<p>Sintetisane su klasične alkidne smole polazeći od ricinolne kiseline, anhidrida ftalne<br />kiseline i tri poliola (glicerina, trimetilolpropana i etoksilovanog pentaeritritola), kao i<br />hiperrazgranati alkidi na osnovu ditrimetilolpropana, dimetilolpropionske kiseline i<br />ricinolne kiseline. Smole su karakterisane određivanjem hidroksilnog i kiselinskog broja,<br />viskoznosti, srednjih molskih masa i njihove raspodele. Struktura sintetisanih smola je<br />potvrđena infracrvenom spektroskopijom sa Furijeovom transformacijom (FTIR).<br />Sintetisani alkidi imaju veliki sadržaj hidroksilnih grupa, a mali kiselinski broj. Prisustvo<br />hidroksilnih grupa, kao krajnjih funkcionalnih grupa, omogućuje modifikaciju alkidnih<br />smola i dobijanje materijala različitih svojstava. Sintetisani alkidi su umrežavani sa<br />triizobutoksimetil i heksametoksimetil melaminskom smolom u cilju dobijanja umreženog materijala željene strukture i svojstava za primenu u premazima. Umrežavanje smeša smola praćeno je FTIR spektroskopijom, dinamičko skanirajućom kalorimetrijom (DSC), reometrijom, kao i određivanjem sadržaja gela. Ispitivana su toplotna svojstva, dinamičkomehaničko ponašanje, fizičko-mehaničke karakteristike i hemijska otpornost filmova premaza. Umrežavanje smeša smola teče uglavnom preko hidroksilnih i karboksilnih grupa alkida sa izobutoksimetil i metoksimetil grupama u melaminskim smolama. Sintetisane klasične alkidne smole u smeši sa melaminskim smolama umrežavaju u temperaturnom opsegu od 90 do 170 <sup>0</sup>C, a hiperrazgranati alkidi od 80 do 170 <sup>0</sup>C, što su uobičajene temperature u tehnologiji lakova koji umrežavaju “pečenjem“. Umreženi filmovi premaza su toplotno veoma stabilni, budući da početak razgradnje premaza započinje na temperaturama od 281 do 330 <sup>0</sup>C. Potvrđeno je da postoji linearna zavisnost između modula izgubljene energije na 25 <sup>0</sup>C, koji je mera viskoznog odgovora materijala, i tvrdoće premaza određene metodom klatna. Svi projektovani premazi, bez obzira na nesavršenost nastale polimerne mreže, su pokazali zadovoljavajuća svojstva. Najbolja svojstva od klasičnih alkidnih premaza ima onaj na osnovu smeše alkida sa etoksilovanim pentaeritritolom i heksametoksimetil melaminske smole. Korišćenje hiperrazgranatih alkidnih smola kao veziva u ekološki prihvatljivim premazima ima prednost zbog manjeg sadržaja organskih rastvarača i manje viskoznosti u odnosu na klasične smole. Pretpostavljeno je da bi smeše sintetisanih klasičnih i hiperrazgranatih alkida sa melaminskim smolama (maseni odnos 70:30) bile pogodne za primenu u industriji boja i lakova. Potvrđeno je da su sistemi alkid/melaminska smola veoma složeni. Dobijeni rezultati omogućuju da se objasni uticaj građe prekursora na strukturu nastale polimerne mreže, a time i na svojstva premaza.</p> / <p>Conventional alkyd resins based on ricinoleic acid, phthalic anhydride and three polyols (glycerin, trimethylolpropane or ethoxylated pentaerythritol), as well as hyperbranched alkyds based on ditrimethylolpropane, dimethylol propionic acid and ricinoleic acid were synthesized. Prepared alkyds were characterized by the determination of hydroxyl and acid numbers, viscosity, average molecular masses and molecular masses distribution. The structure of synthesized resins is confirmed by Fourier Transform Infrared Spectroscopy (FTIR). Obtained alkyd resins have high content of hydroxyl groups and low acid number. The presence of hydroxyl groups as functional end groups opens up a high potential for further chemical modifications and for obtaining materials with different properties. Synthesized alkyds were cured by triisobutoxymethyl- and hexamethoxymethyl melamine resins, in order to obtain crosslinked material with desired structure and properties for coating applications. Curing of the resin mixtures were examined by FTIR spectroscopy, dynamic scanning calorimety (DSC), rheometry and by the determination of gel content. Thermal properties, dynamic mechanical behavior, physico-mechanical characteristics and chemical resistance of coated films were determined. Curing of the resin mixtures proceeds via the reactions between hydroxyl and carboxyl groups of alkyds with isobutoxymethyl and metoxymethyl groups in melamine resins. Synthesized alkyd/melamine resin mixtures became cured in the temperature range from 80 to 170 0C, which is the usual temperature range employed in the baking enamel technology. Cured films are thermally very stable since the onset of films degradation starts at high temperatures (from 281 to 330 0C). It is confirmed that there is a linear dependence between the loss modulus at 25 0C, which is the measure of the material viscosity response, and the coating hardness determined by pendulum method. All projected coatings, despite of defects in the resulting polymer networks, show satisfying properties. Among the conventional systems coating based on mixture of alkyd with ethoxylated pentaerythritol and hexamethoxymethyl melamine resin show the best properties. Application of hyperbranched alkyd resins, as binders in environment friendly coatings has an advantage due to less content of organic solvent and lower viscosity, compared to conventional alkyd resins. It is supposed that the combination of synthesized conventional and hyperbranched alkyds with melamine resins (weight ratio of 70:30 based on dried mass) could be employed as new materials for the industrial preparation of baking enamels. It is confirmed that alkyd/melamine resin systems are very complex. Results obtained enable to explain the effect of precursor type on the structure of resulting polymer network, and thus, on the coating properties.</p>
| Identifer | oai:union.ndltd.org:uns.ac.rs/oai:CRISUNS:(BISIS)77634 |
| Date | 22 July 2011 |
| Creators | Jovičić Mirjana |
| Contributors | Radičević Radmila, Stoiljković Dragoslav, Budinski-Simendić Jaroslava, Marinović-Cincović Milena |
| Publisher | Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, University of Novi Sad, Faculty of Technology at Novi Sad |
| Source Sets | University of Novi Sad |
| Language | Serbian |
| Detected Language | English |
| Type | PhD thesis |
| Format | application/pdf |
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