Cette recherche est consacrée à l'étude des interactions entre les fillers et le ciment. Ces interactions peuvent avoir une origine physique et/ou chimique. L'utilisation d'un filler de référence, inerte chimiquement (une zircone), permet de séparer les deux effets. Nous montrons que les fillers (calcaire et zircon) de par leur activité chimique peuvent agir favorablement sur les propriétés mécaniques des pâtes pures et des mortiers. Ils ont un effet accélérateur et participent à la formation des espèces hydratées. Une partie importante de l'étude concerne l'interaction du filler calcaire avec le constituant principal du ciment, à savoir: le silicate tricalcique. L'activité chimique des fillers varie suivant leurs origines et les traitements qu'ils subissent. Le broyage peut être à l'origine de la création de défauts planaires, linéaires et ponctuels. Ceux-ci déterminent la réactivité du filler. Il existe une relation entre cette activité chimique et les propriétés mécaniques des pâtes pures. Cette corrélation nous permet de préconiser un test de sélection des fillers calcaires.

When two or more individual materials combine to form a new material with improved characteristics, a composite is created. The two major components in a thermoplastic composite are the polymer, such as polypropylene (PP), and the filler, such as minerals like calcium carbonate and talc, or agricultural crop by-products like wheat straw, soy hull and soy stems. The main advantages of using agricultural fillers (AgFillers) in polypropylene are cost reduction and modulus improvement, without drastically increasing the specific gravity of the composite. These properties can be further enhanced by subjecting the composite to the bulk orientation process, in which the polymer chains align to give superior strength to the material, while the presence of polar AgFillers contributes to a reduction in material density. The objective of this research was to systematically study the relationships between the components and properties of AgFiller-PP composites, and their contributions to property modifications. Three types of AgFillers, wheat straw (WS), soy hulls (SH) and soy stems (SS) were studied, along with two PP types, virgin PP (vPP) and recycled PP (rPP), and mixtures of the two PP types. Non-oriented composites with a composition ratio of 40 wt% AgFiller to 60 wt% PP were tested for their morphology, chemical, thermal, rheological and mechanical properties. Similar properties of oriented composites with 20 wt% wheat straw filler and 80 wt% PP were also examined. The type of AgFiller was found to play a significant role in determining the rheological and mechanical properties of non-oriented AgFiller-PP composites. Scanning electron microscopy (SEM) showed that AgFillers had the tendancy to align lengthwise when subjected to the extrusion process. Depending on the fiber alignment within the filler with respect to the lengthwise direction of the filler, each AgFiller contributed differently to the composites’ properties. Stem-based AgFillers like WS and SS had fiber alignment parallel to the lengthwise direction, and the composites created had higher viscosity and higher flexural modulus. On the other hand, shell-based AgFillers like SH had fiber alignment perpendicular to the filler’s length, and were found to have less contribution to viscosity increase. Fourier transform Infrared (FTIR) spectroscopy using attenuated total reflectance (ATR) technique showed that a skin layer of PP congregated on the surface of all the non-oriented AgFiller-PP composites, regardless of the AgFiller used. The main contribution of PP polymer type was to the rheological properties of non oriented AgFiller-PP composites. The presence of rPP also appeared to slightly improve the immiscibility between polar AgFillers and nonpolar PP polymer, according to SEM image analysis. The viscosity of the composites decreased linearly with increasing amount of rPP, because the rPP tested had significantly lower viscosity than the vPP chosen. No statistically significant conclusions could be drawn on the mechanical property changes due to large experimental variance that existed in the data. Bulk orientation of AgFiller-PP composites was shown to provide significant reduction in the material’s density as well as improvement in physical properties. Experimental results of oriented wheat straw-PP composites showed that wheat straw was highly comparable, perhaps even more superior, to wood fibers as filler for oriented PP composites. The ability to produce oriented wheat straw-PP composites using the same technology and conditions as producing oriented wood-plastic composites affirmed the feasibility for commercialization of oriented wheat straw-PP composites, and by means contributing to setting a milestone in the scientific research of AgFiller-thermoplastic biocomposites.

When two or more individual materials combine to form a new material with improved characteristics, a composite is created. The two major components in a thermoplastic composite are the polymer, such as polypropylene (PP), and the filler, such as minerals like calcium carbonate and talc, or agricultural crop by-products like wheat straw, soy hull and soy stems. The main advantages of using agricultural fillers (AgFillers) in polypropylene are cost reduction and modulus improvement, without drastically increasing the specific gravity of the composite. These properties can be further enhanced by subjecting the composite to the bulk orientation process, in which the polymer chains align to give superior strength to the material, while the presence of polar AgFillers contributes to a reduction in material density. The objective of this research was to systematically study the relationships between the components and properties of AgFiller-PP composites, and their contributions to property modifications. Three types of AgFillers, wheat straw (WS), soy hulls (SH) and soy stems (SS) were studied, along with two PP types, virgin PP (vPP) and recycled PP (rPP), and mixtures of the two PP types. Non-oriented composites with a composition ratio of 40 wt% AgFiller to 60 wt% PP were tested for their morphology, chemical, thermal, rheological and mechanical properties. Similar properties of oriented composites with 20 wt% wheat straw filler and 80 wt% PP were also examined. The type of AgFiller was found to play a significant role in determining the rheological and mechanical properties of non-oriented AgFiller-PP composites. Scanning electron microscopy (SEM) showed that AgFillers had the tendancy to align lengthwise when subjected to the extrusion process. Depending on the fiber alignment within the filler with respect to the lengthwise direction of the filler, each AgFiller contributed differently to the composites’ properties. Stem-based AgFillers like WS and SS had fiber alignment parallel to the lengthwise direction, and the composites created had higher viscosity and higher flexural modulus. On the other hand, shell-based AgFillers like SH had fiber alignment perpendicular to the filler’s length, and were found to have less contribution to viscosity increase. Fourier transform Infrared (FTIR) spectroscopy using attenuated total reflectance (ATR) technique showed that a skin layer of PP congregated on the surface of all the non-oriented AgFiller-PP composites, regardless of the AgFiller used. The main contribution of PP polymer type was to the rheological properties of non oriented AgFiller-PP composites. The presence of rPP also appeared to slightly improve the immiscibility between polar AgFillers and nonpolar PP polymer, according to SEM image analysis. The viscosity of the composites decreased linearly with increasing amount of rPP, because the rPP tested had significantly lower viscosity than the vPP chosen. No statistically significant conclusions could be drawn on the mechanical property changes due to large experimental variance that existed in the data. Bulk orientation of AgFiller-PP composites was shown to provide significant reduction in the material’s density as well as improvement in physical properties. Experimental results of oriented wheat straw-PP composites showed that wheat straw was highly comparable, perhaps even more superior, to wood fibers as filler for oriented PP composites. The ability to produce oriented wheat straw-PP composites using the same technology and conditions as producing oriented wood-plastic composites affirmed the feasibility for commercialization of oriented wheat straw-PP composites, and by means contributing to setting a milestone in the scientific research of AgFiller-thermoplastic biocomposites.

A unique approach for lightweight multifunctional composites was developed using Fe3O4 nanoparticles and polypyrrole-coated Fe3O4 particles as fillers. Fe3O4 particles are a good candidate for filler in a multifunctional composite system because they can reinforce mechanical properties of a polymer matrix and impart magnetic properties into a composite. Polypyrrole coating on Fe3O4 particles was utilized to incorporate electrical conductivity to the properties of composites. The effects of filler size and filler content were studied on both the mechanical and electromagnetic properties. Fe3O4 nanoparticles improved fracture toughness, but they compromised strength and modulus. Polypyrrole-coated Fe3O4 has potential for multifunctional material applications because the coating allows for concurrent increase in magnetic permeability and electrical conductivity in a composite. The polypyrrole coating also improved the strength of the composite. Fe3O4 nanoparticles were a major part of this work from their synthesis to their application in composites. The surface effect on magnetic properties was analyzed for Fe3O4 nanoparticles, resulting in a more accurate calculation of the magnetically dead layer thickness than previously reported. The results from this work contributed to further understanding of synthesis and characterization of magnetic nanoparticles, fabrication and characterization of nanocomposites, and design and development of lightweight multifunctional materials. Although the properties of the fabricated composites require further improvement, the methodology and approach provide a basis for future work in development of lightweight multifunctional composites.

In this study calcium carbonate (CaCO3) particles are surface modified by using plasma polymerized natural gas and effects of surface modification of CaCO3 filler on mechanical properties of CaCO3-PP composites are investigated. Different combination of plasma factors / RF power, natural gas flow rate, and plasma discharge durations, are investigated. Mechanical properties such as tensile strength and Young&rsquo / s Modulus are measured by tensile testing machine. Storage modulus and loss modulus measurements are done by DMA. Some information about structures generated by natural gas plasma surface modification is obtained by FTIR tests. The tensile fracture surfaces of prepared composites are investigated by using SEM micrographs. It is concluded that, despite some enhancement obtained in the moduli / the technique of natural gas plasma surface modification of CaCO3 particles did not introduce significant improvement in mechanical properties of composite as expected. This result may partially be attributed to selected plasma parameters (i.e., flow rate, RF power, and discharge duration).

There are many different types of fillers used for bitumen modification such as / silica, limestone, basalt, mica, oyster shells. Filler gives rigidity, stiffness or hardness, regulates thermal expansion and shrinkage, improves heat resistance, and modifies rheological properties of bituminous composites. The main objective of this study was to determine the effect of filler type and ratio on mechanical, thermal properties and morphologies of bitumen based composites. It was also aimed to improve the heat resistivity of the bituminous composite to obtain a material with good mechanical and heat isolation properties. Bituminous composites were prepared by using Brabender Plasti-Corder, PLV 151. Mixing was made at 180 &ordm / C with 60 rpm for 15 minutes. Two grades of bitumen as 20/30 and 50/70 penetrations were used. CaCO3, CaO, mica, baryte, kieselguhr and silaned kieselguhr were used as fillers in this study. Ethylene vinyl acetate copolymer, styrene&amp / #8211 / butadiene rubber, and styrene&amp / #8211 / butadiene&amp / #8211 / styrene block copolymer were used as polymers. According to the test results, using mica at low percentages had the effect of decreasing the viscosity of the bitumen due to its flow alignment property. Baryte gave high heat capacity and low heat conductivity to bituminous material. EVA containing samples showed the best combination on mechanical properties. The silanation process decreased the pore sizes as observed in mercury porosimetry experiments. A decreased amount of bitumen impregnation was obtained by the silanation process, clearly observed in SEM micrographs.

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.

This dissertation examines the processing of sentences involving long-distance linguistic dependencies, or sentences containing elements that must be linked across intervening words and phrases. Specifically, both behavioral (self-paced reading and eye tracking) and neurophysiological (electroencephalography) methods were used (a) to evaluate the relative importance of backward- and forward-looking dependency satisfaction processes in the comprehension of sentences involving wh-dependencies and (b) to determine the extent to which common neurocognitive mechanisms are involved the processing of wh- and anaphoric dependencies. With respect to the first issue, both behavioral andneurophysiological results indicated a core role for forward-looking, expectancy-based processes in the comprehension of wh-dependency sentences. Regarding the latter issue, despite considerable overlap in the reading patterns associated with wh-dependencies and (at least some types of) anaphora, the neurophysiological responses related to these dependency types indicated that their processing draws on distinct neurocognitive mechanisms.

The development of a fuel filler pipe is based solely on experience and physical experiment. The challenge lies in designing the pipe to fulfill the customer needs. In other words designing the pipe such as the fuel flow does not splash back on the fuel dispenser causing a premature shut off. To improve this “trial-and-error” based development a computational fluid dynamics (CFD) model of the refueling process is investigated. In this thesis a CFD model has been developed that can predict the fuel flow in the filler pipe. Worst case scenario of the refueling process is during the first second when the tank is partially filled. The most critical fluid is diesel due to the commercially high volume flow of 55 l/min. Due to limitations of computational resources the simulations are focused on the first second of the refueling process. The challenge in this project is creating a CFD model that is time efficient, thus require the least amount of computational resources necessary to provide useful information. A multiphase model is required to simulate the refueling process. In this project the implicit volume of fluid (VOF) has been used which has previously proven to be a suitable choice for refueling simulations. The project is divided into two parts. Part one starts with experiments and simulations of a simplified fuel system with water as acting liquid with a Reynolds number of 90 000. A short comparison between three different turbulence models has been investigated (LES, DES and URANS) where the most promising turbulence model is URANS, specifically the SST k-ω model. A sensitivity analysis was performed on the chosen turbulence model. Between the chosen mesh and the densest mesh the difference of streamwise velocity in the boundary layer was 2.6 %. The chosen mesh with 1.9 M cells and a time step of 1e-4 s was found to be the best correlating model with respect to the experiments. In part two a real fuel filling system was investigated both with experiments and simulations with the same computational model as the chosen one from part one. The change of fluid and geometry resulted in a lower Reynolds number of 12 000. Two different versions of the fuel system was investigated; with a bypass pipe and without a bypass pipe. Because of a larger volumetric region the resulting mesh had 3.7 M cells. The finished model takes about 230 h on a local workstation with 11 cores. On a cluster with 200 cores the same simulation takes 30 h. The resulting model suffered from interpolation errors at the inlet which resulted in a volume flow of 50 l/min as opposed to 55 l/min in the experiments. Despite the difference the model could capture the key flow characteristics. With the developed model a new filler pipe can be easily implemented and provide results in shorter time than a prototype filler pipe can be ordered. This will increase the chances of ordering one single prototype that fulfills all requirements. While the simulation model cannot completely replace verification by experiments it provides information that transforms the development of the filler pipe to knowledge based development.

Thesis (M.S.)--Oregon State University, 2011. / Printout. Includes bibliographical references (leaves 85-91). Also available on the World Wide Web.