As the demand of oil and gas is increasing, using the existing reservoirs more efficiently as well as searching for new reservoirs is mandatory. Most undiscovered reservoirs are in deep or ultra-deep offshore locations, where drilling to such targets are very difficult with the available fluid circulation technology, since there exists a significant frictional pressure loss due to extreme long wellbores. In order to reduce the frictional pressure losses inside the drillstring, frictional drag reducers are used. Frictional drag reducers are mostly high molecular weight linear polymer molecules and can be used with water or hydrocarbon based solvents. The system used in this study is Baroid EZ-Mud water solutions. Baroid EZ-Mud is a liquid polymer emulsion containing partially hydrolyzed polyacrylamide / polyacrylate (PHPA) co-polymer. This study aims to observe the performance of EZ-Mud as a frictional drag reducer. For this purpose, a flow loop that consisted of a circular pipe where the frictional pressure losses can be observed under various flow rates and concentrations is developed. Pipe flow experiments were performed using water-based mud generated using different concentrations of Baroid EZ-Mud at different flow rates. Differential pressure values were recorded for each run. Rheological properties of each mud sample were determined using Fann (Couette) viscometer in order to determine the theoretical frictional pressure losses. Theoretical and measured frictional pressure losses were compared. Results showed that, as the concentration of EZ-Mud was increased, considerable frictional drag reduction as high as 60% was observed. Based on the experimental data obtained from the flow loop using EZ-Mud with different concentrations, a friction factor correlation as a function of Reynolds Number and EZ-Mud concentration is developed. The proposed correlation performance was also compared with the existing correlations from the literature. It has been observed that, frictional pressure losses using the developed friction factor could be estimated within an error range of maximum 15 %, whereas, the existing models could not predict frictional pressure losses as accurate as the proposed model.

The aim of this study was to improve the mechanical properties of a recycled grade polypropylene. Polymer blends and nanocomposites were prepared by melt compounding method in a twin screw extruder. Cloisite&reg / 15A, Cloisite&reg / 25A and Cloisite&reg / 30B were used as organoclays, and ethylene-methyl acrylate-glycidyl methacrylate (E-MA-GMA) and maleic anhydride grafted polypropylene (PP-MAH) were used as compatibilizers. The effects of additive concentrations, types of organoclays and compatibilizers, processing conditions, and the compatibilizer to organoclay ratio on the morphology and mechanical, thermal and flow properties were investigated. Organoclay loading over 2 wt% prevented the intercalation mechanism and material properties, even in the presence of compatibilizer, as a consequence of large clay agglomerate formation. E-MA-GMA compatibilizer improved the intercalation ability of the polymer / however a substantial increase in mechanical properties was not obtained. PP-MAH is found to be a better compatibilizer. Processing conditions significantly affected both mechanical properties and morphology. When the processing temperature was decreased and screw speed was increased simultaneously, tensile and impact properties were improved owing to enhanced shear and dispersive forces. TEM analysis revealed that intercalated and delaminated structures were formed with the addition of PP-MAH compatibilizer. In addition to that, as the ratio of PP-MAH to organoclay was increased, more effective dispersion of organoclay was observed and hence resultant improvements in both tensile and impact properties were greater at compatibilizer to organoclay ratio of three. Cloisite&reg / 15A exhibited the highest improvements in mechanical properties, although the degree of organoclay dispersion was better for Cloisite&reg / 25A and particularly for Cloisite&reg / 30B. Melt flow index values were lower compared to pure recycled polypropylene in the presence of organoclay and compatibilizers. DSC analysis indicated no significant change in the melting behavior of the matrix materials.

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.

Micron size non-treated / silane coupling agent (SCA) treated serpentine filled acrylonitrile-butadiene-styrene (ABS) composite preparation and characterization of composites in terms of mechanical, thermal, flow properties and morphology were studied in this work. First step of the study was the size reduction of the as collected serpentine mineral. Secondly, three types of silane coupling agent treatments were applied to serpentine which were gamma-methacryloxypropyltrimethoxysilane (A-174), beta-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane (A-186) and gamma-mercapto-propyltrimethoxysilane (A-189). Non-treated and three different types of SCA treated serpentine minerals were melt mixed with ABS. Non-treated serpentine filled ABS composites had the serpentine weight fractions of 2%, 5%, 10% and 20%. On the other hand, SCA treated ones had serpentine weight fractions of 2%, 5% and 10%. Morphological analysis showed that SCA treatment was partly effective in interface interaction enhancement and A-186 gave the best results according to micrographs. There wasn&amp / #8217 / t any critical mechanical property loss up to 20% serpentine addition. Tensile tests revealed that SCA treatment increased the yield strength values of composites compared to non-treated serpentine filled composites. In accordance with morphological study, best result was obtained from 5% A-186 treated serpentine filled ABS as 12.9% improvement in yield strength value. Percent elongation at break values were increased with filler addition and greatest increase was observed in A-189 treated samples. Serpentine addition had no net effect on Young&amp / #8217 / s Modulus values. According to the impact testing results, A-189 treated samples had improved toughness compared to non-treated samples in accordance with elongation at break values. However increasing filler content resulted with decrease in impact strength values. DSC analysis showed that glass transion temperatures, especially for SCA treated samples, were decreased compared to neat ABS with filler addition. This result suggests that SCA may had the plasticizing effect on the composite. Flow properties of composites were not different from neat ABS up to 2% addition, when the filler concentration was further increased melt flow index values were dramatically decreased.

Polystyrene, PS, is a preferable polymer in industry, but, its brittle characteristic restricts its utilization. The aim of this study is to improve the impact strength of PS by the help of elastomeric materials SEBS-g-MA and E-BA-GMA. In order to prevent the reduction in the tensile strength of the materials, three different types of organic montmorillonites, MMT, (Cloisite&reg / 30B, 25A and 15A) were used as fillers. Nanocomposite preparation was performed in a co-rotating twin screw extruder. Initially elastomer and organoclay contents were kept at 5wt% and 1-2wt% respectively. Well dispersed silicate layers were obtained for the nanocomposite containing SEBS-g-MA and Cloisite&reg / 25A owing to the high viscosity of SEBS-g-MA and the solubility of polystyrene end block of SEBS with PS matrix. Owing to higher hydrophobicity of Cloisite&reg / 15A a better dispersion was expected compared to Cloisite&reg / 25A, but, it was concluded that two long aliphatic tails of Cloisite&reg / 15A limited the access of polymer chains to the clay surface. The desired impact strength values could not be achieved by using 5wt% elastomeric materials / therefore, it was decided to increase the SEBS-g-MA content up to 15, 20, 30 and 40wt%. With increasing elastomer content, increasing average elastomer domain size was obtained. Also, it was observed that with the addition of organoclay, the elastomeric domain size increases since the clay particles reside in the elastomer phase and at the interphase between elastomer and PS. The mechanical test results showed that the nanocomposites containing 15 and 20wt% SEBS-g-MA have the optimum average domain size that results in better impact strength values without deteriorating tensile properties.

Although, several researches on synthesis and characterization of benzoxazines and polybenzoxazines have appeared in the literature, detailed studies on thermal characterization are still limited. In this study, polymerization and thermal degradation mechanisms of benzoxazines were investigated via direct pyrolysis mass spectrometry. Benzoxazine monomers prepared by reactions of phenol or bisphenol- A with aniline or methyl amine were analyzed to investigate the effects of the structures of phenyl and amine groups on both polymerization and thermal degradation behaviours. It has been proposed in the literature that polymerization of benzoxazines occurs by ring opening polymerization of oxazine ring / cleavage of O-CH2 bond of the oxazine ring and attack of n-CH2 group to phenol or bisphenol-A ring. However, the direct pyrolysis mass spectrometry analyses of polymerization and thermal degradation of benzoxazines pointed out that after the cleavage of O-CH2 bond of the oxazine ring, polymerization proceeded through opposing pathways. Strong evidences confirming coupling of (CH3)NCH2 or (C6H5)NCH2 groups yielding dimers involving diamine linkages were detected. Polymerization of the dimer by the reactions with the corresponding monomers was proposed. In case of benzoxazines based on bisphenol-A, the results indicated polymerization of the dimer ii by coupling of both of the oxazine rings. On the other hand, polymerization of the dimer through the ethylene units (vinyl polymerization) in case of benzoxazine monomer based on phenol and methyl amine was also noted. For polybenzoxazines based on aniline another polymerization pathway involved attack of radicals generated by cleavage of the oxazine ring to aniline ring. Multi-step thermal decomposition was observed for all the polybenzoxazines under investigation confirming the presence of units with different structures and stabilities.

This thesis addresses the application of xanthan/borate gel for lost circulation treatment. Steady shear viscometry method was applied in which the gel system was under constant shear rate while apparent viscosity was being recorded. The apparent viscosity was constant up to initial gelation time in which viscosity started to build up. Four parameters: initial and final gelation times as well as initial and final viscosities are defined and a correlation is derived between those parameters and four variables: polymer blended with crosslinker, pH-controller, and magnesium chloride concentration as well as temperature. These correlations can help the drilling industry to manage the lost circulation treatment job in a way to have enough time and pressure to pump the fluid and to optimize the time and quality required for final gel. The effects of those variables besides mixing time and shear history on gelation were also investigated. Temperature and pH-controller shortens initiation of gelation. Poly-cross shifts viscosity upward. Retarder postpones the final gelation time. Shear history does not affect initial gelation time and increase of mixing time reduces initial gelation time. This thesis also investigates the rheological model behavior of this gel system before initial gelation time which is the time allowed for pumping the fluid. Shear stress was measured at 0.1,1,50, and 450 rpm besides the conventional readings. Then residual mean squares for six common rheological models were obtained. Sisko was found to be the best fitting model based on this statistical approach. Moreover a modified Bingham-plastic and low shear yield point model are suggested.

In this study, degradation of ethylene propylene diene terpolymer (EPDM) via gamma radiation and possible use of EPDM in radioactive waste management were investigated. In estimation of radiation stability and possible use of EPDM in radioactive waste management, dose rate (both high and low), irradiation environment (in water and in air), additives (carbon black, zinc oxide, plasticizer) used in formulation, peroxide type (either aliphatic or aromatic) and content were parameters which were analyzed. Three EPDM samples having different peroxides were irradiated in water and in air with two different dose rates (993 Gy/h, 54 Gy/h) to 2163 kGy (for high dose rate) and 1178 kGy (for low dose rate). Irradiation periods for low dose rate were 2.5 years (last sample) which have not been observed in literature. Characterization of irradiated EPDM samples were done by mechanical (tensile, hardness, compression), dynamic mechanical (DMA), thermal (TGA-FTIR) and morphological (ATR-FTIR, XRD, SEM) tests. High dose rate irradiations were done in predicting how far EPDM resist to radiation and which dose rate emitted waste can be immobilized and stored in EPDM for 300 years. Low dose rate irradiations were carried out in determining morphological changes in structure, thermal stability, oxygen effect and types of reactions (crosslinking, chain scisson) which were dominant in irradiated samples. According to the test results, improvement in thermal properties and decrease in elasticity on EPDM via radiation were recorded from thermal and mechanical tests respectively. Moreover, structural changes were monitored from ATR-FTIR, SEM and XRD analysis. Mechanical tests showed that irradiated EPDM samples, which were differentiated with respect to peroxide type (aliphatic, aromatic), could resist up to total absorbed doses of 3750 kGy and 3955 kGy respectively. Up to 1178 kGy in low dose irradiation, there were not much structural changes, which were observed in ATR-FTIR analysis, in EPDM chain. It was concluded that EPDM rubber used in this study were radiation stable polymer so that they could possibly be used in conditioning of radioactive waste.

In this thesis, there were four purposes. The first one was to investigate effects of nanoclays (NC) on the flammability behavior of polystyrene (PS). The second purpose was to investigate contribution of nanoclays to the flame retardancy performance of conventional phosphorus based flame retardant / triphenyl phosphate (TPP) and its synergist melamine cyanurate (MCA). For the third purpose contribution of nanoclays to the flame retardancy performance of another conventional halogenated flame retardant / brominated epoxy polymer (BE) and its synergist antimony trioxide (AO) was investigated. As the fourth purpose, effects of another nanoadditive / carbon nanotubes (CNTs) on the flammability behavior of PS with and without BE-AO flame retardant system was investigated. Materials were prepared via &ldquo / solution mixing&rdquo / method, while test specimens were shaped by compression and injection molding. Flammability behaviors were investigated by Mass Loss Cone Calorimeter (MLC), Limiting Oxygen Index (LOI) and UL-94 Vertical Burning tests. Other characterization techniques required in this thesis were / X-ray diffraction analyses, scanning and transmission electron microscopy, thermogravimetric analyses and tensile tests. It was revealed that use of nanoclays improved flame retardancy of PS significantly, mainly with &ldquo / condensed phase&rdquo / mechanism via formation of strong char barrier layers inhibiting mass and heat transfer. When nanoclays were used together with conventional flame retardant systems TPP-MCA and BE-AO, flame retardancy parameters improved further, this time due to the &ldquo / synergistic action&rdquo / of &ldquo / condensed phase mechanism&rdquo / of nanoclays and &ldquo / gas phase mechanism&rdquo / of the conventional systems. Use of carbon nanotubes also resulted in improvements in the flame retardancy of PS. However, &ldquo / condensed phase mechanism&rdquo / of CNTs were not as effective as the NCs, which might be due to the lower performance of 1D geometry (CNTs) compared to higher efficiency of 2D geometry (NC) in barrier formation. As an additional purpose, effects of mixing methods in the production of PS-Nanoclay composites were also investigated. It was seen that compared to &ldquo / solution mixing&rdquo / use of &ldquo / in-situ polymerization&rdquo / resulted in poorer flame retardancy parameters that might basically be due to residual monomers or oligomers left during polymerization.

This study was conducted to investigate the effects of component concentrations and addition order of the components, on the final properties of ternary nanocomposites composed of poly(ethylene terephthalate), organoclay, and an ethylene/methyl acrylate/glycidyl methacrylate (E-MA-GMA) terpolymer acting as an impact modifier for PET. In this context, first, the optimum amount of the impact modifier was determined by melt compounding binary PET-terpolymer blends in a corotating twin-screw extruder. The amount of the impact modifier (5 wt. %) resulting in the highest Young&rsquo / s modulus and reasonable elongation at break was selected owing to its balanced mechanical properties. Thereafter, by using 5 wt. % terpolymer content, the effects of organically modified clay concentration and addition order of the components on ternary nanocomposites were systematically investigated. Mechanical testing revealed that different addition orders of the materials significantly affected mechanical properties. Among the investigated addition orders, the best sequence of component addition (PI-C) was the one in which poly(ethylene terephthalate) was first compounded with E-MA-GMA. Later, this mixture was compounded with the organoclay in the subsequent run. Young&#039 / s modulus of not extruded pure PET increased by 67% in samples with 5 wt. % E-MA-GMA plus 5 wt. % clay loading. The highest percent elongation at break was obtained as 300%, for the addition order of PI-C, with 1 wt. % clay content, which is nearly 50 fold higher than that obtained for pure PET. In X-ray diffraction analysis, extensive layer separation associated with delamination of the original clay structure occurred in PI-C and CI-P sequences with both 1 and 3 wt. % clay contents. X-ray diffraction patterns showed that, at these conditions exfoliated structures resulted as indicated by the disappearence of any peaks due to the diffraction within the consecutive clay layers.