magistrsko delo
Petra Markovič (Author), Aleš Ručigaj (Mentor), Marjan Marinšek (Thesis defence commission member), Urška Šebenik (Thesis defence commission member)

Abstract

Polimeri in polimerni kompoziti so daleč najbolj raziskan razred materialov v okviru materialov s sposobnostjo samoceljenja. Zaradi velike porabe fosilnih goriv so številne raziskave usmerjene k iskanju in sintetiziranju polimerov iz bio-osnovanih virov z namenom, da bi nadomestili polimere na osnovi fosilnih goriv. Benzoksazine sintetiziramo z reakcijo med fenolnim in aminskim delom ter paraformaldehidom. Polimeri s sposobnostjo samoceljenja so zamreženi sistemi. Za izvedbo reakcij samoceljenja mora biti mreža takšnega materiala dovolj fleksibilna in s primernimi funkcionalnimi skupinami. Pri eksperimentalnem delu sem sintetizirala dva benzoksazinska monomera. Prvi je bil na osnovi difenolne kisline, stearilamina in paraformaldehida (DK/SA-BOX), drugi pa na osnovi difenolne kisline, Jeffamina D-2000 in paraformaldehida (DK/JF2000-BOX). Za preučevanje učinkovitosti samoceljenja kopolimerov iz bio-osnovanih virov sem s polimerizacijo z odpiranjem obroča pri visokih temperaturah pripravila kopolimere v petih različnih masnih razmerjih. Kemijsko strukturo in uspešnost sinteze sem potrdila z nuklearno magnetno resonanco (NMR). Pri obeh čistih benzoksazinskih monomerih sta bila na spektru vidna vrhova, s katerima sem uspešno potrdila nastanek oksazinskega obroča. Termične lastnosti čistih benzoksazinov in kopolimerov sem pridobila z diferenčno dinamično kalorimetrijo (DSC) in termomehanske lastnosti z dinamično mehansko analizo (DMA). Za vsak kopolimer sem s pomočjo programa STAR določila temperaturo steklastega prehoda Tg. Samoceljenje kopolimerov je potekalo pri temperaturi Tg + 10 °C. Učinkovitost samoceljenja sem uspešno dokazala z nateznimi testi lomne žilavosti. Vsak kopolimer in njegovo paralelko sem zlomila štirikrat, trikrat pa je poteklo samoceljenje. Najvišjo učinkovitost samoceljenja je pričakovano dosegel kopolimer, ki je vseboval 50 ut. % monomera DK/SA-BOX in 50 ut. % monomera DK/JF2000-BOX oziroma vzorec 50:50.

Keywords

benzoksazini;polimerizacija;polibenzoksazin;bio-osnovani viri;termične lastnosti;samoceljenje;temperatura steklastega prehoda;magistrska dela;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UL FKKT - Faculty of Chemistry and Chemical Technology
Publisher: [P. Markovič]
UDC: 678.7(043.2)
COBISS: 42001155 Link will open in a new window
Views: 292
Downloads: 63
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Other data

Secondary language: English
Secondary title: Thermally assisted self-healing of bio-based polybenzoxazines
Secondary abstract: By far the most researched class of materials with self-healing ability are polymers and polymer composites. Due to the high consumption of fossil fuels, numerous studies are focused on the synthesis of polymers from renewable resources in order to replace fossil fuel based polymers. Benzoxazines can be synthesized by reaction between phenol, amine and paraformaldehyde. Polymers with self-healing ability are cross-linked systems. The network of such material must be flexible enough to carry out self-healing reactions and must have suitable functional groups. In experimental work, two benzoxazine monomers were synthesized. The first one based on diphenolic acid, stearylamine and paraformaldehyde (DK/SA-BOX) and the second one based on diphenolic acid, Jeffamine D-2000 and paraformaldehyde (DK/JF2000-BOX). Copolymers were prepaired by ring-opening polymerization at high temperatures in five different weight ratios, to study the self-healing ability of copolymers from bio-based resources. Their chemical structure and synthesis success were confirmed with nuclear magnetic resonance (NMR). On both pure benzoxazine monomers spectrum were visible peaks which confirmed the formation of the oxazine ring. Thermal properties of pure benzoxazines and copolymers were obtained by differential dynamic calorimetry (DSC) and thermo-mechanical properties by dynamic mechanical analysis (DMA). For each copolymer, the glass transition temperature, Tg, was determined using the STAR program. Self-healing of the copolymers took place at a temperature of Tg + 10 °C. The effectiveness of self-healing has been successfully demonstrated by tensile fracture toughness tests. Each copolymer and its parallel was broken four times and self-healing took place three times. The highest self-healing efficiency was expected to be achieved by a copolymer containing 50 wt. % monomer DK/SA-BOX in 50 wt. % monomer DK/JF2000-BOX (sample 50:50).
Secondary keywords: polybenzoxazine;bio-based sources;thermal properties;self-healing;
Type (COBISS): Master's thesis/paper
Study programme: 1000376
Thesis comment: Univ. v Ljubljani, Fak. za kemijo in kemijsko tehnologijo, smer Kemijsko inženirstvo
Pages: 59 str.
ID: 12238189