Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2006. / This study concerns the polymerization of propylene both in the presence and absence of molecular hydrogen. The percentage of hydrogen used as a terminating agent in the polymerization reactions was varied from 0.1 wt% to 15.0 wt% in order to compare a variety of polymers with different percentages of hydrogen incorporated. Two ansa metallocene catalysts were used: (A) rac-[ethylene bis(indenyl)] zirconium dichloride (rac-Et(Ind)2ZrCl2) and (B) dimethylsilyl-bis(2-methyl benzoindenyl) zirconium dichloride (rac-Me2Si(2-MeBenz[e]Ind)2ZrCl2). Methylaluminoxane (MAO) was used as cocatalyst for both of the two catalysts. Characterization of the polymers included using nuclear magnetic resonance spectroscopy (NMR) for information concerning the microstructure of the polymers, high temperature gel permeation chromatography (HT-GPC) for molecular weight and molecular weight distributions and differential scanning calorimetry (DSC) to investigate the melting point and crystallization behaviour of the polymers. The polypropylenes prepared with the dimethylsilyl-bis(2-methyl benzoindenyl) zirconium dichloride catalyst system were compared to the polypropylenes synthesized with ethylene-bis(indenyl) zirconium dichloride. In particular, the effects of hydrogen on the microstructure, molecular weight, molecular weight distribution, melting point and crystallization behaviour were investigated.

Thesis (MSc)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: The surfmers sodium l l-rnethacryloyloxy undecanyl-I sulfate (MET) and sodium 11- crotonoyloxy undecanyl-I sulfate (CRO) were synthesized and purified. Both contain a sulfonate and polymerizable double bond connected by a hydrocarbon chain. Sodium 4-[ 11- (3-carboxypropionoyloxy)-undecyloxy] benzenesulfonate (PSA-MA) could not be synthesized successfully. MET and CRO were characterized by means of nuclear magnetic resonance spectroscopy (NMR), elemental analysis (EA), thermal gravimetric analysis (TGA), determination of the critical micelle concentration (CMC), differential scanning calorimetry (DSC), and microscopy. MET and CRO displayed a liquid crystalline behavior. MET and CRO were used in combination with poly(diallyl dimethyl ammonium chloride) to form polyelectrolyte-surfactant complexes by common precipitation in water. These complexes were redissolved in methanol and cast in films. The cast films were investigated by wide angle X-ray scattering (WAXS) and small angle X-ray scattering (SAXS) with regard to ordered mesomorphous phases. Due to the destabilization of the lyotropic phase, little order were observed in the complexes. MET was co-polymerized with styrene and methyl methacrylate, in different proportions, by means of free radical polymerization. The co-polymers were characterized by NMR and infrared spectroscopy (Ik) and analyzed by DSC, TGA and gel permeation chromatography (GPC). All analytical techniques showed that the co-polymers were synthesized successfully. TEM indicated a fine, lamellar micro-structure. / AFRIKAANSE OPSOMMING: Die polimeriseerbare sepe, natrium-ll-metakrieloloksi-undekaniel-l sulfaat (MET) en natrium-ll-krotonieloksi-undekaniel-l-sulfaat (CRO) is berei en gesuiwer. Beide bevat 'n sulfonaat en 'n polimeriseerbare dubbelbinding wat deur 'n koolwaterstofketting verbind word. Natrium-4-[11-(3-karboksipropionieloksi)-undekieloksi]-benseensulfaat (PSA-MA) kon nie suksesvol berei word me. MET en CRO is deur middel van kernmagnetieseresonansspektroskopie (KMR), elementele-analise (EA), termiesegravimetriese analise (TOA), kritiese miselkonsentrasie (CMC), differensieelskandeerkalorornetrie (DSC) en mikroskopie gekarakteriseer. Beide MET en CRO het 'n vloei-kristalgedrag getoon. MET en CRO is met poli(diallieldimetielammoniumchloried) gereageer om polyelektrolietseepkompleks te vorm deur presipitasie uit water. Die komplekse is in metanol opgelos en films daarvan gemaak. Die films is deur wyehoek X-straal diffraksie (WAXS) en kleinhoek X-straaldiffraksie (SAXS) ondersoek om geordende mesomorfiese fases te ondersoek. As gevolg van destabilisasie van die liotropiese fase is min orde in die komplekse gevind. MET is met stireen en metielmetakrilaat deur middel van vryeradikaalpolymerisasie gekopolimeriseer. Die kopolimere is deur middel van KMR- en infrarooispektroskopie (IR), DSC, TOA en gelpermeasiechromotagrafie (OPC) ondersoek. Al hierdie analitiese metodes het die suksesvolle sintese van die kopolimere bewys. Transmissie-elektronmikroskopie het die teenwoordigheid van 'n fyn, laminere mikro-struktuur bewys.

Thesis (MSc)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: Controlled free radical polymerisation techniques offer several practical and theoretical advantages compared to many other polymerisation techniques. Living polymerisation techniques such as anionic polymerisations require the total exclusion of impurities such as oxygen and moisture. Controlled free radical polymerisations, however, do not require such stringent methods of practice. This is very advantageous for industrial purposes. Atom Transfer Radical Polymerisation (ATRP) is a form of a controlled/living free radical polymerisation technique by which one is able to synthesize controlled architectural structures and predetermine the molecular weights of macromolecules. The monomers that were investigated for this research project include methyl methacrylate (MMA), 4-vinylpyridine (4VP) and lauryl methacrylate (LMA). The latter two monomers (4VP and LMA) are not commonly used in ATRP-mediated reactions. The synthesis of block copolymers ofMMA and LMA were attempted. The homopolymerisation of 4VP did not give the control expected when polymerising by means of ATRP. This prompted an investigation into possible side reactions that could take place with 4VP in this specific ATRP system. This included possible quatemization of 4VP with the alkyl halide initiator species. / AFRIKAANSE OPSOMMING: Beheerde vrye-radikaalpolimerisasietegnieke bied verskeie praktiese en teoretiese voordele bo verskeie ander vrye-radikaalpolimerisasietegnieke. Lewende polimerisasietegnieke soos anioniese polimerisasie, vereis die totale uitsluiting van onsuiwerhede soos suurstof en water. Beheerde vrye-radikaalpolimerisasies vereis egter nie sulke streng reaksiekondisies nie. Hierdie is baie voordelig vir industriële doeleindes. Atoomoordragradikaalpolimerisasie (ATRP) is 'n tipe beheerde/lewende vryeradikaalpolimerisasietegniek wat dit moontlik maak om die samestelling en struktuur van makromolekules asook die molekulêre massa presies te beheer. In hierdie studie is die monomere metielmetakrilaat (MMA), 4-vinielpiridien (4VP) en laurielmetakrilaat (LMA) bestudeer. Laasgenoemde twee monomere (4VP en LMA) word beskou as ongewone monomere om in ATRP-sisteme te gebruik. Daar is gepoog om blok kopolimere van MMA en LMA te sintetiseer. Die homopolimerisasie van 4VP het minder beheer gelewer as wat by beheerde vrye-radikaal sisteme soos hierdie verwag word. Na aanleiding van hierdie resultate is 'n ondersoek geloods om die moontlike newereaksies van 4VP in hierdie spesifieke ATRP-sisteem te ondersoek. Daar is gepoog om te bewys dat die alkielchloriedinisieerder verdwyn deur kwatemisasie met 4VP.

Thesis (MSc)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: This study describes the design, building and optimization of a fully functional preparative TREF (Prep-TREF) apparatus. This apparatus allows for the fractionation of semicrystalline polyolefins according to the crystallizability of the molecules. Various factors, such as the sample cooling rate and the effect of on-support and off-support crystallization, are investigated. The preparative TREF is used to fractionate a commercial low-density polyethylene (LOPE), two commercially available plastomers (polyethylene-l-octene copolymers), as well as blends of the LOPE and the respective plastomers. It is shown that in each case the samples fractionated by crystallizability. The fractions recovered from the Prep-TREF were characterized by CRYSTAF, OSC and NMR analysis. It is shown how the results of this preparative fractionation allow for a better understanding of the molecular heterogeneity in the LOPE and plastomers. New ways of presenting the data from the preparative fractionation, in terms of 3- dimensional plots, are also investigated. These plots offer a novel way of presenting the molecular heterogeneity in the samples in terms of the molecular crystallizability. These plots highlight features that are difficult to detect in the conventional two-dimensional plots. In conclusion, the influences of various blending ratios of LOPE and plastomer on the morphological and physical properties of the blends, such as haze, clarity, and tear-and impact strength are determined. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie was die ontwikkeling en optimisering van 'n ten volle funksionerende TREF. Hierdie tegniek word gebruik om polimeermengsels te fraksioneer deur gebruik te maak van die kristaliseerbaarheid van polimere. Verskeie faktore soos die afkoel spoed en die effect van met en sonder 'n ondersteuning(seesand) vir kristaliseering was ondersoek. Hierna is navorsing gedoen om 'n beter begrip ten opsigte van die meganiese, fisiese en optiese eienskappe van lae-digtheid poliëtileen (LDPE) te ontwikkel. Hierdie LDPE is met die affiniteitsreeks plastomere van die maatskappy, Dow Chemicals, gemeng om tendense in die gefraksioneerde polimere te indentifiseer. Een van Sasol se kommersiële LDPE produkte en twee van Dow Chemicals se plastomere is individueel gefraksioneer. Die mengsel van die twee ongefraksioneerde LDPE en plastomere is nog nooit voorheen op 'n molekulêre basis ondersoek nie. Dit is in hierdie studie gedoen deur van TREF gebruik te maak. Nuwe maniere is ontwikkel om data op 'n nuwe manier voor te stel deur middel van 3 Dimensionele grafieke te skep om resultate voor te stel wat andersins baie moelilik was om voor te stel in een dimensie agv die hoeveelheid data wat geinterpreteer word. Ten slotte is die invloed van die verskillende mengverhoudings van LDPE en plastomere op die morfologiese en fisiese eienskappe soos deursigtigheid, helderheid, skeur- en impaksterkte, ook ondersoek.

Thesis (DSc (Chemistry and Polymer Science))--University of Stellenbsoch, 2006. / The synthesis and characterization of a new tertiary alcohol (2-octyl-2-dodecanol) and “bushy-tailed”, hydrophobic acrylic monomer (2-octyl-dodecyl acrylate) from a 1-decene dimer (2-octyl-1-dodecene) precursor that was synthesized with metallocene technology is reported. Some preliminary applications of the newly synthesized 2-octyl-dodecyl acrylate were investigated. These applications included the use of 2-octyl-dodecyl acrylate as a reactive hydrophobe in mini-emulsion polymerizations, and as a reactive (internal) plasticizer. In an attempt to selectively dimerize 1-decene, the effect of various factors on the oligomerization of 1-decene was investigated. These factors include the following: i. Different temperatures: 5, 35, 70 and 90°C ii. Different co-catalyst [methylaluminoxane (MAO)] concentrations iii. Different catalysts: bis(cyclopentadienyl)zirconium dichloride (Cp2ZrCl2) and bis(cyclopentadienyl)hafnium dichloride (Cp2HfCl2) iv. Different reaction times. In all instances the final product obtained, under the abovementioned conditions, was a mixture of residual monomer, the dimer and trimer of 1-decene. These findings were corroborated with GC-MS and 1H-NMR spectroscopy. The isolation and further processing of the dimer of 1-decene (2-octyl-1-dodecene) was investigated. The efficiency, in terms of the final product-composition for the amount of catalyst used and reaction time, of Cp2ZrCl2 compared to bis(cyclopentadienyl)hafnium dichloride (Cp2HfCl2; hafnocene) as catalyst for the oligomerization of 1-decene is also reported on. The results obtained indicated that Cp2ZrCl2 is the more efficient catalyst for the oligomerization of 1-decene. The effect of different reaction times (1, 3, 6, 24 hours) on the final product-composition for the oligomerization of 1-decene was also investigated. Longer reaction times (24 hours) seemed to be excessive. A reaction time of 6 hours was optimal. The purified 1-decene dimer (2-octyl-1-dodecene) was converted to the new tertiary alcohol (2-octyl-2-dodecanol) using the oxymercuration-demercuration procedure. The 2-octyl-dodecyl acrylate was synthesized by the esterification of the tertiary alcohol with acryloyl chloride in the presence of triethylamine. The new tertiary alcohol and acrylate were characterized by FT-IR and 1H-NMR spectroscopy. Stable polymer latex particles were successfully synthesized with the novel reactive hydrophobe 2-octyl-dodecyl acrylate in the mini-emulsion polymerization of butyl acrylate, methyl methacrylate and styrene. Phase-separation experiments showed that the presence of 2-octyl-dodecyl acrylate in the dispersed phase retards Ostwald ripening. The novel acrylic monomer, 2-octyl-dodecyl acrylate, was copolymerized with styrene via conventional free radical polymerization. Both low and high molecular weight copolymers were prepared. Thermal analysis of the copolymers showed that 2-octyl-dodecyl acrylate does act as a reactive (internal) plasticizer. Blends of commercial virgin polystyrene and the synthesized low and high molecular weight copolymers were prepared. Partially miscible blends were obtained. Decreases in the glass transition temperatures of the blends compared to the virgin polystyrene were observed. The higher molecular mass styrene/2-octyl-dodecyl acrylate copolymers produced larger decreases in glass-transition temperatures.

Thesis (DSc (Chemistry and Polymer Science))--University of Stellenbosch, 2005. / Aqueous polyurethane (PU) dispersions were synthesized for use in paper coatings. These PUs contained a polyester polyol soft segment (content of between 65 to 75%) and a urethane hard segment (content of between 30 to 35%). Triethylamine (TEA) was used as the neutralizing agent. The polyester polyol segment consisted of neopentyl glycol (NPG), adipic acid, 1,4-cyclohexane dicarboxylic acid (1,4-CHDCA) and 2-phosphonobutane- 1,2,4-tricarboxylic acid (PBTCA), while the urethane hard segment consisted of toluene diisocyanate (TDI), dimethylolproponic acid (DMPA) and ethylene glycol (EG) as a chain extender for increasing the hard segment content. Waxes and fillers were incorporated into the PU coating mixtures to investigate their effect on the barrier properties of the PU. Two types of fillers were used: nano-fillers and micro-fillers. The nano-fillers used included the Cloisite nano-clays NC15A, NC93A and NC30B, and the micro-fillers used included talc, kaolin clay and barium sulfate. Two different polyester polyols were synthesized: one containing a phosphate and the other containing no phosphate. The polyols were characterized in terms of their acid value, hydroxyl value and molecular mass. The PUs synthesized from the polyol containing no phosphate showed unfavourable barrier properties compared to results achieved with the phosphate-containing PU. The PU dispersions were applied to paperboard, and then dried at a maximum temperature of 130oC for 15 to 60 seconds, depending on the coating volume. The PU-coated paperboard was characterized primarily by determining the moisture vapour transmission rate (MVTR), and by scanning electron microscopy (SEM). PU films (stand alone, not supported by paper) were prepared by heating the concurrent PU dispersion in Teflon holders over three different temperature stages (60, 90 and 120oC) for about 2 days. The dried films were then characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy. The PU coatings showed self-assembly properties, which were affected primarily by the ionic content (comprising of DMPA, PBTCA and excess TEA) and emulsion viscosity. These self-assembly properties were analyzed by static contact angle (SCA) and MVTR measurements. It was found that the final coating properties were affected by the self-assembly mechanism of the PU. Generally, the phosphated PU coatings had lower MVTR values than the non-phosphated PU coatings. SEM analysis showed that the phosphated PU coatings had no pinholes, while the non-phosphated PU coatings had pinholes. DMA analysis showed that the phosphated PUs had higher Tg values than the non-phosphated PUs. Further, the inclusion of the phosphate monomer increased the emulsion stability and the compatibility between the hard and soft segments of the PU. Also, the exfoliated PU nanocomposites at 1% filler loading gave much better MVTR results compared to the PU microcomposites. It also rendered the coating to be non-blocking, with minimal change in MVTR.

Thesis (DSc (Chemistry and Polymer Science))--University of Stellenbosch, 2006. / Commercial polyolefins degrade under the influence of light, heat, chemical and mechanical factors. They are therefore stabilised to ensure that they maintain performance characteristics during their service life. Degradation results in changes in the molar mass, molar mass distribution, chemical composition and chemical composition distribution. Classical analytical techniques only provide averaged values of these properties. Much information is available in the open literature on the changes in molar mass, molar mass distribution and chemical composition of polypropylene upon degradation, but no information was available on the changes in chemical composition distribution (CCD) during degradation. This study describes the use of the following analytical techniques to study this: temperature rising elution fractionation (TREF), crystallisation analysis fractionation (CRYSTAF) and coupled size exclusion chromatography-Fourier transform infrared analysis (SEC-FTIR). The CRYSTAF results complimented those obtained by classical techniques: there was a broadening of the crystallisation peak (CCD), an increase in the soluble fraction and a decrease in crystallisation temperatures. SEC-FTIR analysis showed that most of the degraded products were concentrated in the low molar mass regions. TREF analysis was used to separate a degraded sample into fractions of different degrees of degradation. It was then possible to study the spatial heterogeneity in a thick, degraded polypropylene sample using SEC, FTIR and CRYSTAF. The degradation behaviour of selected Sasol propylene-1-pentene random copolymers was investigated. CRYSTAF, SEC-FTIR and TREF analyses provided information on the thermo-oxidative degradation behaviour differences between unstabilised polypropylene homopolymers and these propylene-1-pentene copolymers. It was found that the pentene copolymers degraded significantly faster compared to the homopolymers, even at low levels of pentene (< 3%). The reduction in stability was virtually linear with an increase in pentene content (up to 8 mol% pentene), indicating that higher levels of primary stabilisers are needed to ensure similar life spans for the Sasol propylene-1-pentene copolymers. The extrusion stability of the propylene-1-pentene copolymers was, however, similar to that of the polypropylene homopolymers, indicating that similar processing stabiliser packages may be used.

Thesis (PhD (Chemistry and Polymer Science))--University of Stellenbosch, 2006. / Propylene/1-pentene random copolymers are a relatively new family of random copolymers being prepared by Sasol Polymers and reveals high impact strength, good tensile properties, excellent optical properties, good rheological properties and a large pool of processing possibilities. These commercial copolymers are being prepared with stereospecific heterogeneous Ziegler-Natta catalytic systems containing multiple active sites and therefore producing copolymers with a varying degree of stereoregularity. Two different groups of propylene/1-pentene random copolymers were received by Sasol Polymers and investigated in this project. The first group (Group 1, Polymers A - F) consisted of six totally different batches of commercial propylene/1-pentene copolymers which were produced by different catalyst systems. All had different melt flow indices (MFIs) and different 1-pentene contents and all of the copolymers, except for one, were nucleated. The second group (Group 2, Polymers G - J) were produced by the same catalyst, but with varying donor:catalyst ratios and also differing in their 1-pentene content. Investigation of the Group 1 copolymers was used in order to construct a “molecular toolbox” which was then used to study the Group 2 copolymers. The original commercial copolymers were all studied by various analytical techniques: high-temperature carbon thirteen nuclear magnetic resonance spectroscopy (13C-NMR), high-temperature gel permeation chromatoghraphy (HT-GPC), crystallization analysis fractionation (CRYSTAF), differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD) and positron annihilation lifetime spectroscopy (PALS). The random copolymers were all fractionated by preparative TREF and the fractions analyzed utilizing the following analytical techniques: 13C-NMR, HT-GPC, CRYSTAF and DSC. The results of these analyses were used to investigate inter alia the distribution of 1-pentene in the copolymers. In order to investigate the low molecular weight material of the copolymers, which were part of the room temperature fraction during TREF, solvent extractions were carried out using different solvents and different extraction techniques. A complete structural analysis study was carried out on the extracts. The percentages of xylene-solubles were also determined during the quantitative xylene extraction study of the copolymers. Characterization of the xylene non-soluble material was carried out using 13C-NMR, HT-GPC, CRYSTAF, DSC and WAXD in order to compare the properties of the unextracted copolymers with the material after removal of the xylene soluble fraction. Positron annihilation lifetime spectroscopy (PALS) was used as an alternative investigation method for the Group 1 copolymers and their XNS fractions in order to determine what type of information this novel analytical method could generate and how the results compared with those of previous PALS studies on poly-olefins. A new fractionation technique, preparative solution fractionation (SF), was developed and evaluated. The commercial propylene/1-pentene copolymers were fractionated using this novel technique, the fractions were analyzed by 13C-NMR, HT-GPC, CRYSTAF and DSC and the results were compared with previously existing fractionation methods, namely TREF and CRYSTAF. A final study was done on the random copolymers by blending one of the commercial Ziegler-Natta catalyzed propylene/1-pentene copolymers with a tailored, low 1-pentene content, metallocene propylene/1-pentene copolymer in different ratios. The blends were analyzed by molecular weight, thermal and crystal phase analysis in order to investigate the effect of the tailored, highly isotactic propylene/1-pentene copolymer on the properties the commercial random copolymers. Throughout the project the influence of the 1-pentene as well as the donor:catalyst ratio on the copolymers was investigated. This study, in its entirety, therefore allow a better understanding of the effects that the commercial, heterogeneous, transition metal catalysts have on the make up of the copolymers and, by extension, the ultimate properties of the materials.

Thesis (PhD (Chemistry and Polymer Science))--University of Stellenbosch, 2009 / Polypropylene is an extremely versatile material and has a broad spectrum of applications due to the variations in properties which are possible with this material. The variations in the properties of the material are governed by the microstructure of the chains constituting the polymer. The microstructure varies according to the production methods, i.e. the polymerisation conditions. Varying the manner in which the polymer is produced therefore changes the properties of the material allowing the polymers’ use for different applications. The most important factor affecting the way in which the polymers are produced is the nature of the active sites on the catalyst. Changing the chemical environment of the active sites changes the way in which the polymerisation is controlled and greatly affects the types of chains produced and thus polymer properties. The study examines the structure-property relationships of polyolefins with specific focus on the polypropylene homopolymer. The temperature rising elution fractionation (TREF) technique is used extensively in order to isolate specific fractions of the polymer. The importance of specific TREF fractions is investigated via a two pronged investigative methodology. On the one hand specific TREF fractions are removed from a sample, allowing the analysis of the properties of the material without that specific fraction, thereby revealing the influence which the fraction in question has on the properties. The other branch of the study investigates the chemical modification of the active sites of a Ziegler-Natta catalyst so as to be able to modify the properties of the polymer in the reactor, in a similar manner to physically removing fractions. The techniques are related and it was discovered that the amount of the fractions of the polymer, found to be important using the one technique, also turned out to be important using the other method. Initial method development work utilised a polypropylene-1-pentene copolymer since the molecular heterogeneity of this material is such that large differences are observed upon removal of fractions. The technique was then applied to a Ziegler-Natta catalysed polypropylene homopolymer. Each TREF fraction is successively removed and the residual material analysed. Specific TREF fractions were found to play a significant role in determining the polymer properties since there was a drastic reduction in properties upon removal of these fractions. The polymerisation of propylene was also performed at a variety of conditions in order to investigate different ways in which the catalyst system could be modified. Specific reaction conditions were chosen for in-depth analysis and structure-property correlation. The chemical modification of the active sites was accomplished via the introduction of an external Lewis base (electron donor) to the polymerisation system, and also by varying the external donor/catalyst ratio used. Two different external donors were used during the study namely Diphenyl-dimethoxysilane (DPDMS) and methyl-phenyl-dimethoxysilane (MPDMS). It is observed that there are definite links between the amounts of specific fractions present in the polymer and the polymer properties, as observed via both the physical removal of fractions and the chemical modification of active sites.

Thesis (PhD)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: Metalloxycarbene complexes [(CO)5M1=O(R)M2(Cl)L2] (M1 = Cr , W; M2 = Zr, Hf; L = Cp, Cp*) were synthesized from the reaction between anionic Fischer-type carbene complex salts [(CO)5M1=C(O)R][NEt4] and metallocene chlorides. The molecular and crystal structures of [(CO)5W=C(Me)OZr(Cp)2Cl], [(CO)5Cr=C(Me)OZr(Cp)2Cl] and [(CO)5W=C(Ph)OHf(Cl)Cp2] determined by X-ray methods, show a short Ccarbene-O and relatively long O-Zr and O-Hf separations. Metalloxycarbene complexes in the presence of MAO are active catalysts for homo- and copolymerization of -olefins and produce polymers with heterogeneous properties. 1-Pentene oligomers, homopolymers of ethylene and ethylene/1-pentene copolymers were successfully synthesized using metalloxycarbenes/MAO and the results obtained were critically compared with those synthesized with metallocene/MAO catalysts. The GC and GPC show that 1-pentene oligomers produced with both metalloxycarbenes and metallocenes catalysts range from simple dimers to more complicated high molecular weight (2 600 g/mol) products. The properties of polyethylene and ethylene/1-pentene copolymers were evaluated by, among others, GPC, SEC-FTIR, preparative molecular weight fractionation and HPer DSC. Generally the polymers obtained using metalloxycarbene/MAO catalysts have broad and bimodal molecular weight distributions. The copolymers have higher concentration of 1- pentene in the lower molecular weight fraction than those produced with metallocene/MAO as shown by SEC-FTIR. Consequently, HPer DSC shows a decrease of melting and crystallization temperature towards the low molecular weight fractions. / AFRIKAANSE OPSOMMING: Metaaloksikarbeenkomplekse [(CO)5M1=C(R)OM2(Cl)L2] (M1 = Cr , W; M2 = Zr, Hf; L = Cp, Cp*] is gesintetiseer in die reaksie tussen anioniese Fischer-tipe karbeenkomplekssoute, [(CO)5M1=C(O)R][NEt4], en metalloseen dichloriedes. Die molekulêre- en kristalstrukture van [(CO)5W=C(Me)OZr(Cp)2Cl], [(CO)5Cr=C(Me)OZr(Cp)2Cl] en [(CO)5W=C(Ph)OHf(Cl)Cp2] bepaal deur X-straalkristallografiese metodes, toon die aanwesigheid van kort Ckarbeen-O- en relatief lang O-Zr- en O-Hf-bindings. Metaaloksikarbeenkomplekse, in die aanwesigheid van MAO, is aktiewe katalisatore vir die homo- en ko-polimerisering van α-olefiene en is verantwoordelik vir die vorming van polimere met heterogene eienskappe. 1-Penteen oligomere, homopolimere van etileen en etileen/1-penteen ko-polimere is suksesvol gesintetiseer met metaaloksikarbeenkomplekse/MAO en die resultate sodoende verkry, is krities vergelyk met produkte gesintetiseer vanuit metalloseen/MAO prekatalisatore. Die GC en GPC resultate toon dat die 1-penteen oligomere, geproduseer met beide metaaloksikarbeenkomplekse en metallosene, kan wissel van eenvoudige dimere tot meer komplekse, hoë molekulêre massa (2 600g/mol) produkte. Die polietileen en etileen/1- penteen ko-polimere is gekarakteriseer deur onder andere gevorderde, GPC, SEC-FTIR, preparatiewe molekulêre massa fraksionering en HPer DSC. In die algemeen het die polimere verkry met metaaloksikarbeen/MAO katalisatore, breë en bimodale molekulêre massaverspreidings. Die ko-polimere bevat hoër konsentrasies van 1-penteen in die lae molekulêre massa fraksie in vergelyking met dié gevorm vanuit metalloseen/MAO–gekataliseerde mengsels, soos aangedui deur SEC-FTIR-analise. HperDSC wys 'n verlaging in smelt- en kristallisasietemperature in die laer molekulêre massa fraksies.