The aim of this study is to investigate the effects of compatibilizers, fumed silica and mixing order of components on morphological, thermal, mechanical and flow properties of LDPE/Fumed silica nanocomposites. As compatibilizer(Co) / ethylene/n-butyl acrylate/maleic anhydride (E-nBA-MAH), ethylene/glycidyl methacrylate (E-GMA) and ethylene/methyl acrylate/glycidyl methacrylate (E-MA-GMA) Lotader&reg / resins / as silica Cab-o-sil&reg / M5 fumed silica were used. All samples were prepared by means of a lab scale co-rotating twin screw extruder and injection molded into standard samples. In the first step, individual effects of filler and compatibilizers were studied in binary systems with LDPE. Then, keeping the amount of compatibilizer constant at 5%, ternary nanocomposites were prepared by adding 2 or 5% of fumed silica using different component mixing orders. Among investigated mixing orders, mechanical test results showed that the best sequences of component addition are FO1 [(LDPE+Co)+M5] and FO2 [(LDPE+M5)+Co] mixing orders. Considering the compatibilizers, E-nBA-MAH terpolymer showed the highest performance in improving the mechanical properties, E-GMA copolymer also gave satisfactory results. According to the DSC analysis, since addition of fumed silica and compatibilizer does not influence the crystallization behavior of the compositions, it is concluded that, neither fumed silica nor any of the compatibilizers have nucleation activity on LDPE. MFI test results showed that, addition of fumed silica increases the melt viscosity, decreasing MFI values of samples. This change seems to be directly proportional to fumed silica amount.

In this study, 20/80 (weight %) Poly(ethylene terephthalate) (PET) /High Density Polyethylene (HDPE) Microfibrillar Reinforced Composites (MFC) were prepared by using high density polyethylene (HDPE) as the matrix material, poly(ethylene terephthalate) (PET) as the reinforcing component. Ethylene n-butyl acrylate-glycidyl methacrylate (E-nBA-GMA) and ethylene methyl acrylate (E-MA) as the compatibilizers in 1, 5, and 10 wt. %. The objective of this study is to produce MFCs based on PET and HDPE via extrusion-drawing-injection method and to characterize as extruded, as drawn and injection molded materials in terms of morphologies, and mechanical and thermal properties. In addition, the effect of compatibilizer type and content on properties of PET-HDPE composites was studied. For comparison purposes, conventional PET-HDPE composites with and without compatibilizer were prepared. Also, the effect of screw speed and drawing speed on the morphologies and mechanical and thermal properties were investigated. The effect of low and high injection temperature molding on morphologies were also observed. SEM analyses showed that, extruded blends became oriented after drawing. The fibrillar structure was preserved after injection molding. High injection molding temperature destroyed the structure of PET microfibers. In addition, it was also observed that the adhesion between HDPE and PET improved with the addition of the compatibilizers. Tensile strength and tensile modulus values of PET/HDPE MFCs increased with increasing drawing speed. Increasing the screw speed resulted in a slight decrease in tensile strength values. Addition of the compatibilizers to the system decreased tensile strength and tensile modulus values. Results of impact tests designated that the impact strength of the materials with and without MFC structure increased with the increasing amounts of E-nBAGMA. DSC analyses pointed out that, melting temperatures of HDPE and PET phase did not change significantly with increasing drawing speed or with the addition of the compatibilizer. As the drawing speed increased from 2.7 m/min to 6.2 m/min, degree of crystallinity of the drawn samples of the PET phase increased.

The objective of this study is to investigate the effects of titanate coupling agents on low density polyethylene (LDPE) and polypropylene (PP) blends and composites in terms of their mechanical and morphological properties. PP and LDPE composites were produced separately in a Brabender internal mixer, and CaCO3 was used as inorganic filler with compositions of 20, 40 and 60 %. PP/LDPE blends were produced in a twin-screw extruder with ratios of 75/25, 50/50 and 25/75. Their composites were prepared with addition of untreated and titanate-treated CaCO3 at 20% filler content. Titanate coupling agent which is appropriate for LDPE, PP and CaCO3 was used to improve the mechanical properties of the blends and composites. For this purpose, &ldquo / Lica 12&rdquo / which is a kind of neoalkoxy organotitanate was used. Two forms of Lica 12 were used: powder form (Capow L12) and pellet form (Caps L12). Samples with and without titanate were prepared and then they were injection molded to make specimens for tensile and impact tests. Tensile fracture surfaces of samples were examined by scanning electron microscopy (SEM). Their mechanical and morphological properties were compared with each other to determine the effects of Lica 12. This study showed that Capow L12 improved strain at break and impact strength of PP/CaCO3 composites and PP/LDPE blends containing 75% and 50% PP. The strain at break value of of PP75 composite with 20% titanate-treated filler increased significantly up to 509% which is the highest value among all blends and composites in this study. Capow L12 exhibited its functions in PP matrix much more effectively than in LDPE matrix.

Plastic materials are widely used throughout the world due to their low prices and easy processing methods. A serious problem of environmental pollution is brought with the widespread use of these materials due to their non-biodegradabilty. For this reason, plastic materials are degraded into lower molecular weight liquid and gaseous products which are potential raw materials and fuels for petrochemical industry. The use of catalysts enhances the formation of more valuable hydrocarbons at lower reaction temperatures and residence times. In this study, aluminum containing MCM-41 and tungstophosphoric acid (TPA) loaded SBA-15 materials were synthesized by impregnation of Al and TPA into hydrothermally synthesized MCM-41 and SBA-15, respectively to be used in catalytic degradation of polyethylene. Al was incorporated into MCM-41 framework with different Al/Si ratios using aluminum triisopropylate as the aluminum source and TPA was incorporated to the porous framework of SBA-15 with different W/Si ratios, using tungstophosphoric acid hydrate as the acid source. From XRD analysis, it was observed that introducing acidic compounds did not cause deformations in the regularity and by EDS analysis, it was found out that at lower loadings, acidic compounds were introduced more effectively for MCM-41 materials. Nitrogen adsorption-desorption isotherms showed that the synthesized materials exhibited type IV isotherms. SEM and TEM pictures showed the hexagonal regularly ordered structure of SBA-15 and MCM-41 materials. FTIR analysis of the pyridine adsorbed synthesized materials revealed the existence of Lewis and Br&oslash / nsted acid sites in the synthesized materials. From TGA analysis it was observed that aluminum impregnated MCM-41 samples reduced the temperature of the degradation reaction significantly and TPA loaded SBA-15 samples reduced activation energy of the reaction effectively. In the degradation reaction system, non-catalytic and catalytic degradation experiments of polyethylene were performed. In non-catalytic degradation and catalytic degradation reactions carried out using aluminum containing MCM-41 materials, selectivity of C3 and C4 hydrocarbon gases was high and in catalytic degradation reactions carried out using TPA impregnated SBA-15 materials, selectivity of ethylene was high. In the liquid analysis of non-catalytic degradation reactions, it was observed that the product distribution was mainly composed of hydrocarbons greater than C18. The use of aluminum loaded MCM-41 and TPA loaded SBA-15 materials resulted in a liquid product distribution in the range of C5-C14, which is the hydrocarbon range of gasoline fuel.

The property transition metal nanoclusters are more active catalysts than their bulk counterparts because of increasing proportion of surface atoms with decreasing paricle size. The development of efficient and economical catalysts to further improve the kinetic properties under moderate conditions is therefore important for the practical application of nanoclusters as catalyst in the hydrogen generation from hydrolysis of ammonia borane this. In this regard, the development of active iron catalysts is a desired goal because it is the most ubiquitous of the transition metals, the fourth most plentiful element in the Earth&rsquo / s crust. In this dissertation, we report the preparation, characterization and investigation of the catalytic activity of the water soluble polymer stabilized iron(0) nanoclusters. They were prepared from the reduction of iron(III) chloride by a mixture of sodium borohydride (NaBH4, SB) and ammonia borane (H3NBH3, AB) mixture in the presence of polyethylene glycol (PEG) as stabilizer and ethylene glycol as solvent at 80 &deg / C under nitrogen atmosphere. PEG stabilized iron(0) nanoclusters were isolated from the reaction solution by centrifugation and characterized by SEM, EDX, TEM, HRTEM, XRD, UV-Vis, ICP-OES and FT-IR techniques. PEG stabilized iron(0) nanoclusters have almost uniform size distribution with an average particle size of 6.3 &plusmn / 1.5 nm. They were redispersible in water and yet highly active catalyst in hydrogen generation from the hydrolysis of AB. They provide a turnover frequency of TOF = 6.5 min-1 for the hydrolysis of AB at 25.0 &plusmn / 0.5 &deg / C. The TOF value is the best ever reported among the Fe catalyst and comparable to other non-noble metal catalyst systems for the catalytic hydrolysis of AB. Kinetics of hydrogen generation from the hydrolysis of AB in the presence of PEG stabilized iron(0) nanoclusters were also studied by varying the catalyst concentration, substrate concentration, and temperature. This is the first kinetic study on the hydrolysis of AB in the presence of an iron catalyst. Moreover, PEG stabilized iron(0) nanoclusters can be separated magnetically from the catalytic reaction solution by using a magnet and show catalytic activity even after tenth run.

Polyethylene (PE) is one of the most popular polymers used in daily life. However, saturated hydrocarbons cannot absorb the energy of light reaching to earth, so degradation process is rather slow which in return cause disposal problems. On the other hand, it was observed that in presence of oxygen and impurities in the polymer matrix, degradation can be rendered to shorter time intervals. This study covers investigation of effect of three different additives in UV induced oxidative degradation of polyethylene. In this work vanadium (III) acetylacetonate, serpentine and Cloisite 30B were used as additives both together and alone to follow photodegradation of polyethylene. Amount of vanadium (III) acetylacetonate was kept constant at 0.2 wt%, while serpentine and Cloisite 30B were used between 1 and 4 wt%. All compositions were prepared by using Brabender Torque Rheometer, and shaped as thin films by compression molding. Samples were irradiated by UV light up to 500 hours. Mechanical and spectroscopic measurements were carried out in certain time intervals to monitor the degradation. It can be concluded that all combinations of three additives showed the fastest degradation behavior compared to pure PE. In the absence of vanadium (III) acetylacetonate the degradation was slowed and fluctuations were observed in the residual percentage strain at break values. There was not a significant change in tensile strength of all samples. Carbonyl index values followed by FTIR were always in increasing manner. Thermal properties were also investigated by DSC Thermograms and they did not change significantly.

This thesis focuses on the development of new compounds or new processes that are more environmentally friendly and economical than those currently in use. The decomposition of hydrazine, a well established liquid rocket fuel for both the aerospace and defense industries, to the product ammonia is studied. Control of this reaction will allow hydrazine to be used as a propellant for both chemical and electric propulsion. From this a dual stage thruster will be developed that will be more efficient than current systems decreasing the amount of propellant needed and allowing for either a larger mission payload or a longer duration of individual missions. Hydrazine, while beneficial and well established, is also highly toxic, so other work in this thesis focuses on the synthesis of the novel molecule 1,1-dimethyl-2-[2-azidoethyl]hydrazine or DMAEH and its hydrazone intermediate 1,1-dimethyl-2-[2-azidoethyl]hydrazone or De-DMAEH as less toxic hydrazine replacements. Novel "switchable" ionic liquids have been investigated in this research. These are solvents that can change from molecular liquids to ionic liquids and back, simply with the addition or removal of CO₂ from the system. They can be used for a variety of applications, including as solvents for a reaction and separation system. Due to the recyclable nature of these solvents, waste is decreased making their development and implementation both environmentally and economically beneficial. Finally, the grafting reaction of vinyl silanes onto a hydrocarbon backbone is investigated. Fundamental work is being performed to study the graft distribution, selectivity and mechanism by which this reaction occurs. A more thorough understanding of how this reaction proceeds will allow for the development of a more efficient industrial process.

The research discussed in this dissertation was conducted to understand drop formation of inkjet printing with inks containing polymer. Solutions containing a water soluble polymer, poly ethylene oxide (PEO), with different molecular weights and polydispersities were used as inks. A flash photographic technique was used to visualize the whole process of DOD drop formation of dilute polymer solutions. The effects of driving signal, frequency and liquid properties on drop speed, drop size, breakup time and the formation of satellites were studied in detail. The addition of PEO increases the shear viscosity at all molecular weights, but the change is small for dilute solutions. However, the addition of a small amount of PEO can have a significant effect on the DOD drop formation process, increasing breakup time, decreasing primary drop speed and decreasing the number of satellites in some cases. The effects depend on both molecular weight and concentration. At lower molecular weights (14k and 35k g/mol), the effect of PEO was small when the drop formation process for the dilute solution was compared with that of a Newtonian liquid having similar shear viscosity, and the effect of PEO was small even at concentrations large enough that the solution does not fall in the dilute regime. As molecular weight is increased, the effects of PEO on DOD drop formation increase significantly, and the effects of concentration become important. These effects are explained by the fluid elasticity which increases with increasing in molecular weight and concentration. When the liquid jets out of the nozzle, the polymer chains are stretched, and thus depart from their ideal coiled state. As a result, an elastic stress develops in the liquid column and resists capillarity-driven pinch off from the nozzle and is responsible for the decrease in drop speed and longer breakup time. DOD drop formation data were shown to correlate closely with effective relaxation time, proposed by Tirtaatmadja based on Rouse-Zimm theory. When driving voltage amplitude is 44.2 V, two important parameters (breakup time and primary drop speed) in DOD drop formation for solutions containing monodispersed PEO and aqueous solutions containing mixtures of monodispersed PEO were closely predicted by correlation equations involving effective relaxation time . A mixture rule was developed to calculate the relaxation time for mixtures of monodispersed PEO. However, for polydispersed PEO, effective relaxation time was based on viscous molecular weight since the molecular weight distributions of the polydispersed PEO were unknown. When breakup time was plotted versus effective relaxation time for 1000k g/mol PEO, the data did not lie on the same line as that for the 100k and 300k g/mol PEO. This is believed to be due to the molecular weight distributions of the polydispersed PEO. When more than one species are present, viscous average molecular weight does not adequately account for the long chain species making up the polymer sample. DOD drop formation dynamics is highly affected by the actuating waveform, including the driving voltage, waveform shape, and frequency. The effects of parameters (jetting frequency, voltage amplitude and the shape of waveform) characterizing the signal were investigated. The open time and first drop problem were also studied. Research in this dissertation gives a better understanding of DOD drop formation process of polymer solutions, which may lead to improvement of inkjet printing quality for a variety of industry inks and polymer micro scale deposition and patterning in large areas.

<p>Poly(vinyl alcohol) and polyethylene polymer systems werebuilt in order to study their transport properties (diffusion).First a verification of the AMBER force field was conducted fora poly(vinyl alcohol) system built from a chain with 145repeating units. NPT-molecular dynamics simulations attemperatures between 400 and 527 K were performed. The resultsof the simulations were compared withpressure-volume-temperature data, solubility parameter, X-rayscattering pattern and data for the characteristic ratio. Thefractional free volume distribution was computed and thediffusion characteristics of water in the polymer werestudied.</p><p>Further another poly(vinyl alcohol) system, with 600repeating units, was used to study oxygen diffusion in dry andwet poly(vinyl alcohol). In these systems the focus was toinvestigate the oxygen paths relative to the backbone and alsothe effect of water on the diffusion coefficients. Jump mapsand correlation function between the velocity of the oxygen wascalculated. The water has a huge impact on the oxygen diffusionand the preferred paths.</p><p>A larger molecule (limonene) was studied in a polyethylenematrix consisting of 6000 anisotropic united atoms. A 100 nslong trajectory was recorded and also shortertrajectories atdifferent temperatures, which gave the temperature dependenceof the diffusion coefficients. Correlation functions for thelimonene molecule shows that it rotates and tumbles when movingthru the matrix.</p><p>The main results from the molecular dynamics simulationsshowed that diffusion of larger molecules are possible and alsothat molecular dynamics simulations can predict plasticizationeffects.</p><p>A new fast experimental method for determining diffusioncoefficients with non iso thermal thermogravimetry weredeveloped. The advantage is that the experiments only takesminutes instead of days with a small effect on theaccuracy.</p>

<p>The sorption/desorption behaviour of n-hexane in high molarmass linear polyethylene (PE) and branched PEs with 0.39 and5.09 hexyl branches per 100 main chain C atoms andcrystallinities between 4 and 82% at 298 K has been studied.Crystal core contents determined by Raman spectroscopy werealways lower than those determined by density measurements. Then-hexane solubilities in the copolymers depended in anon-linear manner on the content of penetrable polymercomponent and were lower for homogeneous copolymers than forheterogeneous copolymers at the same contents of penetrablecomponent. The solubility of hexane in the linear PE sampleswas proportional to the volume fraction of the penetrablepolymer and the solubility was low in comparison with that ofthe branched PE of the same crystallinity. TheCohen-Turnbull-Fujita (CTF) free volume theory was capable ofdescribing the desorption process in the PEs studied. Theconcentration dependence of the thermodynamic diffusivitypredicted by the CTF free volume theory was confirmed by thedata obtained by the differential method, and the differencesbetween the results obtained by the integral and differentialmethods were within the margins of experimental error. Thedependence of the fractional free volume of the penetrablephases on the phase composition suggests that mass transporttakes place from the liquid-like component to the interfacialcomponent and that the penetrant molecules are trapped at theinterfacial sites. The linear PE samples showed a physicallyrealistic trend with a decrease in the geometrical impedancefactor (t) with decreasing degree of crystallinity, whereas theopposite trend was obtained for the copolymers. The decrease int with increasing crystallinity in the copolymers may beexplained by the presence of wide crystal lamellae in the lowcrystallinity samples.</p><p>A novel melt-extrusion method was used to createcircumferential chain orientation in pipes of crosslinked PE.The microstructure of the pipes was characterized usingdifferential scanning calorimetry (DSC), density measurements,X-ray diffraction, infrared dichroism and contractionmeasurements. The mechanical properties were assessed byuniaxial tensile tests. The maximum degree of circumferentialorientation was obtained at the inner wall of the orientedpipe. The oriented pipe material exhibited a 5-15% higherdegree of crystallinity and a greater crystal thickness thanconventionally crosslinked pipe. The circumferential and axialmoduli of the oriented, crosslinked pipe were greater than thecorresponding moduli of the non-oriented crosslinked pipe.</p><p>Blends of single-site materials of linear PE andethyl-branched PE were prepared using solution- and melt-mixingmethods. The thermal properties of the blends were studied byDSC and results obtained by the two mixing methods werecompared. Data obtained for heats of melting andcrystallization, melting and crystallization peak temperaturesand melting and crystallization temperature profiles wereessentially the same for the samples obtained by the two mixingmethods. The heat associated with the high temperature meltingpeak of the blend samples obtained by both preparation methodsafter crystallization at 398 K was higher than that of thelinear polyethylene included in the blends, suggesting that apart of the branched polyethylene crystallized at 398 K.</p><p><b>Key words:</b><i>n</i>-Hexane diffusion, polyethylene, free volume,solubility, sorption, desorption, mechanical properties,orientation, thermal properties, blend.</p>