Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: In papermaking, fillers and additives are used to enhance paper properties. In this study spherical modified poly(vinyl alcohol) (PVA) particles were prepared for use as fillers. In order to determine the mechanism of adhesion of additives to cellulose (paper) fibres, these particles were modified to have surface functionality, with cationic and anionic surface charges, similar to charged polyelectrolyte additives. Typically, retention aids used to improve the fibre–fibre and fibre–filler bonding are able to conform to the surface of the fibres and fillers. Oppositely charged components show strong affinity for each other, e.g. cationic polyelectrolyte groups adhere to anionic surface charges on the fibres. The spherical PVA particles were prepared by the saponification of spherical poly(vinyl pivalate) (PVPi) precursor particles. These PVPi particles, prepared via suspension polymerisation, were cross-linked with a divinyl ether comonomer. The vinyl pivalate (VPi) suspension polymerisation was successfully carried out and afforded relatively uniformly distributed PVPi particles, with diameters of 0.5–10 mm. The cross-linked PVPi particles were then saponified in tetrahydrofuran (THF) as swelling solvent, to afford PVA with various degrees of saponification (DS). The spherical shape was lost and fibrous material was obtained when uncross-linked PVPi particles were saponified. Cross-linking the spherical PVPi particles (PVA precursor) proved innovative, and essential in maintaining the spherical form during saponification to PVA/PVPi. By varying the saponification time periods, various DS were obtained, as characterised by solid state NMR spectroscopy. Surface modification of the PVA/PVPi particles was carried out with cationic and anionic groups via the Williamson ether synthesis. Ionic modification of these rigid spherical PVA/PVPi particles was carried out in order to study their adherence to cellulose fibres, compared to the adherence of similarly modified starches with cellulose fibres. Fluorescent labelling of the different modified particles was carried out using two complimentary coloured fluorescent markers. Fluorescence imaging and scanning electron microscopy (SEM) enabled the observation of particle– fibre and particle–particle interaction. Results indicated that the negative groups are sparse on the cellulose fibres, and therefore particles with low functionality but which are able change shape and conform and adhere to the surface of the cellulose fibres are required for effective adhesion. These modified spherical PVA/PVPi particles are unique as they mirror the chemistry of functionalised starch and cellulose particles, yet maintain their shape and have a fixed size, measurable by SEM and transmission electron microscopy (TEM). Field-flow fractionation was also used to characterise and measure these relatively large cross-linked and fixed diameter particles. / AFRIKAANSE OPSOMMING: In papierproduksie word vulstowwe en bymiddels gebruik om die eienskappe van papier te verbeter. In hierdie studie is sferiese poli(vinielalkohol) (PVA) partikels berei vir gebruik as vulstowwe. Om ten einde die meganisme van die bymiddelklewing aan die sellulose vesels (papier) te bepaal, is die oppervlakke van hierdie partikels gewysig met kationiese of anioniese groepe, om 'n oppervlak soortgelyk aan dié van funksionele poliëlektrolietbymiddels te verskaf. Die retensiemiddels wat gebruik word om die vesel–vesel en vesel–vulstof binding te verbeter is tipies in staat om te konformeer aan die oppervlak van die vesels en vulstowwe. Teenoorgesteldgelaaide komponente toon 'n sterk affiniteit vir mekaar, bv. kationiese poliëlektrolietgroepe is vasklewend aan die anioniesgelaaide oppervlakke van die vesel. Die sferiese PVA partikels is berei deur die verseping van sferiese poli(vinielpivalaat) (PVPi) partikels. Hierdie voorloper PVPi partikels, berei deur suspensiepolimerisasie, is gekruisbind met 'n divinieleter ko-monomeer. Die vinielpivalaat (VPi) suspensiepolimerisasie is suksesvol uitgevoer en relatief eenvormig verspreide sferiese PVPi partikels is berei, met deursnitte tussen 0.5–10 mm. Die gekruisbinde PVPi partikels is daarna gesaponifiseer in tetrahidrofuraan (THF) as oplosmiddel, om PVA met verskillende grade van verseping (DS) te berei. Die sferiese vorm raak verlore en veselagtige materiaal is verkry wanneer PVPi partikels met geen kruisbinding verseep is. Kruisbinding van die sferiese PVPi partikels (PVA voorloper) is voordelig en noodsaaklik om die sferiese vorm tydens die verseping tot PVA/PVPi te behou. Deur die tydsduur van verseping te verander, is verskeie grade van verseping verkry en bevestig deur vaste toestand KMR spektroskopie. Oppervlakwysiging van die PVA/PVPi partikels, om kationiese en anioniese groepe aan te heg, is uitgevoer via die Williamson etersintese. Ioniese wysiging van hierdie stram, sferiese PVA/PVPi partikels is uitgevoer om ten einde hul klewing met sellulose vesels te bestudeer en te vergelyk met die klewing van soortgelyk gewysigde stysels. Fluoressensie merking van die verskillende gewysigde partikels is uitgevoer met behulp van twee komplimentêre gekleurde fluoressensie merkers. Fluoressensie beeldvorming en SEM verskaf die waarneming van partikel–vesel en partikel–partikel interaksie. Die resultate dui daarop dat die negatiewe groepe van die sellulose vesels skaars is, en daarom is partikels met ‘n lae funksionaliteit, maar wat in staat is om van vorm te verander, aan te pas en te konformeer aan die oppervlak van die sellulose vesels, nodig vir effektiewe adhesie. Hierdie gewysigde sferiese PVA/PVPi partikels is uniek aangesien hulle die chemie van gewysigde stysel en sellulose partikels naboots, maar steeds hul vorm behou met 'n vaste grootte; meetbaar deur SEM en TEM. Veld-vloei-fraksionering is ook gebruik vir die karakterisering van hierdie relatief groot, stram, gekruisbinde partikels met bepaalde deursneë.

Submitted by Kilvya Braga (kilvyabraga@hotmail.com) on 2018-04-19T14:53:27Z No. of bitstreams: 1 MARIAUGUSTA FERREIRA MOTA - TESE (PPGEQ) 2015.pdf: 7929755 bytes, checksum: 46b508fdcbc2c553fa37592a200d2ae5 (MD5) / Made available in DSpace on 2018-04-19T14:53:27Z (GMT). No. of bitstreams: 1 MARIAUGUSTA FERREIRA MOTA - TESE (PPGEQ) 2015.pdf: 7929755 bytes, checksum: 46b508fdcbc2c553fa37592a200d2ae5 (MD5) Previous issue date: 2015-02-27 / CNPq / Este trabalho de Tese descreve a preparação de argilas organofílicas a partir da argila Brasgel e Verde-Lodo naturais que foram utilizadas como cargas para síntese de nanocompósitos via polimerização in situ em suspensão e polimerização in situ em massa-suspensão. A caracterização para avaliar as argilas organofílicas foi realizada a partir das técnicas de Difração de raios X (DRX), Espectroscopia na Região do Infravermelho por Transformada de Fourier (IV) Análise Térmica Diferencial e Termogravimétrica (ATD/TG) e ensaios de expansão (Capacidade de Adsorção e Inchamento de Foster). A produção de nanocompósitos poli(pivalato de vinila)/argila foi realizada a partir da polimerização in situ em suspensão do pivalato de vinila utilizando 2,5% e 5% de argila Brasgel ou Verde-Lodo modificadas com os sais Praepagen, Dodigen e Genamin. O processo de obtenção do nanocompósito poli(metacrilato de metila)/argila foi realizada a partir da polimerização in situ em massa-suspensão do metacrilato de metila utilizando 3% de argilas Verde-Lodo natural ou modificadas com os sais Praepagen, Dodigen e mistura de sais (Praepagen + Dodigen). Os nanocompósitos polímero/argila foram caracterizados a partir de DRX, IV, TG, Microscopia Óptica (MO), Microscopia Eletrônica de Varredura (MEV) e Calorimetria Diferencial de Varredura (DSC). Os resultados de DRX mostram a intercalação dos sais quaternários de amônio (Praepagen, Dodigen e Genamin) em todas as argilas (Verde-Lodo e Brasgel) no processo de organofilização. Os resultados de IV e ATD indicam que os sais foram incorporados à estrutura da argila, evidenciando assim o processo de organofilização. Os testes de Capacidades de Adsorção comprovaram as melhores eficiências das argilas Verde-Lodo e Brasgel organofilizadas com os sais quaternários de amônio em relação às argilas na sua forma natural independente do solvente orgânico utilizado. Os resultados dos testes de Inchamentos de Foster indicaram que as afinidades dos sais ocorreram nas argilas organofílicas avaliadas em todos os solventes orgânicos. Os resultados obtidos de DRX a partir da polimerização in situ em suspensão do pivalato de vinila/argila Brasgel ou Verde-Lodo organofílicas indicaram interações argila-polímero na forma intercalada e esfoliada. As análises de TG indicaram que ocorreu diminuição no intervalo de 3oC a 10oC da temperatura máxima de degradação assim como a diminuição da Temperatura de transição vítrea (Tg) dos nanocompósitos contendo 2,5 e 5% de argila na matriz polimérica Poli(pivalato- vinila). Para os nanocompósitos sintetizados a partir do metacrilato de metila e da argila Verde-Lodo natural e organofilizadas os resultados de DSC a partir da polimerização in situ em massa-suspensão do metacrilato de metila/argila VerdeLodo natural e organofílicas indicaram que as temperaturas de transição vítrea não foram alteradas com a adição da argila. As análises de TG mostraram que houve alterações pouco significativas na temperatura máxima de degradação e as imagens de MEV indicaram que a morfologia dos nanocompósitos obtidos com 3% de argila Verde-Lodo organofilizadas apresentaram partículas esféricas e lisas, indicando interação da argila com a matriz polimérica. / This Doctorate Thesis describes the preparation of organoclays from raw clays Brasgel and Green-Sludge, which were used as charge materials to synthesis of nanocomposites via in situ suspension and in situ mass-suspension polymerization reactions. The organoclays characterization was carried out by making use of techniques of X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Differential Thermal Analysis and Thermogravimetric Analysis (DTA/TGA), and analysis of adsorption of organic compounds (Adsorption Capacity and Foster’s experiment). The synthesis of nanocomposites poly (vinyl pivalate)/clays were performed from in-situ suspension polymerization reaction of vinyl pivalate with 2.5% w. and 5% w. of organoclays Brasgel or Green-Sludge, in which were organophilized by using the quaternary ammonium salts Praepagen®, Dodigen®, and Genamin®. The synthesis of nanocomposites poly (methyl methacrylate)/clays were realized from in-situ mass-suspension polymerization reaction of methyl methacrylate with 3% w. of raw clay Green-Sludge or organoclay Green-Sludge organophilized by using the quaternary ammonium salts Praepagen®, Dodigen®, and the mixer of these surfactants (Praepagen® + Dodigen®). The nanocomposites polymer/clay were characterized with the techniques XRD, FTIR, TGA, Optical Microscopy (OM), Scanning Electron Microscopy (SEM), and Differential scanning calorimetry (DSC). The characterization results have shown the intercalation of the cations from the quaternary ammonium salts (Praepagen®, Dodigen®, and Genamin®) within the raw clays (Green-Sludge and Brasgel) after the organophilization reaction. The results of FTIR and DTA indicate that the cations of the surfactants were incorporated in the raw clays, in which it is related the organophilization process. The results of adsorption capacity of organic compounds show that the organoclays Green-Sludge and Brasgel compared with its respective raw clay form have higher adsorption of organic compounds for all compounds analyzed. The Foster’s experiment shows that all the organoclays synthetized have high affinity with organic molecules for all compounds analyzed. The results of XRD analysis from in-situ suspension polymerization of vinyl pivalate/Brasgel raw clay or organoclays Green-Sludge have shown the clay-polymer interactions in intercalated and exfoliated forms. From TGA analysis has been observed a decreasing of the maximum temperature of degradation between 3°C and 10°C, as well the decreasing of the glass transition temperature (Tg) for the nanocomposites with 2.5% w. and 5% w. of clay in the polymeric matrix poly (vynil pivalate). By analyzing the nanocomposites synthetized from methyl methacrylate and Green-Sludge raw clay or organoclays, the results of DSC have shown that the glass transition temperature does not change with the presence of clays. The TGA analysis has demonstrated the occurrence of small variations of the maximum temperature of degradation. The SEM results indicate that the morphology of the nanocomposites synthetized from 3% w. of organoclay GreenSludge has smooth and spherical particles, which indicates the interaction between the clay within the polymeric matrix.