Made available in DSpace on 2014-10-09T12:54:49Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:07:33Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:54:49Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:07:33Z (GMT). No. of bitstreams: 0 / Como conseqüência da operação de uma unidade de purificação de tório para a produção de nitrato de tório puro, o Instituto de Pesquisas Energéticas e Nucleares (IPEN) armazenou um resíduo rico em terras raras contendo tório e pequeno teor de urânio. Este resíduo é registrado como RETOTER (Resíduo de Tório e Terras Raras). O resíduo contém os radioisótopos naturais das séries do urânio e do tório. Contribuição radioativa significativa é dada pelos descendentes do tório, especialmente o rádio-228 (T1/2 = 5,7 anos) comumente conhecido como mesotório e o tório-228 (T1/2 = 1,90 anos). Um descendente do tório de muito interesse e presente com teor razoável é o chumbo-208, um isótopo estável. A partir do encerramento das atividades da planta de purificação de tório, os técnicos do IPEN vêm trabalhando no estabelecimento de tecnologia de aproveitamento do tório, das terras raras e do chumbo-208 contidos no RETOTER. O presente trabalho consiste em dissolver o RETOTER com ácido nítrico separando e confinando os contribuintes radioativos, especialmente o rádio-228, por coprecipitação com sulfato de bário. Em seguida o tório foi separado por precipitação como peróxido. As terras raras presentes no filtrado, foram recuperadas como peróxido de terras raras. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN/CNEN-SP

Orientador: Débora Alves Nunes Leite Lima / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-23T00:08:03Z (GMT). No. of bitstreams: 1 D'Arce_MariaBeatrizFreitas_D.pdf: 1270067 bytes, checksum: 7681e880d0d8a3c1dc2b3f8cfa2af016 (MD5) Previous issue date: 2013 / Resumo: O objetivo deste estudo foi avaliar a mudança de cor do esmalte e dentina após clareamento com géis de alta e baixa concentração em diferentes temperaturas. Cinquenta fragmentos dentais bovinos foram pigmentados em uma solução de chá preto. As amostras foram distribuídas aleatoriamente em 10 grupos (n=5) de acordo com o protocolo de clareamento: peróxido de carbamida 10% (PC) 4h/dia por 21 dias; peróxido de hidrogênio 6% (PH) com cálcio 1:30h/dia por 21 dias; PH 20% com cálcio 50 min/sessão com intervalo de 7 dias (3 sessões); HP 35% Blue com cálcio 40 min/sessão com 7 dias de intervalo (3 sessões); HP 35% Maxx 3x15 min/sessão com intervalo de 7 dias (3 sessões), e da temperatura de 22ºC e 41ºC. As amostras foram armazenadas em saliva artificial durante o todo experimento. A mudança de cor foi avaliada por meio de um espectrofotômetro (Konica Minolta CM 700d, Japan) e os dados expressos nos valores do sistema CIE Lab. As leituras de cor do esmalte e dentina foram feitas após a pigmentação e após o final de cada semana de clareamento. Ainda, a superfície de esmalte de 3 amostras de cada grupo foram avaliadas por meio de Microscopia Eletrônica de Varredura (MEV). Para a coordenada L*, os dados foram analisados por medidas repetidas e teste de Tukey-Krammer (5% de nível de significância) e os valores de ?E foram submetidos ao teste ANOVA 2 way e teste de Tukey (5% de nível de significância). Não houve diferença estatística significante entre as temperaturas avaliadas de 22ºC e 41ºC. À 22ºC, o PH 20% com cálcio mostrou os menores médias de reflectância diferindo estatisticamente de PC 10% e PH 6% com cálcio nas superfícies de esmalte e dentina. À 41ºC, nenhuma diferença estatística entre os agentes clareadores foi observada após três semanas de tratamento. O peróxido de hidrogênio 20% com cálcio foi menos efetivo na temperatura ambiente no esmalte e na dentina. Entretanto, a temperatura de 41ºC melhorou a eficácia deste agente clareador. Foram observadas alterações morfológicas na superfície de esmalte após o uso dos agentes clareadores, sendo que as maiores alterações ocorreram nos grupos tratados com géis com baixo pH / Abstract: The aim of this study was to evaluate the enamel and dentin color changes after bleaching using low- and high-concentration gels at different temperatures. Fifty bovine teeth fragments were stained in a black tea solution. The samples were randomly placed in 10 groups (n=5) according to the bleaching protocol: 10% carbamide peroxide (CP) 4h/day for 21 days; 6% hydrogen peroxide (HP) with calcium 1.30h/day for 21 days; 20% HP with calcium 50 min/session with seven-day intervals (3 sessions); 35% HP Blue with calcium 40 min/session with seven-day intervals (3 sessions); 35% HP Maxx 3x15 min/session with seven-day intervals (3 sessions), and a gel temperature of 22ºC and 41ºC. The samples were stored in artificial saliva at all times during the experiment. Color change effectiveness was evaluated using a spectrophotometer (Konica Minolta CM 700d, Japan) and data was expressed in CIE Lab System values. The enamel and dentin color measurements were made after staining and at the end of each week of bleaching sessions. In addition, three enamel surface samples from each group were evaluated using a scanning electronic microscope (SEM). For the L* coordinate, data was analyzed by repeated-measures and Tukey-Krammer Test (5% significance level) and ?E values were submitted to ANOVA 2-ways and Tukey tests (5% significance level). There were no statistical differences between the evaluated temperatures 22ºC and 41ºC. At 22ºC, the 20% HP with calcium showed the lowest reflectance means differing statistically from 10% CP and 6% HP with calcium on the enamel and dentin surfaces. At 41ºC, no statistical difference among bleaching agents was observed after three weeks of treatment. The 20% hydrogen peroxide with calcium was less effective at room temperature on enamel and dentin. However, the temperature at 41ºC improved the efficacy of this bleaching agent. Morphology changes on enamel surface were observed after using the bleaching agents, being more pronounced in the groups treated with low pH gels and high-concentration agents / Doutorado / Dentística / Doutora em Clínica Odontológica

Over the past few years the number of deaths caused due to cardiovascular diseases has been increasing and is of major concern. In the United States, 75% of cardiovascular-related deaths have been attributed to atherosclerosis. Western diets containing large quantities of peroxidized lipids are considered atherogenic. Heated oil in the form of fried food brings high levels of peroxidized fat and its decomposition products in the diet. Peroxidized lipids are known to increase the susceptibility of serum lipoproteins to undergo oxidation, thereby contributing to the progression of atherosclerosis. The intestinal cells are responsible for the absorption of dietary fatty acid peroxides (FAOOH) which has been reported to enhance anti-atherosclerotic effects by inducing apolipoprotein A1 (apoA1) gene and protein levels. Therefore, there is a void in the knowledge of when to expect “harmful” or “beneficial” effects of dietary lipid peroxides. The formation of toxic products like aldehydes from the decomposition of FAOOH is well documented. On the other hand, carboxylic acids particularly azelaic acid, formed as an end product of FAOOH decomposition has been reported to have anti-atherosclerotic effects. Hence, we hypothesize that intestinal cells may decompose FAOOH to aldehydes, which might get converted to carboxylic acids that can be transported across the intestine. Linoleic acid is the most abundant polyunsaturated fatty acid (PUFA) present in the diet. So, we will use peroxidized linoleic acid (13- HPODE) and incubate with intestine derived cells or Caco-2 cells as an in-vitro model for determining its decomposition to aldehydes and carboxylic acids. We propose that the decomposition products of FAOOH in the presence of intestinal cells might be iv responsible for causing an increase in apoA1 levels, which might suggest that lipid peroxidation derived products might actually be beneficial for reducing the progression of atherosclerosis as compared to the absorption of intact FAOOH.

Ganoderma lucidum is one of most popular medicinal mushrooms in oriental countries. The medicinal properties of Ganoderma lucidum in the treatment of various diseases have been documented for hundreds of years. In recent years, more and more attentions are paid on the studies of the action mechanisms of bioactive compounds purified from this mushroom. / In conclusion, the Ganoderma steroids EP and 9(11)-DHEP can induce caspase-dependent apoptosis in susceptible cancer cells via the mitochondria-mediated pathway. In vitro and in vivo studies suggested that these two fungal steroids have the potential to be used as natural chemopreventive agents. / Keywords: Ergosterol peroxide, 9(11)-dehydroergosterol peroxide, Ganoderma lucidum, Mycelia, Antitumor activity, Apoptosis / The antiproliferative activities of EP and 9(11)-DHEP were studied by flow cytometry. Exposure of cancer cells with these two fungal steroids resulted in an accumulation of cell population at the subG1 phase in a dosage- and time-dependent manner, indicating the induction of apoptotic cell death. Morphological apoptotic changes in HepG2 cells and A375 cells were observed using TUNEL assay and Annexin-V-FLUOS assay. The signaling pathway in apoptotic cell death induced by EP and 9(11)-DHEP involved the activation of caspase 3, 7 and 9, followed by the cleavage of PARP. In Colo201 cells, a change in the ratio of expression levels of Bcl-2/Bax was observed in cells treated with EP and 9(11)-DHEP. In A375 cells, exposure to EP and 9(11)-DHEP resulted in the release of mitochondrial cytochrome c, the down-regulation of Mcl-1 and a slight up-regulation of Bak in a dosage-dependent manner. All these results indicated that apoptotic cell death in susceptible cancer cells induced by EP and 9(11)-DHEP was via the mitochondria-mediated pathway. / The in vivo antitumor activity of EP was demonstrated. EP was shown to suppress the growth of A375 cells in a nude mice xenograft model. Further studies showed that EP induced the cleavage of PARP and enhanced the total caspase 7 gene expression in the tumor cells. / Triterpenes and steroids are two important classes of Ganoderma lucidum metabolites of low molecular mass that are responsible for the antitumor activities of the mushroom. In this study, two fungal steroids, namely, 5alpha,8alpha-epidioxy-22E-ergosta-6,22-dien-3beta-ol (ergosterol peroxide (EP)) and 5alpha,8alpha-epidioxy-22E-ergosta-6,9(11),22-trien-3beta-ol (9,11-dehydroergosterol peroxide (9(11)-DHEP)) were purified from the mycelia of Ganoderma lucidum grown under submerged culture using activity-guided purification procedures against human breast adenocarcinoma MCF-7 cells. In addition to MCF-7 cells, both of these two fungal steroids showed antiproliferative activities against other human cancer cells including hepatocellular carcinoma HepG2 cells, colorectal carcinoma Colo201 cells, esophageal squamous carcinoma KYSE cells and malignant melanoma A375 cells. However, EP and 9(11)-DHEP were less toxic to MCF-10-2A, non-tumorigenic human epithelial cells, and the normal human skin fibroblast Hs68 cells. / Zheng, Lin. / Adviser: Y. S. Wong. / Source: Dissertation Abstracts International, Volume: 71-01, Section: B, page: 0253. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 153-176). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese.

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Heterophasic ethylene-propylene copolymers, also known as impact polypropylene (PP) copolymers (IPCs) or heterophasic copolymers (HECOs), are a unique group of polyolefins produced through the copolymerisation of ethylene and propylene, with the aim of improving the impact properties of the PP homopolymer at low temperatures. Therefore, this polymer comprises of a PP homopolymer matrix with a dispersed rubbery copolymer phase. Due to their unique properties, HECO polymers have become commercially important materials, with a wide range of applications. Therefore a fundamental understanding of the processes and chemistry that affects their final macroscopic properties needs to be expanded. The main focus of this investigation was to understand why specific organic peroxides influence or interact differently with the various phases of HECO polymers, in order to utilize their properties to obtain HECO polymers with optimal and desired properties. Two HECO polymers with different ethylene contents were fractionated into three fractions (30, 100 and 130 °C), using preparative temperature rising elution fractionation (P-TREF). Each individual TREF fraction was degraded with two different types of organic peroxides, and then characterised using four different analytical tools. The changes in the molecular structures of the different fractions were investigated by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The changes in comonomer sequence distributions were investigated by carbon 13 nuclear magnetic resonance spectroscopy (13C-NMR). Moreover, the degradation of the different fractions was investigated by high temperature size exclusion chromatography (HT-SEC). The investigation showed that the HECO polymers with different ethylene contents were uniquely altered. It was evident that the ethylene content influenced the degradation behaviour of the HECO polymers. The ability of the peroxide to affect certain regions of the HECO polymer more than others is highly dependent upon its miscibility with certain regions of the HECO polymers. The “visbreaking” efficiency of a specific organic peroxide appears to be primarily dependent on the number of “peroxy” groups it contains in its molecular structure. Stellenbosch University https://scholar.sun.ac.za / AFRIKAANSE OPSOMMING: Heterofase etileen-propileen ko-polimere, ook bekend as impak PP ko-polimere (IPCS) of heterofase ko-polimere (HECO), is 'n unieke groep poliolefiene geproduseer deur die ko-polimerisasie van etileen en propileen, met die doel op die verbetering in die impak eienskappe van die PP homopolimeer by lae temperature. Hierdie polimeer bestaan dus uit 'n PP homopolimeer matriks met 'n verspreide rubberagtige ko-polimeer fase. As gevolg van hul unieke eienskappe, is HECO polimere van kommersiële belang, met 'n wye verskeidenheid van toepassings. 'n Fundamentele begrip van die prosesse en chemie wat die finale makroskopiese eienskappe beïnvloed moet dus uitgebrei word. Die hooffokus van hierdie ondersoek was om te verstaan waarom spesifieke organiese peroksiede verskillende invloede en interaksies met die verskillende fases van HECO polimere het, om sodoende van hul eienskappe gebruik te maak om HECO polimere te verkry met optimale en gewenste eienskappe. Twee HECO polimere met verskillende etileen inhoud was gefraksioneer in drie fraksies (30, 100 en 130 °C), met behulp van preparatiewe temperatuur styging eluering fraksionering (P-TREF). Elke individuele TREF fraksie was gedegradeer met twee verskillende tipes organiese peroksiede en daarna gekarakteriseer deur vier verskillende analitiese metodes. Die veranderinge in molekulêre strukture van die verskillende fraksies was geondersoek met behulp van Fourier transform infrarooi spektroskopie (FTIR) en differensiële skandering kalorimetrie (DSC). Die veranderinge in ko-monomeer volgorde distribusie was bestudeer deur middel van kern magnetiese resonans spektroskopie (KMR). Verder was die degradasie van die verskillende fraksies met behulp van hoë temperatuur grootte uitsluitingschromatografie (HT-SEC) bestudeer. Die ondersoek het getoon dat die HECO polimere met verskillende etileen inhoud uniek gedegradeer was. Dus is dit duidelik genoeg dat die etileen inhoud die degradasie gedrag van die HECO polimere beïnvloed het. Die vermoë van die peroksied om sekere areas van die HECO polimeer meer as ander te beïnvloed is hoogs afhanklik van die mengbaarheid met sekere areas van die HECO polimere. Die "visbreking" doeltreffendheid van 'n spesifieke organiese peroksiede is meestal afhanklik van die aantal "peroksie" groepe in die molekulêre struktuur.

Problématique : Le glutathion est une molécule clé de la défense antioxydante. Chez les enfants sous nutrition parentérale (NP), particulièrement les nouveau-nés, sa concentration tissulaire est anormalement basse. Puisque la capacité de synthèse de glutathion est adéquate, un déficit en cystéine, le substrat limitant, est soupçonnée. À cause de son instabilité en solution, la cystéine est peu présente en NP; la méthionine étant le précurseur endogène de cet acide aminé. L’activité de la méthionine adénosyltransférase (MAT), une enzyme essentielle à la transformation de la méthionine en cystéine, est facilement inhibée par l’oxydation. L’hypothèse : Le faible taux de glutathion chez les enfants sous NP est causé par l’inhibition de la MAT par les peroxydes contaminant ces solutions nutritives. Objectif: Mesurer l’impact d’une infusion de NP et de H2O2 sur l’activité hépatique de MAT en relation avec le niveau de glutathion. Méthode : Un cathéter est placé dans la jugulaire droite de cobayes de trois jours de vie. Quatre groupes sont comparés:1- Témoin (animaux aucune manipulation, sans cathéter) 2)-(animaux nourris normalement et le cathéter (noué)); 3) NP (animaux nourris exclusivement par voie intraveineuse (acides aminés + dextrose + lipides + vitamines + électrolytes), cette solution génère environ 400 µM de peroxyde. 4) H2O2 (animaux nourris normalement et recevant via le cathéter 400 µM de H2O2). Après quatre jours, le foie et le sang sont prélevés pour la détermination du glutathion, potentiel redox et l’activité de MAT, glutathion peroxydase et glutathion reductase. Résultats : L’activité de MAT est plus faible dans les groupes NP et H2O2. Le potentiel redox du foie et dans le sang est plus oxydé dans le groupe NP. Tandis que la concentration de GSSG du foie est plus élevée dans le groupe NP. Ainsi la concentration de GSH dans le sang et foie est plus faible dans les NP et H2O2 Discussion: La relation entre l’inhibition de MAT et le stress oxydant observée dans le groupe NP pourrait bien expliquer la perturbation du système glutathion observée chez les nouveau-nés prématurés. / Introduction: The low glutathione level in premature newborns can partly explain the high incidence of complications associated with oxidative stress in this population. Since the synthetic activity of glutathione is mature, a lack of substrate, especially cysteine, is suspected. Methionine provided by their parenteral nutrition (PN) is the in vivo precursor of cysteine. Since, methionine adenosyltransferase (MAT), the first enzyme in methionine transformation, has redox sensitive cysteines, we hypothesize that peroxides contaminating PN inhibit the activity of MAT, leading to a lower availability of cysteine for glutathione synthesis. Methods: At 3 days of life, guinea pigs a catheter fixed in jugular vein, the animals were separated in 4 groups: 1) Control: animals without any treatment and no catheter 2) sham: animals fed regular chow, a node closed their catheter; 3) PN: animals fed exclusively with parenteral nutrition (dextrose, amino acids, fat, vitamins) containing about 400 µM peroxides; 4) H2O2: animals fed regular chow and received continuously 400 µM H2O2 through the catheter. Four days later, liver and blood were sampling for determination of reduced glutathione (GSH), oxidized glutathione (GSSG), redox potential and activities of MAT, glutathione peroxidase, and glutathione reductase. Results: MAT activity was lower in groups receiving PN or H2O2. Liver redox was more oxidized in PN group whereas blood redox was more oxidized in PN and H2O2. Liver and blood GSH is lower in PN and H2O2. Liver GSSG was higher in PN. Conclusion: The inhibition of MAT in the PN group could explain the disruption of the glutathione system observed in premature infants. Furthermore the impact of a lower activity of MAT on GSH level is observed in liver and blood. Suggesting that the hepatic synthesis of GSH is insufficient to maintain its own level of glutathione and sustain the rate of export.

Problématique : Le glutathion est une molécule clé de la défense antioxydante. Chez les enfants sous nutrition parentérale (NP), particulièrement les nouveau-nés, sa concentration tissulaire est anormalement basse. Puisque la capacité de synthèse de glutathion est adéquate, un déficit en cystéine, le substrat limitant, est soupçonnée. À cause de son instabilité en solution, la cystéine est peu présente en NP; la méthionine étant le précurseur endogène de cet acide aminé. L’activité de la méthionine adénosyltransférase (MAT), une enzyme essentielle à la transformation de la méthionine en cystéine, est facilement inhibée par l’oxydation. L’hypothèse : Le faible taux de glutathion chez les enfants sous NP est causé par l’inhibition de la MAT par les peroxydes contaminant ces solutions nutritives. Objectif: Mesurer l’impact d’une infusion de NP et de H2O2 sur l’activité hépatique de MAT en relation avec le niveau de glutathion. Méthode : Un cathéter est placé dans la jugulaire droite de cobayes de trois jours de vie. Quatre groupes sont comparés:1- Témoin (animaux aucune manipulation, sans cathéter) 2)-(animaux nourris normalement et le cathéter (noué)); 3) NP (animaux nourris exclusivement par voie intraveineuse (acides aminés + dextrose + lipides + vitamines + électrolytes), cette solution génère environ 400 µM de peroxyde. 4) H2O2 (animaux nourris normalement et recevant via le cathéter 400 µM de H2O2). Après quatre jours, le foie et le sang sont prélevés pour la détermination du glutathion, potentiel redox et l’activité de MAT, glutathion peroxydase et glutathion reductase. Résultats : L’activité de MAT est plus faible dans les groupes NP et H2O2. Le potentiel redox du foie et dans le sang est plus oxydé dans le groupe NP. Tandis que la concentration de GSSG du foie est plus élevée dans le groupe NP. Ainsi la concentration de GSH dans le sang et foie est plus faible dans les NP et H2O2 Discussion: La relation entre l’inhibition de MAT et le stress oxydant observée dans le groupe NP pourrait bien expliquer la perturbation du système glutathion observée chez les nouveau-nés prématurés. / Introduction: The low glutathione level in premature newborns can partly explain the high incidence of complications associated with oxidative stress in this population. Since the synthetic activity of glutathione is mature, a lack of substrate, especially cysteine, is suspected. Methionine provided by their parenteral nutrition (PN) is the in vivo precursor of cysteine. Since, methionine adenosyltransferase (MAT), the first enzyme in methionine transformation, has redox sensitive cysteines, we hypothesize that peroxides contaminating PN inhibit the activity of MAT, leading to a lower availability of cysteine for glutathione synthesis. Methods: At 3 days of life, guinea pigs a catheter fixed in jugular vein, the animals were separated in 4 groups: 1) Control: animals without any treatment and no catheter 2) sham: animals fed regular chow, a node closed their catheter; 3) PN: animals fed exclusively with parenteral nutrition (dextrose, amino acids, fat, vitamins) containing about 400 µM peroxides; 4) H2O2: animals fed regular chow and received continuously 400 µM H2O2 through the catheter. Four days later, liver and blood were sampling for determination of reduced glutathione (GSH), oxidized glutathione (GSSG), redox potential and activities of MAT, glutathione peroxidase, and glutathione reductase. Results: MAT activity was lower in groups receiving PN or H2O2. Liver redox was more oxidized in PN group whereas blood redox was more oxidized in PN and H2O2. Liver and blood GSH is lower in PN and H2O2. Liver GSSG was higher in PN. Conclusion: The inhibition of MAT in the PN group could explain the disruption of the glutathione system observed in premature infants. Furthermore the impact of a lower activity of MAT on GSH level is observed in liver and blood. Suggesting that the hepatic synthesis of GSH is insufficient to maintain its own level of glutathione and sustain the rate of export.

Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Heterophasic copolymers (also known as HECO polymers) or often referred to only as impact copolymers or block copolymers comprise a polymer matrix with a dispersed rubbery copolymer phase. The polymer under investigation in this study consists of a polypropylene homopolymer matrix and ethylene-propylene copolymers (EPCs). Due to its diverse range of applications and unique properties, polypropylene is the choice of polymer for a vast array of applications. This has led to the development of an entire class of polypropylene materials known as visbroken or controlled rheology polypropylene. By adding a suitable peroxide to the polymer in the presence of heat, radicals are formed which will attack the polymer chains in a random fashion. The resultant polymers generally have a higher melt flow rate (MFR), a narrower molecular weight distribution than the parent polymer, and good impact-stiffness balance. The main focus of this investigation was to determine if there exist any differences in the molecular structure and physical properties of controlled rheology HECO polymers and if differences do exist, how they influence the physical characteristics of the polymer. Eight HECO polymers with equal ethylene contents were visbroken to varying degrees by making use of two different types of organic peroxide. The effects of the amount of visbreaking on the molecular characteristics and physical properties were subsequently studied by making use various types of fractionation techniques, including preparative temperature rising elution fractionation (PTREF) and crystallisation analysis fractionation (CRYSTAF). Subsequent offline analysis was then done on the fractionated samples that included nuclear magnetic resonance spectroscopy (NMR), differential scanning calorimetry (DSC), high temperature size exclusion chromatography (HT-SEC), Fourier transform infrared spectroscopy (FTIR) and deposition of the SEC fractions via the LC Transform Interface (SEC-FTIR) as well as high temperature high performance liquid chromatography (HT-HPLC), a novel technique for the characterization of olefins according to their chemical composition. / AFRIKAANSE OPSOMMING: Heterofase kopolimere, ook bekend as HECO polimere, of dikwels na verwys net as impak kopolimere of blok kopolimere bestaan uit 'n polimeer matriks met 'n verspreide rubberagtige kopolimeer fase. Die polimeer wat in hierdie studie ondersoek was het bestaan uit 'n polipropileen homopolimeer matriks en etileen-propileen kopolimere (EPCs). As gevolg van sy veelseidigheid van toepassings en unieke eienskappe is polipropileen die keuse van polimeer vir 'n wye verskeidenheid van toepassings. Hierdie veelseidigheid het gelei tot die ontwikkeling van 'n hele klas van polipropileen materiaal bekend as gevisbreekte of beheerde reologie polipropileen. Deur die byvoeging van 'n geskikte peroksied tot die polimeer in die teenwoordigheid van hitte, word radikale gevorm wat die polimeerkettings in 'n ewekansige wyse sal aanval. Die gevolglike polimere in die algemeen het 'n hoë smelt vloeitempo (MFR), 'n smaller molekulêre gewig verspreiding as die moeder polimeer, en 'n goeie impak/styfheid balans. Agt HEKO polimere met gelyke etileen inhoude was gevisbreek in wisselende hoeveelhede deur gebruik te maak van twee verskillende tipes organiese peroksiedes. Die gevolge van die hoeveelheid van visbreeking op die molekulêre eienskappe en fisiese eienskappe was vervolgens gebestudeer deur gebruik te maak van verskillende fraksionasie tegnieke, insluitend preparatiewe TREF (P-TREF) en CRYSTAF. Daaropvolgende analiese is gedoen op die gefraktioneerde monsters en sluit in kernmagnetiese resonansie spektroskopie (KMR), differensiële skandeer kalorimetrie (DSC), 'n hoë temperatuur grootte uitsluitings chromatografie (HT-SEC), Fourier transform infrarooi spektroskopie (FTIR) met deponeering van die SEC fraksies via die LC transform koppelvlak (SEC-FTIR) sowel as 'n hoë temperatuur hoë werkverrigting vloeistof chromatografie (HT-HPLC), 'n nuwe tegniek vir die karakterisering van olefiene volgens hul chemiese samestelling.

No description available.