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Full-Text Articles in Engineering
An Experimental And Numerical Study Of The Film Casting Process, Kenneth Aniunoh
An Experimental And Numerical Study Of The Film Casting Process, Kenneth Aniunoh
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Film casting is a common industrial process used to produce polymeric films. During film casting, a polymer melt is extruded through a flat die before rapid cooling on a chill roll. The chill roll velocity is faster than the velocity at which the melt exits the die, thus the polymer melt is stretched and oriented in an extensional flow. The material properties and processing conditions have a significant impact on the process and the final thermal/mechanical properties of the film produced.
Optimization of industrial scale film casting processes is still greatly dependent on trial and error methods. Therefore, this work …
Effect Of Carbon Nanofibers On Microstructure And Properties Of Polymer Nanocomposites, Sungho Lee
Effect Of Carbon Nanofibers On Microstructure And Properties Of Polymer Nanocomposites, Sungho Lee
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Nano-modifiers are typically three orders of magnitude smaller in size than their micro-counterparts. At this scale, interactions between matrix molecules and the nano-modifiers can lead to novel physical and chemical properties of the resulting nanocomposites. Carbon nanofibers (CNFs) are a class of nano-modifiers that has received significant attention recently because they have superior electrical conductivity and mechanical properties with a high aspect ratio (length over diameter). Several recent research studies have focused on enhancing electrical and mechanical performance of composites in the presence of CNFs. However, the influence of CNFs on the structure of the polymer matrix is important in …
Biohydrogen Production By The Hyperthermophilic Bacterium Thermotoga Neapolitana, Xiaohui Yu
Biohydrogen Production By The Hyperthermophilic Bacterium Thermotoga Neapolitana, Xiaohui Yu
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ABSTRACT Thermotoga neapolitana can use different sources of carbon and nitrogen for growth and produces biological hydrogen. Sources of carbon (glucose, sucrose, xylose, xylan, cellulose, cellobiose, starch, corn starch, beet bulp pellet, and rice flour) and nitrogen (yeast extract, fish meal, cottonseed meal, canola meal, linseed meal, and soybean meal) were compared. In the carbon studies, glucose, sucrose, rice flour, and xylan produced similar levels of hydrogen. In the nitrogen studies, Trypticase combined with alternative nitrogen sources can efficiently increases the yield of hydrogen produced by Thermotoga neapolitana. Yeast extract with trypticase as the dual nitrogen sources produced significantly increased …
Biodiesel Forming Reactions Using Heterogneous Catalysis, Yijun Liu
Biodiesel Forming Reactions Using Heterogneous Catalysis, Yijun Liu
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Biodiesel synthesis from biomass provides a means for utilizing effectively renewable resources, a way to convert waste vegetable oils and animal fats to a useful product, a way to recycle carbon dioxide for a combustion fuel, and production of a fuel that is biodegradable, non-toxic, and has a lower emission profile than petroleum-diesel. Free fatty acid (FFA) esterification and triglyceride (TG) transesterification with low molecular weight alcohols constitute the synthetic routes to prepare biodiesel from lipid feedstocks. This project was aimed at developing a better understanding of important fundamental issues involved in heterogeneous catalyzed biodiesel forming reactions using mainly model …
Heterogeneous Catalysis And Biodiesel Forming Reactions, Dora Lopez
Heterogeneous Catalysis And Biodiesel Forming Reactions, Dora Lopez
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Biodiesel, defined as 'a fuel comprised of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats', is finding favor commercially worldwide. The objective of this study is to evaluate the use of solid catalysts for triglyceride transesterification and carboxylic acid esterification to produce biodiesel fuel.
Processes using mainly homogeneous alkali catalysts (such as NaOH, KOH, and methoxides) have been shown to be effective for biodiesel synthesis when dealing with virgin oil feedstocks. Use of acid catalysts (e.g., H2SO4) becomes important when processing low quality feedstocks that contain appreciable amounts of free fatty acids, such as …
Thermodynamic Adsorption Studies Of Peptides On Well-Defined, Surface-Confined Polymers With Applications In Membrane Bioseparations, Nripen Singh
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This dissertation deals with the fundamental studies of peptide adsorption on surfaces modified by surface-confined polymer films, with an application emphasis on membrane bioseparations. In order to understand protein adsorption at a fundamental level, it is important to study the specific residue-level interactions with surfaces. Keeping this idea in view, the present work describes experimental measurements of submolecular-level interaction energies involved in the process of peptide adsorption on polymer films using surface plasmon resonance spectroscopy. Gibbs energy change on adsorption (ΔGad) for tyrosine, phenylalanine, and glycine homopeptides were measured at 25 °C and pH 7 on highly uniform, nanothin polymer …
Kinetics Of Surface-Initiated Photoiniferter-Mediated Photopolymerization And Synthesis Of Stimuli-Responsive Polymer Brushes, Santosh Rahane
Kinetics Of Surface-Initiated Photoiniferter-Mediated Photopolymerization And Synthesis Of Stimuli-Responsive Polymer Brushes, Santosh Rahane
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The focus of this research is to understand the kinetic and mechanistic aspects of surface-initiated photoiniferter-mediated photopolymerization (SI-PMP) and exploit the robustness of SI-PMP to synthesize stimuli-responsive polymer brushes. The 'living' characteristics of dithiocarbamate-based photoiniferter-mediated photopolymerization are well documented. However, in this dissertation I show that the growth of poly(methyl methacrylate) (PMMA) brushes by SI-PMP is nonlinear, suggesting loss of radicals during SI-PMP and, in turn, non-living characteristics. Results from kinetic models in conjunction with experimental results suggest that irreversible bimolecular termination reactions are a primary culprit for the loss of radicals during SI-PMP. To overcome this problem of irreversible …
Using Cross-Sectioned Multilayer Polymer Film And Surface Modification To Form Chemically Patterned Substrates , Chun Zhang
Using Cross-Sectioned Multilayer Polymer Film And Surface Modification To Form Chemically Patterned Substrates , Chun Zhang
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Highly layered structures are important to micro- and nanofabrication technologies for understanding and controlling surface structures through manipulation of chemical and physical interactions. The objective of this work was to develop a new approach to create micro- and nanopatterned surfaces using multilayer polymer films of commercially available and inexpensive polymers instead of inorganic substrates. As an example, linear low density polyethylene (LLDPE) and ethylene-co-acrylic acid copolymer (EAA) were used as alternating inert and reactive polymers, respectively. Thin cross-sections of the multilayer molded sheets were prepared by ultra-microtoming.
As a precursor to the multilayer work, surface modification of EAA was conducted …