Thesis (Ph.D)--Technische Universiteit Eindhoven, 2006. / Title from title screen (viewed on Dec. 6, 2007). Title from document title page. Includes bibliographical references. Available in PDF format via the World Wide Web.

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A Dissertation Submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the Degree of Master of Science in Polymer Chemistry. / The dissertation studies the synthesis, formulation development, crosslinking and spectral characterisation of dehydrated castor oil poly(glyceryl phthalate) alkyd resins for use as air-dry surface coating vehicles. Synthesis of alkyd resins involves simultaneous dehydration, alcoholysis and polyesterification reactions. Dehydration of castor oil is achieved in situ under phthalic anhydride catalysis. Alcoholysis of dehydrated castor oil by glycerol is also achieved in situ to form predominantly the monoglyceride. Polyesterification of the resultant mono- and diglycerides is realised through interaction with phthalic anhydride. The reaction is carried out at 280°C for 3 hours and at 225°C for 2 hours under azeotropic distillation with xylene. The parent poly(glyceryl phthalate) alkyd resin is synthesized by reaction of castor oil, glycerol and phthalic anhydride to a predetermined acid value. Formulation development experiments were carried out to study the effect of variations in the dibasic acid to polyol/oil and polyol to oil ratios on alkyd resin properties. Model formulations exhibiting the best alkyd performance were developed. Predictive model formulation equations were derived from model formulation data and their limits of reliability and applicability established. The formulation of water soluble alkyd resins is modified to introduce pendant carboxylic acid groups along the polymer skeleton. Water solubility is achieved by neutralisation of the residual pendant carboxylic acid groups by 'fugitive' amines to yield water soluble alkyd soaps. The effect of variations in the nature and level of incorporation of amine is investigated. Alkyd resin solubilisation and resin acidity guide formulae were studied and developed. Cross-linking chemistry of alkyd resins, both in the reactor (gelation) and on application (film formation) is investigated. Gelation manifested itself in two different forms, thermoplastic and thermosetting. An important alkyd constant, K, was established as an indispensable tool in control of premature gelation and in the prediction of resin drying characteristics. Autooxidation and solvent evaporation are the two competing curing mechanisms encountered in film formation. The nature and influence of each curing mechanism on the rate of cure and film characteristics is highlighted. Catalysis experiments were conducted with metallic driers (Co2 Mn2 and Pb2} to bring the rate of drying of resin films to economically feasible limits and catalyst addition levels were established. New spectral characterisation techniques based on Fourier Transform Infrared spectroscopy were investigated. An extensive study was carried out on FT IR spectral data to establish qualitative and quantitative relationships between transmission peak ratios and alkyd resin composition. Series dependent and series independent correlation equations, useful in quantifying alkyd resin components were derived. A new FT IR spectroanalytic characterisation method for dibasic acids is proposed. The method, if adopted, affords both qualitative and quantitative characterisation of the dibasic acid component in the alkyd resin matrix and it is envisaged the technique will supersede conventional methods in terms of speed and simplicity.' / Andrew Chakane 2021

<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 sme&scaron;a smola praćeno je FTIR spektroskopijom, dinamičko skanirajućom kalorimetrijom (DSC), reometrijom, kao i određivanjem sadržaja gela. Ispitivana su toplotna svojstva, dinamičkomehaničko pona&scaron;anje, fizičko-mehaničke karakteristike i hemijska otpornost filmova premaza. Umrežavanje sme&scaron;a smola teče uglavnom preko hidroksilnih i karboksilnih grupa alkida sa izobutoksimetil i metoksimetil grupama u melaminskim smolama. Sintetisane klasične alkidne smole u sme&scaron;i sa melaminskim smolama umrežavaju u temperaturnom opsegu od 90 do 170&nbsp;⁰C, a hiperrazgranati alkidi od 80 do 170&nbsp;⁰C, &scaron;to su uobičajene temperature u tehnologiji lakova koji umrežavaju &ldquo;pečenjem&ldquo;. Umreženi filmovi premaza su toplotno veoma stabilni, budući da početak razgradnje premaza započinje na temperaturama od 281 do 330 ⁰C. Potvrđeno je da postoji linearna zavisnost između modula izgubljene energije na 25 ⁰C, koji je mera viskoznog odgovora materijala, i tvrdoće premaza određene metodom klatna. Svi projektovani premazi, bez obzira na nesavr&scaron;enost nastale polimerne mreže, su pokazali zadovoljavajuća svojstva. Najbolja svojstva od klasičnih alkidnih premaza ima onaj na osnovu sme&scaron;e alkida sa etoksilovanim pentaeritritolom i heksametoksimetil melaminske smole. Kori&scaron;ćenje hiperrazgranatih alkidnih smola kao veziva u ekolo&scaron;ki prihvatljivim premazima ima prednost zbog manjeg sadržaja organskih rastvarača i manje viskoznosti u odnosu na klasične smole. Pretpostavljeno je da bi sme&scaron;e 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>