point, but with increasing number of SLS cycles of process there is increase of secant modulus. Dissipation of values for strain and elongation at break presents major limit for using waste powder in for further applications.

• Keywords: Poliamid 12; SLS proces; toplinska svojstva; toplinska stabilnost; mehanička svojstva; raspodjela veličina čestica
• Keywords (english): Polyamide 12; SLS process; thermal properties; thermal stability; mechanical properties; particle size distibution
• Language: croatian
• URN:NBN: urn:nbn:hr:149:258241
• Study programme: Title: Materials Science and Engineering - Undergraduate study; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka kemijskog inženjerstva (sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka kemijskog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2023-02-14 08:38:07