Thesis (PhD)--Stellenbosch University, 2005. / ENGLISH ABSTRACT: Finding use for byproducts from the chemical industry holds many advantages for a country's economy. Synthesis of new monomers from such byproducts adds value to otherwise otherwise low-value material. The synthesis of a new olefin-modified acrylate monomer, 1-methyl-1-propyl-hexyl acrylate (1-MPHA), derived from 1-pentene, is reported. Homopolymerisation of the monomer 1-MPHA was carried out in both benzene and in toluene. The products of full-conversion of the homopolymer poly-(1-MPHA) were characterised by GPC, NMR, TGA and DMA. Kinetic studies of the homopolymerisation process of 1- MPHAwere also undertaken. The monomer 1-methyl-1-propyl-hexyl acrylate (1-MPHA) was copolymerised with methyl methacrylate (MMA). Samples obtained from full conversion copolymerisations at various 1-MPHAIMMAfeed ratios were characterised by GPC, NMR, TGA and DMA. Reactivity ratios of the two monomers were obtained from in situ 1H NMR kinetic studies. 1-MPHA was also copolymerised with vinyl acetate (VAc). Samples obtained from full conversion copolymerisation with a 1-MPHA content ranging from 2 to 16 wt% were characterised by GPC, NMR, TGA and DMA. The solubility parameter and the hydrophobicity of the VAc/1-MPHA copolymers were also determined. Reactivity ratios of the two monomers were obtained from in situ 1HNMR kinetic studies. Further copolymerisation studies with styrene and glycidyl methacrylate as comonomers were undertaken. The chemical analysis and thermogravimetric analysis of the copolymers are reported. In conclusion, the use of 1-methyl-1-propyl-hexyl acrylate as a comonomer results in a reduction in the glass transition temperature, better thermal stability, increased hydrophobicity with an insignificant loss in stiffness of the copolymers. These properties are due to the long and branched chain structure of the 1-MPHA monomer. / AFRIKAANSE OPSOMMING: Gebruik van byprodukte van die chemiese nywerheid hou groot voordele in vir die land se ekonomie. Sintese van nuwe monomere vanuit sulke byprodukte dra by tot waardetoevoeging tot andersins lae-waarde byprodukte. Die sintese van 'n nuwe olefien-gewysigde akrilaatmonomeer afkomstig van 1-penteen, naamlik 1-metiel-1-propiel-heksielakrilaat (1-MPHA), word hier beskryf. Homopolimerisasie van die monomeer 1-MPHA is uitgevoer in beide benseen en tolueen. Die produkte van die volledige omskakeling van die homopolimeer is met behulp van GPC, KMR, TGA en DMA gekarakteriseer. Die reaksiekinetika van die homopolimerisasie van 1-MPHA is ook ondersoek. Die monomeer 1-MPHA is met metielmetakrilaat (MMA) gekopolimeriseer. Monsters van die volledig omgeskakelde kopolimere met verskeie 1- MPHNMMA voerverhoudings is m.b.v. GPC, KMR,' TGA en DMA gekarakteriseer. Die reaktiwiteitsverhoudings van die twee monomere is vanaf 1HKMR-studies bepaat. 1-MPHA is ook met vinielasetaat (VAc) gekopolimeriseer. Monsters van die produk van die volledige kopolimerisasie met 1-MPHA , met 'n inhoud van 2- 16 massa 0/0, is ook m.b.v. GPC, KMR, TGA en DMA gekarakteriseer. Die 1- MPHA het die hidrofobisiteit van VAc/1-MPHA aansienlik verhoog. Die reaktiwiteitsverhoudings van die twee monomere is vanaf in situ 1H KMRstudies bepaal. Verdere kopolimerisasiestudies met stireen en glisidielmetakrilaat as komonomere is onderneem. Chemiese- en termogravimetriese analises van die kopolimere is gedoen en gerapporteer. Ter afsluiting, die gebruik van 1-metiel-1-propiel-heksielakrilaat as komonomeer het 'n verlaging in die glasoorgangstemperatuur, verhoogde termiesestabiliteit, verhoogde hidrofobisiteit, en 'n klein verlies in die stewigheid (Eng. stiffness) van die kopolimeer tot gevolg. Hierdie eienskappe is as gevolg van die lang, vertakte kettingstruktuur van die 1-MPHA monomeer.

Thesis (PhD)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: The objective of this research was to produce discrete, nano-shaped polymeric structures on the same length scale as, or one to one copies of, templates, deformable templates or structure-directing hosts. Polymerisation of hydrophobic organic monomers in high concentration surfactant solutions, leads to the formation of shaped particles (rod-like, plank-like and ribbon-like particles) in the micrometer size range. The origin of these regularly shaped particles was investigated. It is proposed that they were not polymeric in nature, but formed by the crystallisation of the surfactant in the presence of electrolytes and ethanol as solvent. The polymeric particles that were formed were found to be of spherical shape, and no directing of the shape was detected. Mesostructured hosts were then investigated for their possible use as structure-directing agents. A series of polyelectrolyte-surfactant complexes of polydiallylammonium chloride with sodium sulphate surfactants (ranging from C10 to C16) were synthesised and characterised in terms of their thermal, mechanical and structural properties. The complex of polydiallylammonium chloride and sodium dodecyl sulphate was selected as an appropriate self-assembled model system for investigations into the structure-directing properties of these new materials. The polymerisation of hydrophobic organic monomers, such as styrene and the di-functional monomer m-diisopropenylbenzene (m-DIB), within the above mesoscopically structured polyelectrolyte-surfactant complex as host, lead to the formation of unconventionally shaped polymeric particles. The influence of the presence of monomers and guest polymers on the phase morphology of the host was investigated by small angle X-ray analyses (SAXS) and dynamic mechanical analyses (DMA). SAXS analyses showed that these new, stable hosts can hold up to 17 % guest polymer before phase disruption is encountered. These findings were supported by changes in the mechanical properties, as determined by DMA. The transmission electron microscopy (TEM) images of particles obtained after polymerisation showed very clearly that the poly-(m-DIB) did not form a continuous copy of the 3D hexagonal structure of the host, but rather colloidal copies of a part of the host structure that swelled the most. The shapes of the polymer mesostructures were dictated by the morphology of the phase of the structure-directing host, to produce nanosized wires (dimensions 4 by 100 nm), cigar-shaped particles (dimensions 8 by 50 nm) and fibrillar bent shapes (larger than 200 nm), as revealed by TEM. According to literature these are the first shaped, polymer nano-particles produced in a soft, selfassembled, organic templating host. / AFRIKAANSE OPSOMMING: Die doel van hierdie navorsing was om diskrete, nano-gevormde polimeriese partikels van dieselfde lengteskaal as, of direkte een tot een kopië van, 'n templaat, 'n vervormbare of struktuur-rigtende gasheersisteem te produseer. Die polimerisasie van hidrofobiese organiese monomere in seep oplossings van hoë konsentrasie, het gelei tot die produksie van gevormde partikels. Die oorsprong van hierdie partikels is ondersoek. Dit word voorgestel dat die partikels nie polimeries van aard is nie, maar gevorm is deur die kristallisasie van die seep in die teenwoordigheid van elekotroliete en etanol as oplosmiddel. Die polimeriese partikels wat wel geproduseer is, was sferies in vorm, en geen rigtende invloed op die vorm van die partikels is waargeneem nie. Meso-gestruktureerde gasheersisteme is ook ondersoek vir moontlike gebruik as struktuur-rigtende agente. 'n Reeks poliëlektroliet-seep komplekse van polidiallielammoniumchloried en natriumsulfaat sepe (van C10 tot C16) is gesintetiseer en gekarakteriseer in terme van hul termiese, meganiese en strukturele eienskappe. Die kompleks van polidiallielammoniumchloried en natrium dodekielsulfaat is gekies as 'n toepaslike self-organiserende modelsisteem vir die ondersoeke na die struktuur-rigtende eienskappe van hierdie nuwe materiale. Polimerisasie van hidrofobiese organiese monomere, soos byvoorbeeld stireen en die di-funksionele monomeer m-di-isopropenielbenseen (m-DIB), in hierdie mesoskopies-gestruktureerde poliëlektroliet-seep kompleks, het gelei tot die vorming van nie-konvensionele gevormde polimeriese partikels. Die invloed van die teenwoordigheid van monomere en gaspolimere op die fasemorfologie van die gasheersisteem is ondersoek d.m.v. kleinhoek X-straal diffraksie (Eng. SAXS) en dinamiese meganiese analise (DMA). SAXS analises het aangetoon dat hierdie nuwe, stabiele gasheersisteem tot 17 % gaspolimeer kan inkorporeer voordat fasevernietiging plaasvind. Hierdie resultate is verder ondersteun deur veranderinge in die meganiese eienskappe soos waargeneem deur DMA. Transmissie elektronmikroskopie (TEM) afbeeldinge van partikels geïsoleer na polimerisasie het baie duidelik gewys dat, in die geval van poli-(m-DIB), die gaspolimeer nie 'n kontinue kopie van die drie dimensionele heksagonale struktuur van die gasheersisteem produseer nie. Daar word eerder 'kolloïdale kopieë' van dele van die gasheersisteem wat die meeste swel gevorm. Die vorms van die polimeer mesostrukture word dus bepaal deur die morfologie van die fase van die struktuur-rigtende gasheer, om nanogrootte draadjies (dimensies 4 x 100 nm), sigaarvormige partikels (8 x 50 nm) en fibrillêre gebuigde vorms (groter as 200 nm) te vorm, soos waargeneem met TEM. Volgens die literatuur is hierdie die eerste geval van gevormde polimeer nanopartikels geproduseer in 'n self-organiserende templaat gasheersisteem.

Thesis (PhD)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: From the Sasol Fischer- Tropsch process, a variety of different a-olefins are produced. Sasol recently started presenting these a-olefins to polymer producers. To demonstrate the application possibilities of these a-olefins as comonomers for ethylene and propylene polymerization, it was necessary to first synthesize catalysts having a combination of high activity and good comonomer incorporation, and in the case of propylene copolymers, also sufficient stereospecificities. Different methods to produce catalysts conforming to these requirements were investigated and it was found that catalysts produced from a MgCb-support activated by a combination of chemical and mechanical means produced suitable catalysts. The amount of alcohol used during the support activation step and the time allowed for alkylation of the active centers were important. No clear correlation between total titanium content and activity was observed. The degree to which active sites are protected was evaluated from the amount of comonomer present in the final copolymer based on the amount added to the reaction. Cyclopentadiene was used to selectively deactivate the unprotected active sites to determine the ratio between protected and "open" active sites. High activity catalysts are not suitable for gas-phase copolymerization and were consequently "diluted" by dispersion in a pre-formed polymer powder and by prepolymerization. Catalyst activity based on titanium content was substantially decreased, but comonomer incorporation was not. Catalysts for producing crystalline polypropylene require the presence of both an internal and external electron donor. It was shown that isotacticity increased linearly with an increase in external modifier at the expense of catalyst activity and that a double treatment of the support or catalyst before the final TiCl4 fixation was more effective at increasing stereospecificity. The less stereospecific sites are more capable of accepting bulky comonomers in the coordination complex and thus by decreasing the amount of less-stereospecific active sites, the overall capability of the catalyst to incorporate comonomer was decreased. Comonomer sequence distributions and average lamellar thicknesses of different ethylene / a-olefin copolymers were calculated from CH2 dyad concentrations determined by I3C NMR spectroscopy. Ethylene sequences in the I-butene containing copolymers are generally longer than those where a higher a-olefin was used as comonomer which indicates that a more random comonomer distribution is obtained when the higher u-olefins are used. It was shown that an inverse relationship exists between branch size and density. For density, no effect resulting from the comonomer type was observed. This same inverse relationship was also observed for tensile strength. Modulus, hardness and impact strength, on the other hand, did show an effect resulting from the comonomer type. Modulus and hardness were not depressed as much and impact strength improved more than what was expected from calculations based on branch size. Homogeneous copolymers have broad melting peaks. It was shown that at sufficiently high comonomer content, peak broadening occurs when the higher cc-olefins are used as comonomer, which also indicates that more random comonomer distributions are obtained with the higher aolefins. From the chain propagation probabilities calculated it was observed that two types of active sites are present. Those responsible for producing mainly polyethylene have an alternating character while the sites capable of incorporating comonomer have a blocky character. It was expected that the additional introduction of a third a-olefin during ethylene / 1- pentene copolymerization will produce a terpolymer with density and related properties similar to the mathematical average between those of the relevant copolymers. This was only observed for the terpolymers containing l-heptene, 1- octene and l-nonene. The I-butene containing terpolymers have densities well below the expected values while the I-hexene containing terpolymers have values very similar to that of the ethylene / l-hexene copolymer densities, but still below the expected values. Properties related to density, such as tensile strength and modulus, follow this same trend. It is believed that the presence of l-pentene breaks up the tendency of the lower c-olefins to cluster which results in improved randomness. Compared to the copolymers, I-butene and l-hexene containing terpolymers seem to reach the impact strength maximum at a lower total comonomer content than that of the I-pentene copolymers which also indicates an enhanced effect from the combined use of I-pentene with these o-olefins. No substantial difference between impact strengths of co- and terpolymers prepared with higher a-olefins was observed. In general, the melting temperatures of the terpolymers are slightly lower and spread over a wider temperature range than those of the copolymers which can be realized if the comonomer units are less clustered and thus more randomly distributed. Decrease in melting temperature was, however, not as much as for the metallocene catalyzed terpolymers. From sequence length calculations from l3C NMR spectroscopy it was found that the crystallizable ethylene sequences of l-butene containing terpolymers were shorter than those of the corresponding copolymers, which confirms the notion that the introduction of a third comonomer resulted in an increase in randomness. Crystallizable sequence lengths became gradually shorter when higher cc-olefins were used in co- and terpolymers and those of the terpolymers are generally shorter. From the different types of active centers present on a Ziegler-Natta catalyst, it was reasoned that three main types of polymer chains can be present in the terpolymers: (a) ethylene homopolymer, (b) ethylene / lower a-olefin copolymer and (c) ethylene / lower a-olefin / higher a-olefin terpolymer. The ratio between these components in the final terpolymer depends primarily on the size of the higher a-olefin. The larger the third a-olefin becomes, the more active sites will reject it, resulting in a higher amount of ethylene / lower a-olefin copolymer. It was thus suggested that the large decrease in density and the associated change in related properties observed for ethylene / l-pentene / l-butene terpolymers can be related to the combined result of improved random comonomer incorporation together with the decrease in the amount of ethylene homopolymer. The possibilities of using the higher a-olefins having uneven carbon numbers were investigated in random propylene copolymers. Similar to that observed for the ethylene copolymers, less of the higher a-olefins was necessary to achieve a certain level of crystallinity. A good agreement was observed between tensile properties and comonomer type and content and the size of the branch and the resulting defect it causes in the crystal structure is the primary factor affecting tensile strength. For impact strength a close correlation between the size of the comonomer side chain and comonomer content was observed. It was shown that the effect of the heptyl branch derived from a l-nonene unit was 2.3 times that of the propyl group derived from the I-pentene unit. Properties of block copolymers can not be related directly to l-pentene content as is the case with random copolymers, mainly due to the heterogeneity of the block copolymers. The activating effect of hydrogen on catalyst activity was observed. It was also observed that the amount of l-pentene incorporated in the copolymer as well as the copolymer yield were higher in the presence of hydrogen than when the reaction was carried out in the absence of hydrogen. By using DSC it was possible to identify different crystalline phases in the propylene / I-pentene block copolymers due to the differences in their crystallization kinetics. A connection between the low-temperature peak and impact strength was observed. It was found that the presence of the low-temperature peak resulting from thin lamellae formed by chain containing many defects was undesirable when high impact strength is required. It was not possible to quantify the extent to which the intensity of this peak affected mechanical properties of the block copolymers. However, from sequence length calculations it was found that the ratio between the propylene and 1- pentene sequence lengths could be related quantitatively to impact strength, modulus, hardness and tensile strength of the polymers investigated. / AFRIKAANSE OPSOMMING: 'n Verskeidenheid van verskillende «-olefiene word in die Sasol Fischer- Tropsch proses vervaardig. Sasol het onlangs begin om hierdie a-olefiene aan polimeervervaardigers te bied. Om die toepassingsmoontlikhede van hierdie aolefiene as komonomere vir etileen en propileen polimerisasie te demonstreer was dit nodig om eerstens 'n katalis met 'n kombinasie van hoë aktiwiteit en goeie komonomeer invoeging te sintetiseer. In die geval van propileen word voldoende stereospesifisiteit ook vereis. Verskillende metodes om kataliste wat aan hierdie vereistes voldoen te vervaardig is ondersoek. Daar is gevind dat kataliste waarvan die MgCb basis deur 'n kombinasie van chemiese- en meganiese metodes geaktiveer is, die vereiste eienskappe besit. Die hoeveelheid alkohol gebruik tydens die basis aktivering stap en die tyd toegelaat vir die alkilering van die aktiewe spesies was belangrik. Geen duidelike verband tussen totale titaan inhoud en aktiwiteit is waargeneem nie. Die mate waartoe aktiewe spesies beskerm is, is bepaal vanaf die hoeveelheid komonomeer teenwoordig in die finale kopolimeer in verhouding met die hoeveelheid bygevoeg tydens die reaksie. Siklopentadieen is gebruik om onbeskermde aktiewe spesies selektief te deaktiveer om die verhouding tussen beskermde en oop aktiewe spesies te bepaal. Hoëaktiwiteit kataliste is nie geskik vir gasfase kopolimerisasie nie en is gevolglik verdun deur dit te versprei in 'n voorafgevormde polimeer poeier en deur prepolimerisasie. Katalis aktiwiteit gebaseer op titaan inhoud was aansienlik laer maar komonomeer invoeging was nie merkbaar beinvloed nie. Kataliste VIr die vervaardiging van kristallyne polipropileen vereis die teenwoordigheid van beide interne- en eksterne elektron donors. Daar is gewys dat isotaktisiteit liniêr verhoog met 'n toename in eksterne modifiseerder ten koste van katalis aktiwiteit en dat 'n dubbele behandeling van die basis of katalis, voor die finale titaan fiksering, meer effektief was om stereospesifisiteit te verhoog. Die spesies met laer stereospesifisiteit is meer bevoeg om bonkige komonomere in die koërdinasie kompleks toe te laat en deur dus die konsentrasie van hierdie spesies te verlaag is die bevoegdheid van die katalis om bonkige komonomeer te inkorporeer, verlaag. Komonomeer reeksverspreiding en gemiddelde lamellêre dikte van verskillende etileen / o-olefien kopolimere is bereken vanaf CH2 diad konsentrasie bepaal deur KMR spektroskopie. Etileen reekse in die kopolimere wat l-buteen bevat is oor die algemeen langer as dié waarin 'n hoër a-olefien as komonomeer gebruik was, wat aandui dat 'n meer egalige komonomeer verspreiding verkry word as hoër «-olefiene gebruik word. Daar is getoon dat 'n inverse verhouding tussen die grootte van die vertakking en digtheid bestaan. Geen effek komende van die komonomeer tipe kon waargeneem word nie. Hierdie soortgelyke inverse verhouding was ook waargeneem vir treksterkte. Modulus, hardheid en impaksterkte aan die ander kant, hét 'n effek komende van die komonomeer tipe getoon. Modulus en hardheid was nie soveel verlaag, en impak sterkte soveel verhoog as wat verwag is vanaf berekeninge gebaseer op vertakking grootte nie. Homogene kopolimere toon breë smeltpieke. Daar is gewys dat by voldoende komonomeer inhoud 'n verbreding van die pieke voorgekom het wanneer hoër a-olefiene as komonomere gebruik is, wat ook aandui dat 'n meer egalige komonomeer verspreiding met hierdie c-olefiene verkry kan word. Vanaf berekening van die ketting voortplantingsmoontlikhede is waargeneem dat twee tipes aktiewe spesies teenwoordig is. Die verantwoordelik vir die vorming van polietileen het 'n alternerende karakter terwyl die sentra wat komonomeer kan inkorporeer 'n blokagtige karakter het. Daar is verwag dat die addisionele byvoeging van 'n derde o.-olefien tydens etileen / I-penteen kopolimerisasie, 'n terpolimeer met digtheid en verwante eienskappe soortgelyk aan die wiskundige gemiddelde tussen dié van die relevante kopolimere tot gevolg sal hê. Dit was egter slegs waargeneem vir terpolimere wat I-hepteen 1- okteen en l-noneen bevat. Die I-buteen bevattende terpolimere het digthede ver onder die verwagte waardes terwyl die I-hekseen bevattende terpolimere waardes soortgelyk aan die etileen / l-hekseen kopolimeer digthede het' wat steeds onder die verwagte waardes is. Eienskappe verwant aan digtheid, soos treksterkte en modulus, volg dieselfde neiging. Dit word geglo dat die teenwoordigheid van l-penteen die neiging van die laer a-olefiene om saam te bondelopbreek wat 'n verbeterde egaligheid in komonomeerverspreiding tot gevolg het. Vergeleke by die kopolimere blyk dit dat die terpolimere wat l-buteen en I-hekseen bevat, die impaksterkte maksimum by 'n laer totale komonomer inhoud bereik as dié van die 1-penteen polimere. Dit dui ook op 'n verbeterde effek as gevolg van die gekombineerde gebruik van l-penteen met ander a-olefiene. Geen duidelike verskil tussen die impaksterktes van ko- en terpolimere, wat met die hoër a-olefiene berei was, is waargeneem me. In die algemeen is die smeltingstemperature van die terpolimere effens laer, en versprei oor 'n wyer temperatuurgebied as dié van die kopolimere wat verklaar kan word as komonomere minder saamgebondel is en dus meer homogeen versprei is. Die afname in smelt temperatuur was egter nie soveel as dié van die metalloseengekataliseerde terpolimere nie. Vanaf reekslengte berekeninge met behulp van KMR spektroskopie is daar gevind dat die kristalliseerbare etileen reekse van die l-buteen bevattende terpolimere korter was as dié van die ooreenkomstige kopolimere, wat die gevoel dat die byvoeging van 'n derde komonomeer 'n verbeterde komonomeerverspreiding tot gevolg het, bevestig. Vanaf die verskillende aktiewe spesies teenwoordig in 'n Ziegler-Natta katalis is daar geredeneer dat drie hooftipes polimeerkettings in die terpolimere teenwoordig kan wees: (a) etileen hompolimeer, (b) etileen / laer a-olefien kopolimeer en (c) etileen / laer a-olefien / hoër a-olefien terpolimeer. Die verhouding tussen hierdie komponente in die finale terpolimeer hang primêr van die grootte van die hoër aolefien af. Hoe groter die derde a-olefien is, deur hoe meer van die aktiewe spesies sal dit verwerp word wat 'n groter hoeveelheid etileen / laer a-olefien kopolimeer tot gevolg sal hê. Daar word dus voorgestel dat die groot afname in digtheid en die geassosieerde veranderings in die toepaslike eiensappe waargeneem vir etileen / 1- penteen / I-buteen terpolimeere, herlei kan word na die gekombineerde effek van verbeterde komonomeerverspreiding tesame met die afname lil die hoeveelheid etileen homopolimeer. Die moontlikheid om hoër cc-olefiene met onewe koolstofgetalle te gebruik in homogene propileen kopolimere is ondersoek. Soortgelyk aan dit wat waargeneem is vir die etileen kopolimere, was minder van die hoër cc-olefiene nodig om 'n spesifieke vlak van kristalliniteit te bereik. 'n Goeie ooreenkoms tussen trek-eienskappe en . komonomeer tipe- en inhoud is waargeneem en die grootte van die vertakking en die gevolglike defek wat dit veroorsaak in die kristal struktuur is die primêre faktor wat treksterkte beinvloed. Vir impaksterkte is 'n noue verband tusssen die grootte van die vertakking en komonomeer inhoud waargeneem. Daar is aangetoon dat die effek van die heptiel vertakking vanf die l-noneen eenheid 2.3 keer dié van die propiel groep van die l-penteen eenheid is. Eienskappe van blok kopolimere kan nie direk na l-penteen inhoud herlei word soos die geval met die homogene kopolimere was nie, hoofsaaklik as gevolg van die heterogeniteit van die blok kopolimere. Die aktiverende effek van waterstof op katalis aktiwiteit is waargeneem. Daar is ook gesien dat die hoeveelheid l-penteen geïnkorporeer in die kopolimeer, sowel as die kopolimeer opbrengs, hoër was in die teenwoordigheid van waterstof as wanneer die reaksie sonder waterstof uitgevoer is. Deur DSC te gebruik was dit moontlik om verskillende kristallyne fases in die propileen / l-penteen blok kopolimere vanaf die verskille in hulle krisallisasie kinetika, te identifiseer. 'n Verbintenis tussen die lae-temperatuur piek en impaksterkte is waargeneem. Daar is gevind dat die teenwoordigheid van die laetemperatuur piek, komende van die dun lamellas gevorm, deur kettings wat baie defekte bevat, ongewens is wanneer hoë impaksterkte vereis word. Dit was nie moontlik om die bereik waartoe die intensiteit van hierdie piek die meganiese eienskappe van die blok kopolimere affekteer, te kwantifiseer nie. Vanaf reekslengte bepalings is daar gevind dat die verhouding tussen die propileen en I-penteen reekslengtes kwantitiatief herlei kan word na impaksterkte, modulus, hardheid en treksterkte van die ondersoekte polimere.

Thesis (PhD)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: This study concerns the incorporation of adamantane containing monomers 3-(1-adamantyl)-1-propene and 1-(1-adamantyl)-4-vinylbenzene into ethene, propene and higher a-olefins using different catalytic systems. The effect of the incorporation of the adamantane monomer on the physical and thermal properties of the polymers was investigated. A thorough study on the background of adamantane in general, as well as polymerization reactions involving the above-mentioned monomers and a-olefins was done. 3-(1-Adamantyl)-1-propene as well as 1,.(1-adamantyl)-4-vinylbenzene was sucessfully synthesized. The homo polymers of each monomer were made. The above-mentioned monomers were also polymerized: • . 3-( 1-adamantyl)-1-propene with ethene, propene and higher a-olefins, • 1-(1-adamantyl)-4-vinylbenzene with ethene and styrene. The copolymers of 3-(1-adamantyl)-propene as well as 1-(1-adamantyl)- 4-vinylbenzene were characterized as far as possible to show the influence of the incorporation of the adamantane group on the physical and chemical properties of the polymers. A series of 3-phenyl-1-propene copolymers with higher a-olefins were synthesized to compare the influence of the phenyl group to the adamantyl group on the relevant properties of the polymers. / AFRIKAANSE OPSOMMING: Hierdie studie behels die inkorporasie van adamantaan-bevattende monomere, 3-( 1-adamantiel)-1-propeen en 1-(1-adamantiel)-4-vinielbenseen in eteen, propeen en hoër a-olefiene met behulp van verskillende katalitiese sisteme. Die effek wat die inkorporasie van die adamantaan monomeer op die fisiese en chemiese eienskappe van die polimere het, is ondersoek. 'n Deeglike studie van die agtergrond van adamantaan in die geheel, sowel as die polimerisasie reaksies van die bogenoemde monomere met a-olefiene, is gedoen. 3-( 1-Adamantiel)-1-propeen sowel as 1-(1-adamantiel)-4-vinielbenseen is suksesvol berei. Die homopolimere van bogenoemde monomere is gesintetiseer. Bogenoemde monomere is gepolimeriseer: • 3-(1-adamantiel)-1-propeen met eteen, propeen en hoër a-olefiene, • 1-(1-adamantiel)-4-vinielbenseen met eteen en stireen. Die kopolimere van 3-(1-adamantiel)-1-propeen en 1-(1-adamantiel)- 4-vinielbenseen is sover moontlik gekarakteriseer om die invloed van die adamantaan groep op die fisiese en chemiese eienskappe van die polimeer te toon. 'n Reeks kopolimere van 3-(1-feniel)-1-propeen met hoër a-olefiene is gesintetiseer om die verwantskap tussen die invloed van die fenielgroep en die adamantielgroep op die relevante eienskappe van die polimere te toon.

Thesis (PhD)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: The study focused on the analysis of a variety o f synthesised tailored copolymers. During the investigation o f the samples new and innovative analytical techniques were developed to be able to identify the presence of certain predicted or expected copolymerisation products. Emphasis was placed on the versatility of CRYSTAF as a method for the analysis of semi-crystalline copolymers. Changes in the crystallisation temperature were used as an indicator, while the type o f method, solvent and sample weight served as variables in the system. The percentage comonomer content distribution for an unknown sample was determined from the standard curve plotted with the aid o f copolymers with known comonomer content. Ethylene/higher a-olefin and propylene/higher a-olefm copolymers were synthesised by means o f a metallocene precatalyst. In both cases, NMR spectroscopy, DSC, GPC, and CRYSTAF were used as analytical tools. In the ethylene series it was shown that the sample mixture was homogenous in the molar mass axis (GPC) but not in the chemical composition axis (CRYSTAF) regarding the comonomer content. For the propylene series, an increase in stereoerrors was observed by NMR and this was correlated with crystallisation on heating a DSC for the range o f copolymers. In the case where ethylene/methyl methacrylate block copolymers were synthesised using metallocene precatalyst, novel detection and separation methods were used and developed. This included the use o f CRYSTAF fitted with a carbonyl filter, high temperature gradient HPLC and high temperature liquid chromatography under critical conditions (LCCC). The last two techniques were the first where separation could be achieved with samples only dissolving at high temperature. All previous mentioned techniques, as well as the coupling of FTIR to GPC and high temperature gradient HPLC via LC-Transform revealed that the samples consisted o f varying ethylene and MMA block lengths. / AFRIKAANSE OPSOMMING: Die doelstelling van die navorsing was die analise van spesiaalvervaardigde kopolimere. Nuwe analitiese tegnieke is vir die bevestiging van sekere voorgestelde kopolimerisasie-produkte ontwikkel. Klem is gelê op die veelsydigheid van CRYSTAF as ’n metode vir die analise van gedeeltelik-kristallyne kopolimere. Veranderinge in die kristallisasie-temperature is as respons gebruik, terwyl die metode van sintese, die oplosmiddel en die hoeveelheid monster as veranderlikes in die sisteem beskou is. ‘n Standaardkurwe vir komonomeerinhoud is opgestel met behulp van kopolimere met ‘n bekende komonomeerinhoud. Hierdie kurwe is gebruik om die komonomeerinhoudsverspreiding van onbekende monsters te bepaal. Etileen/hoër a-olefien- en propileen/hoër a-olefien-kopolimere is met behulp van ‘n metalloseen pre-katalis gesintetiseer. In beide gevalle is KMR spektroskopie, DSC, GPC en CRYSTAF gebruik om die analises uit te uitvoer. Met verwysing na komonomeerinhoud is daar in die geval van die etileenreeks bevind dat die monstermengsel homogeen is met betrekking tot die molere massa, maar nie met betrekking tot die chemiese samestelling nie. Vir die propileenreeks is ’n verhoging in die stereofoute met behulp van KMR waargeneem. Dit is gekorrelleer met kristallisasie weens verhitting tydens DSC-bepalings vir die reeks kopolimere. In die geval van die sinteses van etileen/metielmetakrilaat-blokkopolimere met metalloseen as pre-katalis, moes nuwe waamemings- en skeidingstegnieke ontwikkel word. Dit het die gebruik van CRYSTAF met ’n karbonielfilter, hoetemperatuurgradient- HPLC en hoë-temperatuurvloeistofchromatografie onder kritiese toestande ingesluit. Laasgenoemde twee tegnieke het vir die eerste keer skeiding van monsters wat net by hoe temperature oplos, moontlik gemaak. Bogenoemde tegnieke, sowel as die koppeling van FTIR met GPC en hoë-temperatuur-gradient-HPLC via LC-transformasie het getoon dat die monsters etileen- en MMA-blokke met verskillende lengtes bevat het.

Dissertation (Ph.D.)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: The deposition of platinum catalyst on cation-exchange membranes was achieved by a counter diffusion deposition method known as the Takenaka- Torikai method. The morphology of the platinum catalyst on the membranes were controlled by varying the conditions of the platinum deposition process, such as, temperature, type of reducing agent and concentration of the platinic acid solution. The effect of the sonication of platinic acid solution and the pre-treatment of membranes on the morphology of a platinum catalyst was also investigated. Platinum loading on cation-exchange membranes was determined by UV spectrophotometric and gravimetric analyses. Suitable conditions for the quantitative determination of the platinum loading on membranes by UV spectrophotometric analysis was established through the development of a protocol. Membranes were characterised using different techniques such as, Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), Infrared spectrometry (IR), Dielectric analysis (DEA) and Brunauer Emmett Teller adsorption (BET). The roughness profile of a platinum catalyst embedded on a membrane was explored by various statistical methods. The statistical analysis of various data sets for a surface of a platinum-containing membrane was investigated using the Hurst exponent. The effect of surface modification of membranes on the deposition process, as well as the morphology of the platinum catalyst, was investigated. Membranes were modified with ethylene diamine (EDA) and cetyltrimethylammonium bromide surfactant. Modification of membranes with cetyltrimethylammonium bromide surfactant resulted in a unique textured platinum catalyst. The electrochemical "switching" phenomenon was investigated for EDAmodified membranes and EDA-modified membranes embedded with platinum catalyst. The "switching" phenomenon was observed in i-V cyclic curves, which were obtained by galvanodynamie measurements. The application of electro catalytic membrane systems in the anodic oxidation of water was investigated by electrochemical techniques such as galvanostatic and cyclic voltammetric measurements. / AFRIKAANSE OPSOMMING: Die deponering van 'n platinum katalis op katioon-uitruil membrane is suksesvol gedoen d.m.v. die Takenaka-Torikai metode. Die morfologie van die platinum katalis op die membrane is gekontrolleer deur variasie van die kondisies van die platinum deponeringsproses, bv. temperatuur, tipe reduseermiddel gebruik en konsentrasie van die platiensuuroplossing, asook die ultrasonifikasie van die platiensuuroplossing en voorafbehandeling van die membrane. UV spektrofotometriese asook gravimetriese analitiese metodes is gebruik om die platinumlading op katioon-uitruil membrane te bepaal. Geskikte kondisies vir die kwantitatiewe bepaling van die platinumlading op membrane d.m.v. UV spektrofotometriese analise is ontwikkel deur die skep van 'n protokol. Membrane is gekarakteriseer d.m.v. die volgende tegnieke: Atoomkrag Mikroskopie, Skanderingselektron Mikroskopie, Infrarooi Spektrometrie, di-elektriese analise en Brunauer Emmett Teller adsorpsie. Die skurtheidsprofiel van 'n platinum katalis op 'n membraan is ondersoek deur gebruik te maak van verskeie statistiese metodes. Statistiese analises van verskeie data stelsels van 'n platinum-bevattende membraan is ondersoek deur gebruik te maak van die Hurst eksponent. \ Die effek van oppervlakmodifikasie op membrane sowel as die deponeringsproses en morfologie van die platinum katalis is ondersoek deur die modifikasie van membrane met etileen diamien (EDA) en setieltrimetielammonium bromied as versepingsmiddel Die elektrochemiese omswaai van EDA-gemodifiseerde membrane sowel as gemodifiseerde platinum bevattende membrane is ondersoek d.m.v. galvanodinamiese metings. Die gebruik van elektro-katalitiese membraansisteme in die anodiese oksidasie van water is ondersoek deur gebruik te maak van elektrochemiese tegnieke, bv. galvanostatiese en sikliese voltammetriese metings.

Thesis (PhD)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: Most polypropylene copolymers commercially available have ethylene, and to a lesser degree t-butene as comonomers. Commercially available higher a-olefins, mostly even-numbered, are seldom used for the production of pp copolymers, probably due to cost. Sasol's Fischer- Tropsch oil-from-coal process produces many linear and branched a-olefins as by-products that can be isolated and purified by a relatively cheap refinery process, including the odd-numbered 1- pentene olefin. Sasol's gas-phase Novolen pp plant at Secunda, South Africa is ideally suited to the manufacture of high quality pp random copolymers. As such an opportunity was identified to research the use of higher a-olefins, and more specifically 1-pentene, in the gas-phase production of pp random copolymers. Different methods to produce propylene / 1-pentene random copolymers in the slurry phase on bench-scale were investigated. A procedure was subsequently developed to produce propylene / 1-pentene random copolymers in the gas-phase in 10 litre autoclaves. It was found that commercially available fourth generation supported catalysts successfully incorporated the bulky 1-pentene monomer into the propylene backbone, both during slurry and gas-phase polymerisations. Software modelling was employed to determine the dew points of selected gas mixtures typically found during the production of pp random copolymers. The results indicated that typical process conditions could be employed during the gas-phase polymerisation of propylene and 1-pentene without the risk of condensation taking place inside the reactor. Propylene / 1-pentene random copolymers were subsequently successfully produced on the 800 litre BASF pilot plant in Germany followed by the first commercial production of the copolymer on Sasol's 50m3 Novolen gas-phase plant at Secunda. Using commercially available software the impact of introducing 1-pentene as comonomer during the production of random copolymers on the condenser cooling capacity was evaluated. Feasible and safe plant operating conditions were established for the production of propylene / 1-pentene random copolymers. The relationship between operating pressure and powder morphology was investigated to optimise process conditions. Operating at higher pressure in the gas-phase increases the monomer concentration in the reactor and as such improves the space/time/yield ratio of the 50m3 reactors. It was shown that higher operating pressures could be employed through the introduction of 1-pentene as comonomer during the production of PP random copolymer. The dramatic increase in catalyst productivity observed during the 800 litre pilot plant trials, up to a comonomer ratio of about 5%, supported the results obtained from a kinetic study carried out in bench-scale autoclaves. A comprehensive study was undertaken to compare the rheological, thermal, crystallisation, physical and mechanical properties of propylene / 1-pentene random copolymers with those of commercially available pp random copolymers. A series of propylene homo- and random copolymers with 1-pentene and ethylene as comonomers respectively, was prepared. NMR and IR techniques were developed to facilitate the determination of copolymer composition for the new family of 1-pentene random copolymers. The effect of comonomer content, molecular weight and temperature on the properties of the series of polymers was investigated. The propylene / 1-pentene random copolymers show unique rheological behaviour associated with the short propyl branches in the polymer backbone with minimum zero shear viscosity at about 2% 1-pentene content. The effect of molecular structure changes with comonomer content were analysed by the calculation of square average end-toend distance, packing length, tube diameter, molecular mass between entanglements and critical molecular mass. The viscosity of the 1-pentene random copolymers shows higher shear and temperature sensitivity compared to propylene homo- and ethylene random copolymers. The thermodynamic melting point of the propylene / 1-pentene random copolymers showed a significant decrease with increasing comonomer content in the 0 to 5% range. A wider melting range and higher peak melting point depression rate was observed compared to ethylene random copolymers at similar and increasing comonomer content measured on a weight % basis. It was found that the crystal structure of the propylene / 1-pentene random copolymers contains both the Q- and the y-modifications with the ratio of the respective crystal forms a function of both comonomer content and crystallisation temperature. The glass temperature decreased slightly with increasing comonomer (1-pentene) content. It is proposed that the short branch (propyl) "defects" in the polymer backbone are .incorporated into the crystal lattice resulting in increased rate of melting point depression with increasing (wt%) comonomer content compared to other random copolymers while maintaining relative high stiffness. The propylene / 1-pentene random copolymers exhibit the lowest haze values compared to all commercially available pp random copolymers at corresponding levels of comonomer content on a wt% basis. The stiffness to haze ratio of propylene / 1-pentene random copolymers are unique for all the members of the pp family. An inverse relationship between comonomer content and the measured tensile yield strength and modulus is observed. Application studies conducted on the propylene / 1-pentene random copolymers highlighted several interesting characteristics. Films produced from these copolymers exhibited very low haze and xylene soluble values while maintaining mechanical integrity. In the BOPP application the combination of processability and premium film properties presents a unique opportunity for the family of propylene / 1-pentene random copolymers. Blow moulding and injection moulding trials highlighted several advantages of product properties manufactured with propylene / 1-pentene random copolymers if compared to other commercially available random copolymers. The 1-pentene randoms presented lower in-mould as well as total shrinkage than ethylene based random copolymers. Stabilisation and nucleation studies conducted on the propylene / 1-pentene random copolymers showed that a typical combination antioxidant package and nucleating agent, at normal loading levels, could be used. In the larger pp random copolymer family 1-pentene imparts a better balance of properties than other comonomers. The combination of low melting point and xylene solubles with high stiffness and clarity is unique to propylene / 1-pentene random copolymers. / AFRIKAANSE OPSOMMING: Die oorgrote meerderheid van kommersieel beskikbare polipropileen (PP) kopolimere het etileen, en tot 'n mindere mate buteen, as komonomeer. Die relatief hoë koste van kommersieel beskikbare hoër alfa-olefiene is moontlik die rede waarom hulle selde gebruik word vir die vervaardiging van PP kopolimere. Die Sasol Fischer-Tropsch proses, waartydens olie uit steenkool vervaardig word, lewer verskeie liniêre en vertakte alfa-olefiene as neweprodukte wat geïsoleer en gesuiwer kan word in 'n relatiewe goedkoop rafineringsproses. Dit sluit ook die onewe-koolstofgetal 1-penteen-olefien in. Sasol se gasfase Novolen PP aanleg in Secunda, Suid-Afrika, is besonder geskik vir die vervaardiging van hoë standaard PP statistiese kopolimere. Voortvloeiend hieruit is die geleentheid geidentifiseer om die gebruik van hoër alfa-olefiene, en meer spesifiek 1-penteen, na te vors tydens die gasfaseproduksie van PP statistiese kopolimere. Verskeie metodes om propeleen / 1-penteen statistiese kopolimere in 'n koolwaterstofoplosmiddel op laboratoriumskaal te produseer, is ondersoek. 'n Prosedure is daarna ontwikkel om propileen / 1-penteen statistiese kopolimere ook in die gasfase te vervaardig in 10-liter drukvate. Die bevinding was dat kommersieel beskikbare vierde-generasie ondersteunde kataliste die swaarder 1-penteenmonomeer suksesvol geïnkorporeer het in die propileenketting tydens beide die koolwaterstof oplosmiddel- en gasfase polimerisasiereaksies. Rekenaargebaseerde modellering is gebruik om die kondensasiekondisies van tipiese gasmengsels, teenwoordig tydens die produksie van PP statistiese kopolimere, te bepaal. Die resultate het aangedui dat normale proseskondisies tydens die gasfasepolimerisasie van propileen en 1-penteengeen risiko van kondensasie in die reaktor inhou nie. Propileen / 1-penteen statistiese kopolimere is gevolglik met groot sukses vervaardig by die 800-liter BASF loodsaanleg in Duitsland, gevolg deur die eerste kommersiële vervaardiging van die kopolimeer op die Sasol50m3 Novolen gasfase-aanleg in Secunda. Deur gebruik te maak van kommersieel beskikbare sagteware, is die impak van 1-penteen as komonomeer tydens die vervaardiging van statistiese kopolimere op die verkoelingskapasiteit van die kondensator bepaal. Veilige en uitvoerbare aanlegkondisies is uitgestip vir die vervaardiging van propileen /1-penteen statistiese kopolimere. Die verhouding tussen die reaktordruk en poeiermorfologie is ondersoek om die prosestoestande te optimiseer. Vervaardiging van kopolimere in die gasfase by hoër drukke lei tot verhoogde monomeerkonsentrasie in die reaktor en gevolglik hoër produksiedeursette. Daar is bewys dat tydens die produksie van PP statistiese kopolimere, met 1-penteen as komonomeer, hoër reaktordruk ingespan kan word. Die dramatiese toename in katalisproduktiwiteit waargeneem tydens die 800- liter loodsaanleg proefloop, tot en met 'n komonomeer inhoud van ongeveer 5%, word ondersteun deur die resultate van 'n kinetiese studie uitgevoer in laboriumskaal drukvate. 'n Omvattende studie, om die reologiese, termiese, kristallyne, fisiese en meganiese eienskappe van propileen / 1-penteen statistiese kopolimere te vergelyk met kommersieel beskikbare PP statistiese kopolimere, is uitgevoer. 'n Reeks propileen homo- en statistiese kopolimere, met 1-penteen en etileen as komonomere onderskeidelik, is berei. KMR- en IR- tegnieke is ontwikkel om die bepaling van komonomeersamestelling vir die nuwe familie van 1- penteen statistiese kopolimere te fasiliteer. Die invloed van komonomeersamestelling, molekulere gewig en temperatuur op die eienskappe van die reeks polimere is ondersoek. Die propoleen / 1- penteen statistiese kopolimere toon unieke reologiese eienskappe wat geassosieer kan word met die propielsykettings in die polimeerruggraat. Die viskositeit van die propileen / 1-penteen statistiese kopolimere toon 'n hoër wrywings- en temperatuursensitiwiteit in vergelyking met propileen homo- en etileen statistiese kopolimere. 'n Drastiese verlaging in die termodinamiese smeltpunt van die propileen / 1- penteen statistiese kopolimere met 'n toename in komonomeerinhoud is waargeneem tot en met 'n 5% komonomeerinhoud. Die propileen / 1-penteen statistiese kopolimere toon 'n breër smeltgebied en 'n hoër tempo in die piek smeltpuntafname in vergelyking met etileen statistiese kopolimere met soortgelyke komonomeer inhoud, gemeet op 'n massabasis. Daar is bewys dat die kristalstruktuur van die propileen / 1-penteen statistiese kopolimere beide die alfa en gamma modifikasies bevat. Die verhouding van die onderskeie kristalvorms is 'n funksie van komonomeerinhoud en kristalisasietemperatuur. 'n Afname in die glastemperatuur met verhoogde komonomeer inhoud is waargeneem. Die aanname dat die kort propielsykettings in die polimeerruggraat in die kristalstruktuur geïnkorporeer word, is gemaak. Dit verklaar die hoë afname in die tempo van die smeltpunt met toenemende komonomeer inhoud relatief tot ander statistiese kopolimere, met die handhawing van hoë moduluswaardes. Die besondere deursigtigheid van die propileen / 1-penteen statistiese kopolimere tesame met relatief hoë modulus waardes is uniek. 'n Omgekeerde verhouding tussen komonomeer inhoud en treksterkte asook moduluswaardes is waargeneem. 'n Toepassingstudie uitgevoer met die propileen / 1-penteen statistiese kopolimere het verskeie interessante resultate gelewer. Films vervaardig van hierdie kopolimere toon besonderse deursigtigheid en lae waarde van xileenoplosbaarheid, terwyl meganiese integriteit gehandhaaf word. Voordele in die vervaardigingsproses van BOPP-films asook bogemiddelde filmeienskappe hou unieke moontlikhede vir propileen / 1-penteen statistiese kopolimere in. Verskeie voordele tydens blaas- en spuitvormingsprosesse is waargeneem relatief tot ander beskikbare statistiese kopolimere. Die 1-penteen statistiese kopolimere toon 'n laer in-vorm sowel as totale krimping relatief tot etileen- gebaseerde kopolimere. 'n Studie het aangetoon dat tipiese bymiddelpakette by normale toevoegingsvlakke geskik is vir propileen / 1-penteen statistiese kopolimere. Gesien in die groter pp statistiese kopolimeer familie toon 1-penteen 'n beter balans van eienskappe as ander komonomere. Die kombinasie van laer smeltpunt en xileen-oplosbares met hoë moduluswaardes en helderheid is uniek aan propileen /1-penteen statistiese kopolimere.

Thesis (PhD)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: As there is inadequate control of the hydrothermal synthesis technique used to date in the synthesis of zeolite A membranes, the feasibility of a new synthesis approach was investigated, namely the static transverse synthesis method. The former technique involved (i) thorough mixing of the chemical components, (ii) gel-formation and ageing and (iii) heat treatment. The proposed new method for zeolite A synthesis concerns the use of two individual nutrient pools (AI and Si) on opposite sides of a porous medium (a-alumina tube). Diffusion of these two nutrients towards each other, due to concentration differences, results in their contact in the porous medium (crystallisation front), leading to gel formation and eventual zeolite crystal growth. By means of the new static transverse synthesis technique the application of very high nutrient concentrations (O.72g NaOH, 80.0g H20, 8.26g NaAI02 and 15.48g Na2Si03), contrary to what is used in conventional hydrothermal synthesis techniques (11.23g NaOH, 54.82g H20, 0.61g NaAI02 and 3.63g Na2Si03), is now possible. The advantage of using high nutrient concentrations lies in the fact that supersaturation exists immediately after gel formation occurs. Supersaturation is a prerequisite for grain growth, which, in tum, is the only way in which a very thin (4-6 urn), continuous (pinhole-free) zeolite crystal layers can be prepared. A variety of support materials have been used to provide the mechanical stability for zeolite membranes, because the chemical/physical interaction between a zeolite synthesis solution and the support also plays a role in the formation of a zeolite membrane. Hence, zeolite A crystal growth on four different types of supports was evaluated and the a-alumina tube proved to be the best support for zeolite A crystal growth. An exploratory study into the upgrading of the static transverse synthesis to a continuousflow synthesis was also undertaken. The nutrients were continuously passed over the opposite surfaces (internal and external) of the porous a-alumina tube. In this way the nutrients could be replenished throughout the synthesis. It was possible to make zeolite A membranes using this technique, although these membranes were not an improvement on the membranes produced with the STS method. The zeolite A crystal population in and on the surface of the porous supports was determined by scanning electron microscopy (SEM). The zeolite A crystallinity, symmetry and morphology were characterised using x-ray diffraction PCRD). The zeolite lattice vibrations, structure sensitive and structure insensitive vibrations were determined by infra red spectroscopy (IR). The wettability of the alumina support was determined by dynamic contact angle measurements. The zeolite A membranes prepared by the static transverse synthesis were tested for their helium permeance. They were also subjected to pervaporation experiments at 45°C, using a water/ethanol mixture (5 wt% water) and it was found that the fluxes varied between 0.2 -0.4 kg/m2h and the separation factors varied between 5000 and 16000. These results compare very favourably with results reported in the literature. In conclusion, the possibilities created by using a combination of membranes and catalysis, both on bench scale and in industry, are reviewed. / AFRIKAANSE OPSOMMING: Weens onvoldoende beheer oor die hitte behandeling sintese tegniek wat tans vir die sintese van zeoliet-A-membrane gebruik word, is die haalbaarheid van 'n nuwe sintese tegniek, nl. die statiese sydelingse sintese-metode, ondersoek. Eersgenoemde tegniek behels (i) deeglike vermenging van die chemiese komponente, (ii) jelvorming en -veroudering en (iii) hittebehandeling. Die voorgestelde nuwe sintese tegniek vir die bereiding van ondersteunde zeoliet-A-membrane behels die plasing van twee aparte voedingsbronne (Al en Si onderskeidelik), aan teenoorgestelde kante van 'n poreuse medium (a-aluminabuis). Diffusie van hierdie twee komponente na mekaar, agv konsentrasieverskille, veroorsaak dat die twee oplossings in die poreuse medium met mekaar in aanraking kom (kristallisasie front). Dit lei dan tot jelvorming en uiteindelik zeolietkristal groei. Met die nuwe sydelingse sintesetegniek is die aanwending van baie hoë konsentrasies van die voedingsbronne (O.72g NaOH, 80.0g H20, 8.26g NaAI02 en 15.48g Na2Si03) nou moontlik. Dit is in teenstelling met die konvensionele hitte behandelingstegnieke (11.23g NaOH, 54.82g H20, O.61g NaAl02 en 3.63g Na2Si03). Die voordeel van hoë voedingsbronkonsentrasies is dat oorversadiging onmiddelik na jelvorming bereik word. Absolute oorversadiging is 'n voorvereiste vir partikelgroei, wat op sy beurt die enigste manier is om baie dun (4-6 urn), aaneenlopende zeolietkristallae te verkry. 'n Verskeidenheid van draermateriale is al gebruik om meganiese stabiliteit aan zeolietmembrane te verleen, aangesien die chemiese/fisiese interaksie tussen die zeolietsintese-oplossing en die draermateriaal 'n rol speel in die vorming van die zeolietmembraan. Om hierdie rede is die groei van zeoliet-A-kristalle op vier verskillende tipes draermateriale ondersoek en die a-aluminabuis is as die beste draermateriaal vir zeoliet-A-kristalgroei bewys. 'n Aanvanklike studie na die moontlike opgradering van die statiese sydelingse sintese na aaneenlopende vloeisintese is ook onderneem. In hierdie studie is die voedingsbronne deurlopend oor die teenoorgestelde oppervlaktes (intern en ekstern) van die poreuse a-aluminabuis gepomp. Sodoende kon die voedingstowwe voortdurend tydens die sintese aangevul word. Dit was moontlik om zeoliet-A-membrane met behulp van hierdie tegniek te maak, alhoewel hierdie membrane nie 'n verbetering was op dié wat deur middel van die statiese sydelingse sintesetegniek gemaak is nie. Die teenwoordigheid van die zeoliet-A-kristalle op die verskillende oppervlaktes van die poreuse buis is met behulp van 'n skandeerelektronmikroskoop (SEM) bepaal. Die zeoliet-A-kristalliniteit, -simmetrie en -morfologie is met behulp van x-straaldiffraksie (XRD) gekarakteriseer. Die zeolietlatwerk-, struktuursensitiewe- en struktuuronsensitiewe vibrasies, is met behulp van infrarooispektroskopie (IR) en die benatbaarheid van die aluminabuis met dinamiese kontakhoekbepalings bepaal. Die zeoliet-A-membrane berei met die statiese sydelingse sintese-metode is vir helium-deurlaatbaarheid getoets en ook aan pervaporasie eksperimente by 45°C, deur gebruik te maak van 'n water/etanol mengsel (5 wt% water), onderwerp. Daar is gevind dat vloei tussen 0.2 - 0.4 kg/mh en dat skeidingsfaktore tussen 5000 en 16000 gevarieer het. Hierdie resultate vergelyk baie goed met die resultate in die literatuur. Samevattend word 'n oorsig gegee van die moontlikhede wat geskep word deur membraanskeidingstegnologie te kombineer met katalise op laboratorium- en industriële skaal.

Thesis (PhD)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: This dissertation describes work done on Fischer- Tropsch ionomeric waxes. The waxes are characterized with respect to the method of manufacture, the mechanism of the oxidation process, the saponification, the physical properties, the rheological properties, the morphology and the water absorption of the waxes. Different methods of physical and mechanical analysis are used to prove at which concentration level, for each type of cation tested arid for each type of oxidized and grafted wax prepared, the formation of multiplets and clusters within the Fischer- Tropsch ionomeric waxes takes place. An understanding of multiplet and cluster formation in Fischer- Tropsch ionomeric waxes is essential as these morphological phenomena control the mechanical and physical behaviour of the Fischer- Tropsch ionomeric waxes. The ability to be able to analyse the Fischer- Tropsch ionomeric waxes for multiplet and cluster formation should allow one to predict the physical and mechanical behaviour of the Fischer- Tropsch ionomeric waxes in practical applications. / AFRIKAANSE OPSOMMING: Hierdie skripsie beskryf werk gedoen op Fischer-Tropsch ionomeries wasse. Die wasse is gekarakteriseer ten opsigte van die vervaardigingsmetode, die meganisme van oksidasie, die verseping, hulle fisiese en reologiese eienskappe, hulle morfologie en water absorpsie. Verskillende metodes van fisiese en meganiese analiese is gebruik om te bewys by watter konsentrasie, vir 'n spesifieke katioon en vir 'n spesifieke geoksideerde of entwas, wanneer veelvoud of tros-vorming plaasvind. Die vermoë om te verstaan hoe en wanner veelvoude en trosse in Fischer- Tropsch ionomeries wasse vorm is van kardinale belang, aangesien die fisiese en meganiese eienskappe van die Fischer- Tropsch ionomeries wasse direk beinvloed word deur die vorming van veelvoude en trosse. Die vermoë om Fischer- Tropsch ionemeries wasse te kan analiseer vir veelvoud en tros vorming is voordelig om Fischer- Tropsch ionomeries wasse se meganiese en fisiese eienskappe in praktiese aanwendings te voorspel.

Thesis (MSc)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: This work involves the study of the effects of Reversible Addition-Fragmentation Chain Transfer (RAFT) agents on the emulsion polymerization of styrene. The feasibility of RAFT as a method for obtaining controlled radical polymerizations in emulsion systems is also investigated. Both seeded and ab initio systems were studied with three RAFT agents of varying structure. Inhibition and retardation effects on addition of various amounts of the RAFT agents to the emulsion systems were observed and the trends noticed. The effect of the RAFT agents on the average number of radicals per latex particle was calculated from reaction rates. The effect of the RAFT agent on the molecular weight and the molecular weight distribution was monitored by gel permeation chromatography. Exit of free radicals from the latex particles proves to be a major feature in the studied RAFT emulsion systems. Fragmentation of the RAFT agent in the latex particles, gives rise to free radical species that can exit from the particle and enter other particles where they can either terminate instantaneously or propagate. The exit and termination processes presumably result in both the inhibition and retardation of the emulsion polymerizations. A linear increase in Mn with conversion is observed, however the low concentration of RAFT agent in the latex particles is responsible for the obtained number average molecular weights being much higher than predicted. The low concentrations of RAFT agents in the latex particles is also responsible for the broad molecular weight distributions that are obtained. Reaction conditions for RAFT experiments should to be chosen so that the effects of exit processes are minimized and that the RAFT agent is primarily situated in the latex particles. These conditions must be met if the RAFT process is to be successful as a method of controlled radical polymerization in emulsions. / AFRIKAANSE OPSOMMING: Hierdie navorsing behels die studie van die effek van In bygevoegde addisie-fragmentasie kettingsoordragsreagent (RAFT1) op die emulsie polimerisasie van stireen. Die uitvoerbaarheid van RAFT as 'n metode om gekontroleerde radikale polimerisasies in emulsiesisteme te verkry is ook ondersoek. Eksperimente met drie RAFTkettingoordragsreagente van gevarieerde strukture is uitgevoer in beide seeded en ab initia sisteme. Die effek van die RAFT-reagent op die inhibisie en vertraging van die emulsie polimerisasie is waargeneem en die invloed van RAFT op die gemiddelde aantal radikale per partikel is bepaal. Die ontwikkeling van die molekulêre massa en die molekulêre massadistribusie is waargeneem deur middel van gel permeasie- kromatografiese tegnieke. Die ontsnapping van vrye radikale vanuit die partikels was 'n belangrike faktor in RAFT emulsiesisteme wat ondersoek is. Hierdie radikale is gegenereer deur die fragmentasie van die oorspronklike RAFT-reagent. Fragmentasie van die RAFT-reagent in die lateks partikels lei tot die vorming van vrye radikale spesies wat uit een partikel kan ontsnap en ander partikels kan binnedring waar dit onmiddellik kan termineer of propageer. Die ontsnappings- en terminasieprosesse van vrye radikale lei oënskynlik tot die inhibering en vertraging van die emulsie polimerisasie. 'n Lineêre verhoging in die gemiddelde molekulêre massa tydens konversie is waargeneem, alhoewel die Mn-waardes baie hoër was as wat verwag is. Die verskil kan toegeskryf word aan die klein hoeveelhede van die RAFT-reagent wat in die partikels teenwoordig is. Hierdie lae RAFT-konsentrasies is ook verantwoordelik vir die breë molekulêre massa distribusie wat waargeneem is. Vir die RAFT-proses om suksesvol te wees in gekontroleerde radikale polimerisasies in emulsies, moet reaksie kondisies so gekies word dat die ontsnapping van vrye radikale tot 'n minimum beperk word en die RAFT-reagent hoofsaaklik in die lateks partikels teenwoordig is.