Thesis (Ph. D.)--University of Alabama at Birmingham, 2006. / Additional advisors: James S. Davidson, Derrick R. Dean, Gregg M. Janowski, Mark L. Weaver. Description based on contents viewed Jan. 24, 2007; title from title screen. Includes bibliographical references (p. 235-246).

Within the past several years, researchers have detected the presence of a third “phase” between the bulk fiber phase and bulk matrix phase in a polymeric matrix composite. This finite-thickness region — termed the interphase — possesses mechanical, physical, and chemical properties that are distinct from the fiber and matrix constituents. Thus, the interphase embodies the characteristics of the fiber/matrix bond, including the strength and stiffness of the bond. In essence, the interphase represents the composite system, since it defines the level of synergistic interaction that occurs between the load-carrying fibers and the binding matrix material. Recent interest in the interphase has spawned international conferences and a technical journal devoted to its study. Despite this spate of research, some very fundamental questions about the interphase have remained unanswered. One such question is: “What is best for the performance of a composite, a strong or weak or intermediate-strength interphase?” It is surprising that this question is even asked, since, until recently, it had been assumed that the stronger the fiber/matrix bond, the better the composite behavior. It is now known that this adage is far from true. Two formidable challenges await those who wish to correlate the strength of the interphase to the mechanical performance of polymeric matrix composite materials. First, one seeks to systematically alter the interphase in order to exploit this variable. In this study, fourteen material systems representing permutations of four carbon fibers, three matrix systems, percentages of fiber surface treatment, and three sizing conditions have been examined. Secondly, one needs to quantitatively characterize the properties of the resultant interphase in order to correlate the bond condition to the composite’s mechanical behavior. This investigation utilizes two techniques, the Continuous Ball Indentation Test and transverse flexure testing, as a means of interrogating the strength of the interphase. The influence of the interphase on the tensile and compressive strength and modulus of crossplied laminates possessing a center hole is investigated. Unnotched angle-ply ([±45]_ns) laminates are also tested in order to assess the role of the interphase in the strength of a “matrix-dominated” laminate. Fully-reversed (R =-1), axial fatigue of notched cross-plied laminates from each of the fourteen material systems 1s performed. During fatigue testing several data are monitored, including cycles to failure, dynamic modulus, and notch temperature. The tension-tension (R= 0.1) fatigue response of the unnotched angle-ply laminates is also studied. Results from X-ray radiography of fatigue-damaged specimens help to explain the relationship between the interphase and the initiation and propagation of life-critical damage mechanisms. Having observed the formative role played by the interphase in the performance of these laminates, an attempt is made to introduce variables representing the interphase into micromechanical models of composite behavior. / Ph. D.

Surface free energy of a polymer is of great importance in adhesive studies. Acid/base specific interactions play pertinent roles in adhesive bond performance and polymer-polymer miscibility. In this study, the correlation between the surface characteristics of two polymers and their adhesive bond behavior as well as the compatibility of their blend systems are investigated through both the surface characterizations and bulk examinations. Inverse Gas Chromatography (IGC) is employed to determine the surface free energies, the dispersive component and acid/base specific interactions, of polyethylene terephthalate (PET), cellulose acetate (CA) and their blend. Dynamic Contact Angle (DCA) measurements are performed to obtain the surface free energies of PET and CA so that they can be compared to that from IGC. Moreover, the DCA data are used to calculate their spreading coefficients and the adhesive bond behavior between PET and CA is predicted as well. The bulk examinations on specific interactions and the miscibility of the PET/CA , PBT/CA blends are completed through Fourior Transform Infrared-Diffuse Reflectance Spectroscopy (FTIR-DRIFT), Differential Scanning Calorimeter (DSC) and Dynamic Mechanical Analyzer (DMA). Scanning Electron Microscopy (SEM) micrographs of these blends are taken to examine their morphologies. From IGC, it is deterrnined that the surfaces of PET and CA are predominantly basic. The spreading coefficients calculated from DCA data indicate the poor adhesive bond between PET and CA. The bulk examinations reveal that both PET/CA and PBT/CA blends are immiscible systems. / Master of Science

published_or_final_version / Chemistry / Master / Master of Philosophy

Submitted in fulfillment of the requirements for the degree of Doctor of Engineering: Mechanical Engineering, Durban University of Technology, Durban, South Africa, 2015. / Vacuum Infusion (VI) and Resin Transfer Moulding (RTM) are liquid composite moulding processes used in the manufacture of components from composite materials. The composite material in this case consists of a resin matrix combined with fibre reinforcement. In both moulding processes, a dry reinforcement preform is placed in the mould cavity and a liquid resin is introduced, driven by a pressure differential. Two rigid surfaces are used in RTM to create a fixed mould cavity. In contrast VI implements only one rigid surface and a flexible membrane or vacuum bag to form a non rigid cavity. The flexible cavity in VI influences and differentiates resin flow behaviour from that of RTM. Modelling resin flow enables the velocity, pressure and flow direction to be predicted. Resin flow in the RTM process is understood and modelled using Darcy’s law. However, flow in the VI process is not accurately modelled due to the added complexity introduced as a result of the flexible cavity. In the present work a novel approach was developed to investigate fluid flow in both processes. A unique experimental setup and testing procedure allowed for the direct comparison of fluid flow in RTM and VI. Identical flow parameters, conditions and preform construction were used in the assessment. The comparison isolated the effect of preform thickness variation as a differentiating factor influencing flow. From the experimentation, material behaviour was characterised and used to evaluate flow models for RTM and in particular VI. The model solutions were compared back to corresponding experiments. The pressure distribution behind the flow front, fill time and thickness behaviours were assessed. The pressure distribution / profiles behind the flow front of both VI and RTM were noted to be scalable with flow front progression. The profiles were curved in the VI experiments and linear in the RTM case. All VI models evaluated including the non accumulation based model accurately predicted the pressure distribution and consequently thickness variations in the VI tests. Fill times of the VI experiments were longer than that of the equivalent RTM tests. This behaviour is in contrast to previously interpreted fill time behaviour for the VI process based on VI models. It was also noted that the VI fill times were not only proportional to the square of the fill length, as in the RTM case, but also proportional to the square of the mass present. In addition, no significant accumulation was noted in the VI experiments. / D

by De-Dong Wu. / Publication date from spine. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1995. / Includes bibliographical references (leaves 175-184). / Acknowledgment --- p.i / Abstract --- p.ii / Table of Contents --- p.iii / List of Tables --- p.iv / List of Figures --- p.v / Chapter 1. --- Introduction --- p.1 / Chapter 1.1. --- The Chemistry of Coordination Polymers --- p.1 / Chapter 1.2. --- Generation of Coordination Polymeric Structures --- p.2 / Chapter 1.3. --- Research Strategy --- p.7 / Chapter 2. --- Description of Crystal Structures --- p.15 / Chapter 2.1. --- The Double Betaine Compounds --- p.15 / Chapter 2.2. --- Complexes of Silver(I) --- p.39 / Chapter 2.3. --- Complexes of Cadmium(II) --- p.60 / Chapter 2.4. --- Complexes of Mercury(II) --- p.89 / Chapter 2.5. --- Complexes of Copper(II) and Sodium(I) --- p.113 / Chapter 3. --- Summary and Discussion --- p.127 / Chapter 3.1. --- Generation of Coordination Polymeric Structures --- p.127 / Chapter 3.2. --- Coordination Modes of Double Betaines --- p.132 / Chapter 3.3. --- Conformation of the Double Betaines --- p.135 / Chapter 3.4. --- Synthesis of Betaine Compounds --- p.139 / Chapter 4. --- Experimental --- p.150 / Chapter 4.1. --- Preparation --- p.150 / Chapter 4.2. --- Physical Measurements --- p.164 / Chapter 4.3. --- Crystallography --- p.164 / Chapter 5. --- References --- p.175 / Appendix --- p.185 / Chapter 1. --- Atomic coordinates and equivalent isotropic thermal parameters --- p.185 / Chapter 2. --- Anisotropic thermal parameters --- p.196 / Chapter 3. --- H-atom coordinates and isotropic thermal parameters --- p.203

Zhou, Wenjia = 聚苯乙烯/銀聚合物納米棒陣列的合成、表征與生長的研究 / 周文佳. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 69-73). / Text in English; abstracts in English and Chinese. / Zhou, Wenjia = Ju ben yi xi / yin ju he wu na mi bang zhen lie de he cheng, biao zheng yu sheng zhang de yan jiu / Zhou Wenjia. / Chapter I. --- Abstract / Chapter IV. --- Acknowledgement / Chapter V. --- Contents / Chapter 1 --- Introduction / Chapter 1.1 --- Motivations / Chapter 1.2 --- Overview of the thesis / Chapter 2 --- Instruments / Chapter 2.1 --- Introduction to electron microscopes / Chapter 2.2 --- Scanning electron microscope / Chapter 2.2.1 --- Introduction to SEM working principle / Chapter 2.2.2 --- Electron specimen interactions and their applications in SEM / Chapter 2.2.3 --- Specific SEM conditions in the experiments / Chapter 2.3 --- Transmission electron microscope / Chapter 2.3.1 --- Introduction to TEM working principle / Chapter 2.3.2 --- Imaging mode and diffraction mode in TEM / Chapter 2.3.3 --- X-ray microanalysis with TEM / Chapter 2.3.4 --- Specific TEM conditions in the experiments / Chapter 3 --- Anodic aluminum oxide templates with different parameters / Chapter 3.1 --- Introduction to self-ordered anodic aluminum oxide / Chapter 3.1.1 --- Electrochemistry of anodic alumina / Chapter 3.1.2 --- Pore growth mechanism / Chapter 3.1.3 --- Self-ordered alumina by two-step anodization / Chapter 3.1.4 --- Other advanced methods for fabrication of monodomain AAO / Chapter 3.1.5 --- Applications of AAO templates in nanomaterials fabrication / Chapter 3.2 --- Preparation procedures of porous AAO templates we used / Chapter 3.2.1 --- Experimental setup / Chapter 3.2.2 --- General preparation procedures of AAO thin film on Al / Chapter 3.3 --- Experimental data of AAO templates with different parameters / Chapter 3.3.1 --- Different interpore distances / Chapter 3.3.2 --- Different pore depths and pore sizes / Chapter 3.3.3 --- Calibration of AAO templates pore depths and pore sizes at different anodic potentials / Chapter 4 --- Preparation of free standing polystyrene nanorods arrays with different parameters / Chapter 4.1 --- General preparation procedures of free standing polymer nanorods arrays / Chapter 4.2 --- Different rods intervals and diameters / Chapter 4.3 --- Limitations to the rods lengths control / Chapter 4.4 --- Discussion on the polymer properties for the successful preparation of free standing polymer rods arrays / Chapter 5 --- Thermal reduction method to embed Ag nanoparticles inside the polymer rods / Chapter 5.1 --- General preparation procedures of PS/Ag nanorods arrays / Chapter 5.2 --- Analysis method and procedure of Ag nanoparticles inside PS rods / Chapter 5.3 --- Typical TEM images of the three series samples / Chapter 5.4 --- Data analysis of Ag nanoparticles inside PS rods / Chapter 5.5 --- Discussion on Ag particles growth process / Chapter 5.6 --- Conclusion and suggestions for improvement / Chapter 6 --- Conclusion / Reference / Appendix

No description available.

Fiber reinforced polymeric (FRP) composites are beginning to find applications in constructing infrastructures such as bridges, railroads, etc. Composites may potentially be more durable replacements for steel and concrete, but their experience in these applications is minimal. Also, composite decks are susceptible to change in environmental conditions. Thus, the study of the behavior of composite material in elevated environmental conditions is necessary. This thesis is aimed at development and validation of Finite element methods used to analyze Fiber reinforced polymeric composite beam under moisture and elevated temperature change. The response of the composite beam subjected to various loads is analyzed under dry and moist conditions. It is assumed that only the matrix properties are adversely affected. The mechanical properties such as stiffness, strength, etc are degraded due to the combined effect of moisture and temperature change. The laminate properties are calculated using the rule of mixtures. A parametric study is carried out by varying the fiber volume fraction and by changing the fiber orientations and ply lay-ups in the laminate. From results it can be observed that the static and dynamic deflections increase due to the presence of moisture and increased temperature. The behavior of the beam is also influenced by the ply orientations and fiber volume fraction. Thus, for composite materials to reach their full potential in structural applications, it becomes quite imperative to consider factors such as moisture content, temperature, ply orientations and fiber volume during design and analysis. / Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering.

Single wall carbon nanotubes (SWNT) have been extensively studied over the last decade due to their excellent comprehensive properties for a variety of applications. This study is focused on the applications of SWNTs as reinforcement for polymer matrices. Due to van der Waal interactions, SWNTs form bundles of about 30 nm diameters. In order to take full advantage of the SWNT mechanical properties, SWNT must exfoliate or at least disperse in small diameter bundle size. Optical microscopy and SEM only give qualitative information of dispersion. Quantitative characterization through TEM or AFM can be time consuming in order to get statistical result. In this study, simple method is developed to quantitatively estimate the size of SWNT bundle in dispersion based on the geometry controlled electrical percolation behavior. The SWNTs can be dispersed /exfoliated via PVP wrapped SWNT aqueous dispersion assisted by surfactants such as sodium dodycel sulfate. PVA / SWNT composite films prepared through PVP wrapped SWNTs exhibit improved mechanical properties as well as the evidence of load transfer from the polymer matrix to the SWNT as monitored by the Raman spectroscopy. SWNT can also be well dispersed into PVA/DMSO/H2O solution. Gel spinning of PVA/SWNT composite fiber has been successfully carried out with improved mechanical properties. Functionalized tubes can be used to enhance SWNT dispersion and exfoliation. Oxidation in strong acids is one method used for functionalizing nanotubes. SWNTs have been functionalized in nitric acid. The structure and properties of films (buckypaper) processed from nitric acid functionalized tubes have been studied exhibiting high tensile strength and high electrical conductivity. Nitric acid treatment results in selective degradation of the small diameter tubes.