Thesis (M.S.)--University of Missouri-Columbia, 2003. / Typescript. Includes bibliographical references (leaves 109-112). Also available on the Internet.

Thesis (M.S.)--University of Missouri-Columbia, 2003. / Typescript. Includes bibliographical references (leaves 109-112). Also available on the Internet.

Este trabalho tem como escopo o desenvolvimento de um modelo matemático representativo do processo de enxerto de anidrido maleico em polietileno, processo conhecido como grafting, com o objetivo de prever as modificações no grau de enxerto e teor de gel. Neste processo utiliza-se um iniciador, geralmente um peróxido, para gerar radicais livres, os quais abstraem hidrogênio das moléculas do polímero, gerando radicais poliméricos. O anidrido maleico pode reagir com estes radicais poliméricos, enxertando-se à cadeia polimérica, ou com os radicais fragmentos do iniciador. O mecanismo inclui também as reações de terminação entre os diferentes tipos de radicais presentes. O teor de gel é calculado a partir do grau de formação de ligações cruzadas utilizando-se a aproximação de Charlesby-Pinner. As constantes cinéticas do modelo foram estimadas via regressão não-linear, usando dados experimentais obtidos na literatura, e o modelo foi validado com outros conjuntos de dados, também obtidos da literatura. O modelo obtido mostrou-se capaz de representar adequadamente os dados experimentais em diferentes condições. / The scope of this work is the development of a mathematical model that can represent the process of grafting of maleic anhydride in polyethylene. The objective of this model is to preview the main modifications in polymer structure, as degree of grafting and degree of gel. In this process, an initiator, generally a peroxide) is used to generate free radicals that can abstract hydrogen from the polymer molecules, producing polymeric radicals. Maleic anhydride can react with these polymeric radicals, resulting in grafted polymer chains, or with the initiator radicals. This mechanism includes termination reactions between the different types of radicals present. Gel content was calculated from the crosslinking degree using the approximation of Charlesby-Pinner. Kinetic constants of the model were estimated through non-linear regression, by fitting the model to experimental data taken from literature. The model obtained was further tested using other data sets obtained from literature. The developed model was able to represent adequately the experimental data under different conditions.

Este projeto propôs a utilização de eletrodos de óxidos metálicos contendo RuO2 para realizar a eletrooxidacao do ácido maleico visando sua degradação total ou formação de produtos com menor grau de toxicidade. A oxidação de compostos fenólicos, clorados ou não, resultam em alguns produtos que interferem na mineralização completa das estruturas clorofenólicas, o ácido maleico, que é um dos principais intermediários obtidos depois da abertura do anel aromático. Os recobrimentos óxidos foram caracterizados por Microscopia Eletrônica de Varredura e Análise Dispersiva de Raios X. A caracterização eletroquímica por voltametria cíclica foi utilizada para determinação de potenciais de oxidação do acido maleico em função do eletrólito de suporte. As eletrólises foram realizadas a corrente controlada visando à melhor relação entre eficiência de corrente/degradação e melhoria no entendimento do mecanismo de oxidação. As análises quantitativas dos produtos da eletrólise foram feitas através de CLAE e a taxa de mineralização foi determinada pela quantidade de COT. Além destes dois métodos, também foram realizados testes de DQO e AOX. Os resultados mostraram que os métodos de preparação utilizados são apropriados, pois apresentaram estabilidade química, mecânica, eficiência na oxidação do ácido maleico e redução do carbono orgânico total. / This project proposed the use of metallic oxide electrodes containing RuO2 to perform the total degradation or formation of products with less toxicity. The oxidation of phenolic compounds, chlorinated or not, result in some products that interfere with complete mineralization of chlorophenol structures, the maleic acid, which is a important intermediate obtained after opening the aromatic ring. The coatings were characterized by scanning electron microscopy and X-ray dispersive analysis. The electrochemical characterization by cyclic voltammetry was used to determine the potential for the oxidation of maleic acid as a function of electrolyte support. The electrolyses were carried out at controlled current to the best ratio of efficiency of current/degration and improving the understanding of the mechanism of oxidation. The quantitative analysis of the electrolysis products were made by HPLC and the rate of mineralization was determined by the amount of TOC. Besides these two methods were also investigated COD and AOX. The results showed that the electrode preparation methods used are appropriate, showing chemical stability, mechanical efficiency in the oxidation of maleic acid and reduction of total organic carbon

Diploma thesis deals with preparation of polypropylene functionalized by maleimides, based on the reaction between maleic anhydride and amine. The overview of functionalization of polypropylene by maleic anhydride by reactive extrusion and routes for the synthesis and utilization of maleimides are contained in the theoretical part. Samples of maleimide-functionalized polypropylene were prepared by reactive extrusion using low molecular weight amines (aniline and 4-aminophenol) and hight molecular weight polyether monoamines. Functionalized polypropylene samples were prepared by several methods differing in the composition of the reaction mixture and performing a grafting reaction. Appropriate maleamic acids and maleimides were synthesized from low molecular weight amines and further used to functionalize the polypropylene. To characterize the samples, the degree of monomer conversion and melt flow index were determined and further analyses were performed by Fourier transform infrared spectroscopy, differential scanning calorimetry and thermogravimetric analysis. The synthesis of low molecular weight products was further monitored by thin layer chromatography and thermogravimetric analysis with evolved gas analysis.

It is estimated that roughly 103, 515 tons of peach waste is produced annually in the US. The majority of the waste is disposed of in landfills, which contributes to climate change as they release 93 million metric tons of CO2 equivalent. Peach waste principally consists of remaining stone and seed after flesh removal. The agro-waste includes both cellulose and lignin, which can be utilized as a filler in plastic packaging to reduce carbon footprints and material cost. The objectives of this research are (1) to develop peach flour (PF)-filled biocomposites with a polyolefin matrix using maleic anhydride-g-high density polyethylene (MAH-g-HDPE) coupling agent resin and (2) to investigate the composites’ physicomechanical, thermal, and water absorbance changes. First, preliminary experiments examined a range of PF concentrations (5-50%) and MAH concentrations (0-17%) were tested to narrow the variability of PF and MAH loading mixture in an HDPE matrix. Preliminary experiments suggested that a 2:1 ratio of PF:CR provides maximum tensile properties. Response surface methodology (RSM) was utilized to analyze and optimize the tensile strength of the PW composite. The RSM parameters were MAH loading (5-20%), PF loading (2.5-10%), and polyolefin matrix (HDPE or polypropylene). The properties of PF-HDPE biocomposites were analyzed using several instrumental analyses. Mechanical strength (including tensile strength, elongation, and Young’s modulus) and thermal properties (thermal degradation, melting point, and crystallinity), and water resistance with the addition of PF and MAH were investigated. Biocomposite mechanical properties generally resulted in a nonsignificant decrease compared to the controls. Water absorption significantly increased with PF loading (P<0.01, =0.05). PF-PP biocomposites demonstrated a shift in thermal stability with an average 9.6% increase in Td compared to its control, whereas PF-HDPE biocomposites displayed no change in Td compared to its control. PF-PP and PF-HDPE biocomposites experienced a 36.7% and 16.0% decrease, respectively, in crystallinity with PF addition. The results provided evidence that peach byproduct can be diverted from landfills and utilized a filler in a polyolefin matrix. Polyolefin biocomposites with 2.5% PF would possess comparable tensile strength to a commercially available control. PF-polyolefin biocomposites can be used for packaging, automotive, and non-weightbearing construction parts.

The preparation of a number of supported rhenium catalysts is reported. The determination of their activity and selectivity and of optimal reaction parameters for the reduction of maleic anhydride and crotonaldehyde is reported. Optimal time of hydrogenation was chosen as one hour and pressures were chosen as 2000 psig for crotonaldehyde and 3000 psig for maleic anhydride. Quantitative reduction of maleic anhydride to tetrahydrofuran occurred at 275° with charcoal supported rhenium catalysts. Lower temperatures (ca. 200°) produce quantitative amounts of butyrolactone. Unsupported catalysts at low temperatures (100°) selectively reduce crotonaldehyde to crotyl alcohol, but at very low conversion rates. Temperatures of 150° for unsupported and 180° for supported catalysts effect complete reduction of crotonaldehyde to mixtures of crotyl alcohol, butanal and butanols. Catalyst reuseability for both systems is discussed. Reaction pathways are also determined from the reduction data of intermediate products.

In the investigation the effects of excess maleic anhydride, hydrazine hydrate-solvent reagent addition time, volume of reaction mass after concentration by heating at 100 °C, mixing of reactants, and the solvent selected were studied for the heterogeneous reaction of maleic anhydride and hydrazine hydrate. A reaction time of 12 minutes was employed with the ratio of solvent to reactants held constant at 75 weight per cent throughout the tests. Solvents employed in the investigation included ethanol, methanol, isopropanol, glacial acetic acid, water, hydrachloric acid, and benzene. Atmospheric drying tests at 25 to 88 °C were employed on hydrazide slurries of free moisture content from 1.258 to 1.515 pounds of water per pound of hydrazide. Centrifuge tests at 2000 to 4700 revolutions per minute and a rotary filtration test under a 10 inch vacuum were employed on 13 weight per cent hydrazide slurries. Hydrazide filtrate evaporation tests at 100 °C were performed on samples of 18 to 1715 milliliters to determine the approximate hydrazide content in the slurries. Field applications of 0.10 to 0.22 weight per cent hydrazide solutions in water were made on "wild" varieties of briers, bermuda grass, johnson grass, milkweed, red pine, ragweed, and honey locust in the Blacksburg, Virginia, area from May to August, 1956. The yield of maleic acid hydrazide was increased from 42.6 to 67.0 per cent when the maleic anhydride excess was increased to 20 per cent in the reaction. The optimum addition time for the ethanol-hydrazine hydrate reagent to the maleic anhydride was found to be 3.8 seconds, while the optimum volume of reaction mass after concentration by beating at 100 °C was 10 to 15 milliliters for the non-agitated reactions. Agitation of the reaction mass and the solvent chosen were determined to increase the yield of the hydrazide. The optimum drying temperature and time for the drying of the hydrazide slurries were determined to be 88 °C and 75 minutes, respectively. Rotary vacuum filtration of the hydrazide slurries was determined to produce a cake free moisture of 1.33 pounds of water per pound of hydrazide as compared with 1.38 for the centrifuge test at 4700 revolutions per minute. The hydrazide content of the filtrate samples was determined to be approximately 10 to 15 per cent. Field applications on "wild" plots indicated that 40 to 80 per cent control of briers, bermuda grass, ragweed, johnson grass, and red pine could be achieved from one application of 0.10 to 0.22 weight per cent hydrazide solutions in early spring. On milkweed and honey locust growth, the spraying solution would not adhere to the leaf. A total fixed plus working capital of $1,151,740 was determined to be necessary to build a plant for the production of 242 tons of 95.5 percent pure maleic acid hydrazide per year. On this basis, a selling price of $3.00 per pound ($0.05 per gallon) would yield a 13.7 percent return as new earnings on total fixed plus working capital. / Ph. D.

Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: This study describes the synthesis and self-assembly of hetero-arm molecular brushes (hetero-arm MBs). These MBs consist of two polymeric side chains (SCs) of different natures, alternatingly distributed along the main chain (backbone). Two different types of hetero-arm MBs were prepared: first, alternating amphiphlic hetero-arm MBs (AMBs), and second, alternating hetero-arm MBs (AHMBs). Hetero-arm AMBs were synthesized via two strategies: (I) via a combination of “grafting through” and “grafting onto”, and (II) via “grafting through”. In approach (I), poly[vinyl benzyl (polyethylene glycol)-alt-N-alkyl-maleimide)] (poly[VB-(PEG12)-alt-N-(CnH2n+1)-MI]) was prepared via radical copolymerization of vinyl benzyl-terminated polyethylene glycol (VB-PEG12) with maleic anhydride (MAnh) (grafting through), which produces graft copolymers with PEG SCs and reactive succinic anhydride repeat units alternatingly distributed along the backbone. These graft copolymers were then modified by nucleophilic substitution (imidization) with alkyl amines (CnH2n+1-NH2) on the succinic anhydride residues (grafting onto). Three different primary amines possessing different alkyl chain lengths (n = 4, 12 and 16) were used in the modification process. In this way, hetero-arm AMBs with different hydrophilic to hydrophobic ratios were obtained. In approach (II), similar hetero-arm AMBs were prepared in a one-step grafting through approach. In this case, poly[VB-(PEG17)-alt-N-(CnH2n+1)-MI] (n = 10, 16 and 20) was prepared via radical copolymerization of VB-PEG17 with N-dodecylmaleimide, N-hexadecylmaleimide and N-icosylmaleimide. Following the synthesis step, self-assembly of these hetero-arm AMBs in arm-selective solvents was investigated in relation to the alkyl chain length. The morphology of the obtained assemblies was characterized by Field Emission gun-Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscopy (TEM) and Fluorescence Microscopy (a fluorescent dye was encapsulated). Cylindrical-like aggregates, length 10 μm and diameter ~ 250 nm, were obtained upon hetero-arm AMBs self-assembly. The second type of hetero-arm MBs was hetero-arm AHMBs, in which the SCs consist of PEG and poly(N,N-dimethylamino-ethyl methacrylate) (PDMAEMA). These hetero-arm AHMBs were prepared via a combination of grafting through and grafting from approaches. In this case, poly[vinyl benzyl-(polyethylene glycol)-alt-N-(poly(N,N-dimethylamino-ethyl methacrylate) maleimide] (poly[VB-(PEG17)-alt-N-(PDMAEMA)-MI) was prepared in the following steps: (1) alternating poly[vinyl benzyl-(polyethylene glycol)-alt-N-(4-hydroxyphenyl) maleimide] (poly[VB-(PEG17)-alt-N-(HPh)-MI]) was synthesized via radical copolymerization of VB-PEG17 with N-(4-hydroxyphenyl) maleimide (N-HPhMI). (grafting through), (2) the hydroxyl sites were esterified with 2-bromoisobutyryl bromide to afford poly [vinyl benzyl-(polyethylene glycol)-alt-N-(4-(2-bromobutyryloxy)phenyl) maleimide] (poly[VB-(PEG17)-alt-N-(BrPh)-MI]) (macroinitiator) and (3) an atom transfer radical polymerization (ATRP) reaction of 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA) was initiated from the obtained macroinitiator. This approach afforded poly[VB-(PEG17)-alt-N-(PDMAEMA)-MI] hetero-arm AHMBs with two water soluble SCs; however, one is water soluble at all pHs and temperatures (i.e. PEG), while the other is a pH- and temperature-sensitive polymer (i.e. PDMAEMA). Initial attempts were made to fabricate cylindrical organo/silica hybrid materials based on these AMHBs as the organic template and tetra-ethylorthosilicate as the silica precursor. Preliminary results indicate the formation of silica nano-wires, ~ 8 μm in length and ~45 nm in diameter. The self-assembly behavior of these AHMBs in water at a temperature above the lower critical solution temperature of PDMAEMA (> 55 °C) was also investigated. Fibril morphology (~ 30 nm in diameter) was observed. This study addresses initial attempts to fabricate organic/inorganic hybrid materials with controlled size and morphologies via densely grafted hetero-arm molecular brushes. / AFRIKAANSE OPSOMMING: Hierdie studie beskryf die sintese en selfsamestelling van prototipe molekulêre borsels (prototipe MBs). Hierdie MBs bestaan uit twee polimeriese sykettings (SKs) van verskillende aard wat afwisselend langs die hoofketting (ruggraat) voorkom. Twee verskillende tipes van die prototipe MBs is gesintetiseer: eerstens, afwisselende amfifiliese prototipe MBs (AMBs), en tweedens, afwisselende hetero-arm prototipe MBs (AHMBs). Prototipe AMBs is gesintetiseer d.m.v. twee strategieë: (I) deur 'n kombinasie van „enting deur‟ en „enting aan‟ benaderings, en (II) deur middel van „n „enting deur‟ benadering. In benadering (I) is poli[vinielbensiel(poliëtileenglikol)-alt-N-alkiel-maleïenamied)] (poli[VB-(PEG12)-alt-N-(CnH2n+1)-MI]) gesintetiseer deur radikaalkopolimerisasie van vinielbensiel-beëindigde-poliëtileenglikol (VB-PEG12) met maleïenanhidried („enting deur‟) wat entkopolimere produseer met PEG SKs en reaktiewe suksienanhidried herhaaleenhede wat afwisselend langs die ruggraat versprei is. Daarna is die entkopolimere gewysig d.m.v. nukleofiliese substitusie (imiedisering) met alkielamiene (CnH2n+1-NH2) op die oorblywende suksienanhidried („enting op‟). Drie verskillende primêre amiene met verskillende alkielkettinglengtes (n = 4, 12 en 16) is gebruik vir die wysigingsproses. So is prototipe AMBs met verskillende hidrofiliese tot hidrofobiese verhoudings verkry. In benadering (II) is soortgelyke prototipe AMBs gesintetiseer in 'n een-stap „enting deur‟ benadering. In hierdie geval is poli[VB-(PEG17)-alt-N-(CnH2n+1)-MI] (n = 10, 16 en 20) gesintetiseer d.m.v. radikaalkopolimerisasie van VB-PEG17 met N-dodesiel maleïenamied, N-heksadesiel maleïenamied en N-ikosiel maleïenamied. Na afloop van die sintese stap is die selfsamestelling van hierdie prototipe AMBs in spesifieke oplosmiddels in verhouding tot die alkielkettinglengtes ondersoek. Die morfologie van die versamelings is gekarakteriseer deur veld-emissie-geweer-(Eng: field emission gun-)-skandeerelektronmikroskopie (FE-SEM), transmissie-elektronmikroskopie (TEM) en fluoresserende mikroskopie („n fluoresserende kleurstof is ingesluit). Silinderagtige versamelings (lengtes ~10 μm en deursnee ~250 nm) is deur die selfsamestelling van prototipe AMBs verkry. Die tweede soort prototipe MBs is prototipe AHMB, waarin die SKs uit PEG en poli(N,N-dimetielaminoetiel metakrilaat) (PDMAEMA) bestaan. Hierdie prototipe AHMBs is d.m.v. 'n kombinasie van „enting deur‟ en „enting van‟ benaderings gesintetiseer. In hierdie geval is poli[vinielbensiel-(poliëtileenglikol)-alt-N-(poli(N,N-dimetielaminoetiel metakrilaat) maleïenamied] (poli[VB-(PEG17)-alt-N-(PDMAEMA)-MI) gesintetiseer deur van die volgende stappe gebruik te maak: (1) sintese van afwisselende poli[vinielbensiel-(poliëtileenglikol)-alt-N-(4-hidroksifeniel) maleïenamied] (poli[VB-(PEG17)-alt-N-(HPh) -MI) deur midel van radikaalkopolimerisasie van VB-PEG17 met N-(4-hidroksifeniel) maleïenamied (N-HPhMI) („enting deur‟), (2) esterifikasie van die hidroksielgroepe met 2-bromoisobutiriel bromied om poli[vinielbensiel-(poliëtileenglikol)-alt-N-(4-(2-bromobutirieloksi) feniel) maleïenamied] (poli[VB-(PEG17)-alt-N-(BrPh)-MI]) (makro-afsetter) te berei, en (3) die atoomoordrag-radikaalpolimerisasie reaksie van 2-(N,N-dimetielamino)etiel metakrilaat (DMAEMA) wat begin is vanaf die gevormde makro-afsetter. Hierdie benadering gee poli[VB-(PEG17)-alt-N-(PDMAEMA)-MI] prototipe AHMBs met twee wateroplosbare SKs, waarvan een wateroplosbaar is by alle pHs en temperature (d.w.s. PEG), terwyl die ander tipe SK „n pH- en temperatuur-sensitiewe polimeer is (d.w.s. PDMAEMA). Aanvanklike pogings is aangewend om silindriese organo/silika hibriedmateriale te sintetiseer, gebaseer op hierdie AHMBs as die organiese segment en tetraëtielortosilikaat as die silika voorloper. Die voorlopige resultate dui op die vorming van silikananodrade, lengte ~8 μm en deursnit ~45 nm. Die selfsamestellingsgedrag van hierdie AHMBs is ook in water ondersoek by 'n temperatuur hoër as die laer kritieke oplossingstemperatuur van PDMAEMA (> 55 °C). „n Draadagtige morfologie (deursnit ~30 nm) is waargeneem. Hierdie studie beskryf aanvanklike pogings om organiese–anorganiese hibriedmateriale met beheerde groottes en morfologieë via dig-geënte hetero-arm molekulêre borsels te vervaardig.

As a preliminary starting point for the present study, physical and mechanical properties of polypropylene nanocomposites (PPNCs) for samples received from Queen's University Belfast have been evaluated. Subsequently, polymer/clay nanocomposite material has been produced at Bradford. Mixing and processing routes have been explored, and mechanical properties for the different compounded samples have been studied. Clay intercalation structure has received particular attention to support the ultimate objective of optimising tensile and fracture behaviour of isotropic and die-drawn PPNCs. Solid-state molecular orientation has been introduced to PPNCs by the die-drawing process. Tensile stress-strain measurements with video-extensometry and tensile fracture of double edge-notched tensile specimens have been used to evaluate the Young's modulus at three different strain rates and the total work of fracture toughness at three different notch lengths. The polymer composite was analyzed by differential scanning calorimetry, thermogravimetric analysis, polarizing optical microscopy, wide angle x-ray diffraction, and transmission electron microscopy. 3% and 5% clay systems at various compatibilizer (PPMA) loadings were prepared by three different mixing routes for the isotropic sheets, produced by compression moulding, and tensile bars, produced by injection moulding process. Die-drawn oriented tensile bars were drawn to draw ratio of 2, 3 and 4. The results from the Queen's University Belfast samples showed a decrement in tensile strength at yield. This might be explained by poor bonding, which refers to poor dispersion. Voids that can be supported by intercalated PP/clay phases might be responsible for improvement of elongation at break. The use of PPMA and an intensive mixing regime with a two-step master batch process overcame the compatibility issue and achieved around 40% and 50% increase in modulus for 3% and 5% clay systems respectively. This improvement of the two systems was reduced after drawing to around 15% and 25% compared with drawn PP. The work of fracture is increased either by adding nanoclay or by drawing to low draw ratio, or both. At moderate and high draw ratios, PPNCs may undergo either an increase in the size of microvoids at low clay loading or coalescence of microvoids at high clay loading, eventually leading to an earlier failure than with neat PP. The adoption of PPMA loading using an appropriate mixing route and clay loading can create a balance between the PPMA stiffness effect and the degree of bonding between clay particles and isotropic or oriented polymer molecules. Spherulites size, d-spacing of silicate layers, and nanoparticles distribution of intercalated microtactoids with possible semi-exfoliated particles have been suggested to optimize the final PPNCs property.