Polymer Science Commons^™

Thermal Damage Approach Of Concrete: Application To Specimens Subjected To Combined Compressive And High Temperature Loads, Abdellah Menou, Ghassan Mounajed, Hocine Boussa, Christian La Borderie, Khalid Lafdi

Khalid Lafdi

Within the framework of study of concrete structures subjected to fire, .a theoretical and experimental work was conducted. The aim of this study was to investigate and to model the damage mechanisms of concrete after their exposure to high temperatures. The multiphase Digital Concrete Model as well as the damage model, MOD EV, which were both implemented on the finiteelem~ rit software package, SYMPHONIE, were used simμltaneously to assess the thermal damage of the concrete. In order to validate the thermal damage model, an experimental investigation was performed. The mechanical characteristics of 5 cementitious materials, which included cement paste, mortar ...

Studies On Nanocomposite Coating Produced By Laser-Assisted Process To Prevent Silicone Hydrogels From Bio-Fouling, Vishnuvardhana Wuppaladhodi

Electronic Thesis and Dissertation Repository

In this thesis, silver nanoparticles incorporated into polyvinylpyrrolidone (PVP) were deposited on silicone hydrogel to improve the hydrophilicity of the silicone hydrogel and prevent the growth of bacteria. Two different processes were employed to produce Ag nanoparticles: (1) Process-A is a photochemical reduction; (2) Process-B is laser ablation in liquid. Following that, MAPLE process was employed to deposit the Ag-PVP nanocomposites on the surface of silicone hydrogel. A solid-state pulsed laser (Nd:YAG) with a wavelength of 532 nm at a fluence of 50.4 mJ/cm² was used in the MAPLE system to deposit Ag-PVP nanocomposite coating. Our ...

Effect Of Cenospheric Fillers On The Flammability And Fire Hazard Of Silicone Rubber Composites, Przemyslaw Rybiński, Witold Zukowski, Dariusz Bradło

Witold Zukowski

Directed Self-Assembly Of Block Copolymer, No1, Hiromichi Yamamoto

Protocols and Reports

The PS-rich and neutral PS-b-PMMA block copolymer (BCP) films were spin coated on the neutral random copolymer hydroxyl-terminated PS-r-PMMA layers grafted on the native oxide and 50 nm thick PECVD amorphous silicon oxide layers. Relationship between the grafting density of BCP and surface density of hydroxyl moiety on silicon oxide is discussed. Furthermore, optimization of annealing BCP films is reported, and wetted and de-wetted BCP films are shown in optical microscope images. In addition, finger print and nanopore structures of BCP films are also indicated in SEM images.

Mass And Charge Transport In Hydrated Polymeric Membranes, Marshall T. Mcdonnell

Doctoral Dissertations

Mass and charge transport through hydrated polymer membranes has significant importance for many areas of engineering and industry. Multi-scale modeling and simulation techniques were used to study transport in relation to two specific membrane applications: (1) food packaging and (2) additives for polymer electrolytes.

Chitosan/chitin films were studied due to their use as a sustainable, biodegradable food packaging film. The effects of hydration on the solvation, diffusivity, solubility, and permeability of oxygen molecules in these films were studied via molecular dynamics and confined random walk simulations. With increasing hydration, the membrane was observed to have a more homogeneous water ...

Film Performance Of Poly(Lactic Acid) Blends For Packaging Applications, Carlos A. Diaz, Hsunpao Y. Pao, Sungyoung Kim

Journal of Applied Packaging Research

Poly(lactic acid) (PLA), a biodegradable thermoplastic derived from renewable resources, stands out as a substitute to petroleum-based plastics. PLA based films for food packaging has been an area of both commercial and research interest within the context of sustainability. In spite of its high strength, packaging applications have been limited because PLA is more brittle than traditional oil-based plastics. Because of this, films display low tear and impact resistance and produce a loud crackling sound when manipulated. Although many studies address the toughening of PLA in the bulk, little attention has been placed on the film performance. The present ...

Occurrence Of Reverse Side Effects In Corona Treatment Of Dispersion-Coated Paperboard And Its Influence On Grease Barrier Properties, Sami-Seppo Ovaska, Ringaudas Rinkunas, Tadeusz Lozovksi, Robertas Maldzius, Jonas Sidaravicius, Leena-Sisko Johansson, Monika Österberg, Kaj Backfolk

Journal of Applied Packaging Research

The uncoated side of dispersion-barrier-coated paperboards was exposed to positive and negative direct current corona treatments in order to confirm the occurrence of backside treatment and clarify its effects on the usability of the paperboard. The main component of the coating dispersions was hydroxypropylated potato starch and the effects of talc and styrene-butadiene latex additions on backside treatment were evaluated. Coatings with a high talc proportion showed excellent initial grease resistance, but corona-induced strikethroughs caused a drastic decrease in grease penetration time. The root-mean-square roughness measurements revealed moderate surface roughening at the backside, indicating thus backside treatment. The alterations in ...

Biodegradable Magnesium Alloys For Orthopaedic Applications: A Review On Corrosion, Biocompatibility And Surface Modifications., Sankalp Agarwal, James Curtin, Brendan Duffy, Swarna Jaiswal

Articles

Magnesium (Mg) and its alloys have been extensively explored as potential biodegradable implant materials for orthopaedic applications (e.g. Fracture fixation). However, the rapid corrosion of Mg based alloys in physiological conditions has delayed their introduction for therapeutic applications to date. The present review focuses on corrosion, biocompatibility and surface modifications of biodegradable Mg alloys for orthopaedic applications. Initially, the corrosion behaviour of Mg alloys and the effect of alloying elements on corrosion and biocompatibility is discussed. Furthermore, the influence of polymeric deposit coatings, namely sol-gel, synthetic aliphatic polyesters and natural polymers on corrosion and biological performance of Mg and ...

Microstructure And Rheology Of Carbon Nanotubes At Air-Water Interfaces, Charles D. Young

Honors Scholar Theses

This work characterizes the material properties of carbon nanotubes at air-water interfaces for potential use in creating stable emulsions. Properties such as length, aspect ratio, contact angle, microstructural ordering, surface pressure, compression and shear elastic moduli, stresses, surface viscosities and non-linearity are explored. Challenges such as deviation from a classical analysis of monolayers are encountered in the form of aggregation, mechanical contributions, and interface relaxation. These factors are taken into account to explain experimental measurements and trends. Ultimately, existing models for more homogeneous systems are resolved with observations to offer insight and areas of promise moving forward.

Synthesis And Characterization Of Interpenetrating Polymer Networks For Applications In Extraterrestrial Radiation Shielding, Josiah Arevalo Hammack

College of William & Mary Undergraduate Honors Theses

During interplanetary voyages spacecraft are exposed to a variety of ionizing radiations, including high intensity electromagnetic radiation and galactic cosmic rays, creating conditions that are harmful to both instrumentation and human passengers. Current shielding methods offer a degree of protection, but they are not suitable for long term missions or for habitation on extraterrestrial environments, and traditional terrestrial shields are too heavy to be carried on these missions. Organic polymers offer a versatile, lightweight solution to many of the difficulties in shielding, however they also present difficulties establishing a sufficiently high hydrogen content while maintaining high mechanical and thermal stability ...

Polymer System And Molding Techniques For Surgical Training Models, Daniel J. Park

Electronic Thesis and Dissertation Repository

Poly(vinyl alcohol) (PVA) hydrogels are used to produce high fidelity models for surgical training applications. PVA hydrogel mechanical properties are developed through the use of a freeze-thaw cycling, physical crosslinking process. The resulting gels exhibit a non-linear elastic modulus which can be tailored to match many tissues of the human body.

Methods for joining PVA hydrogels were investigated to aid in the production of complicated structures that would be difficult to produce in a single step. Bond strength of PVA gels was characterized using a modified peel test. The porosity and degree of crosslinking of the PVA substrate were ...

Design And Implementation Of Multi-Responsive Azobenzene Triggers In Self-Immolative And Degradable Polymers, Andrew D. Wong

Electronic Thesis and Dissertation Repository

Self-immolative polymers are a recently developed class of degradable polymers capable of undergoing end-to-end depolymerization following the reaction of their endcaps with appropriate stimuli. Self-immolative materials originated in the field of prodrug chemistry, and evolved into self-immolative oligomers, dendrimers, and most recently, linear polymers. Many stimuli-responsive endcaps have been developed, but typically can only respond to one stimulus. Azobenzenes are a well-known class of stimuli-responsive molecules most commonly used as photoswitches, due to their facile trans-cis isomerization. In addition to their photochemistry, azobenzenes have recently been found to be selectively reduction-sensitive, and are therefore of interest as endcaps in ...

The Effect Of Assembly Technique On Weak Polyelectrolyte Multilayer Film Morphology And Humidity Swelling/Deswelling Behavior, Ziyang Yin

Graduate Theses - Chemical Engineering

The goal of this research is to investigate the film morphology and humidity swelling/deswelling behavior of polyelectrolyte multilayers (PEMs) that are constructed from poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) by two assembly techniques: automated dipping layer-by-layer (LbL) and spin-assisted (SA) LbL. Two sets of pH polyelectrolyte solution conditions were tested: (PAH7.5/PAA3.5) and (PAH7.0/PAA7.0). It was found that when the films were constructed with the same number of bilayers (=20 bilayers), SA-LbL (PAH7.5/PAA3.5) has a greater thickness than (PAH7.0/PAA7.0). (PAH7.5/PAA3.5) thin films ...

Cfd Simulations And Experiments Of Meltblown Fibrous Media: New Die Designs To Enhance Fiber Attenuation And Filtration Quality, Mohammad Hassan

Mohammad Abouelreesh Hassan

Fabrication Of Micro-Meltblown Filtration Media Using Parallel Plate Die Design, Mohammad Hassan

Mohammad Abouelreesh Hassan

Surface-Initiated Polymerizations For The Rapid Sorting Of Rare Cancer Cells, Jacob L. Lilly

Theses and Dissertations--Chemical and Materials Engineering

Cancer metastasis directly accounts for an estimated 90% of all cancer related deaths and is correlated with the presence of malignant cells in systemic circulation. This observed relationship has prompted efforts to develop a fluid biopsy, with the goal of detecting these rare cells in patient peripheral blood as surrogate markers for metastatic disease as a partial replacement or supplement to tissue biopsies. Numerous platforms have been designed, yet these have generally failed to support a reliable fluid biopsy due to poor performance parameters such as low throughput, low purity of enriched antigen positive cells, and insufficiently low detection thresholds ...

Synthesis And Characterization Of Curcumin Polymer For Application In Radiation Induced Lung Damage, Mark C. Bailey

Theses and Dissertations--Chemical and Materials Engineering

Radiotherapy is used as a primary treatment for many cancers, including lung cancer. Although radiotherapy has proven to be an effective cancer treatment, its use is heavily limited due to the peripheral toxicity to healthy tissue. In this work, the antioxidant, curcumin, was tested as a radioprotectant to reduce radiation damage to healthy cells. Curcumin has been limited in use due to its poor bioavailability. In order to avoid problems associated with free curcumin delivery, curcumin poly(beta-amino ester) (CPBAE) was synthesized.

The first study investigated the in vitro radioprotection effect of curcumin in HUVEC dosed with gamma radiation. Cells ...

Integrated Solar Technologies With Outdoor Pedestrian Bridge Superstructure Decking, Richard K. Racz Mr., Richard Racz

Masters Theses May 2014 - current

Solar technology has been a major topic in sustainable design for many years. In the last five years, however, the solar technology industry has seen a rapid growth in installations and technological advances in cell design. Combined with a rapidly declining overall system cost, the idea of introducing solar technology into a wider range of applications is becoming a focus for engineers and scientists around the world. So many variables which alter solar energy production, such as the sun and surrounding environment, determine whether a solar design is beneficial. This thesis presents a bridge deck surface integrated with solar cells ...

Smart Fabrics For Colorimetric Detection, Breland Edwards

Undergraduate Research Posters

Due to the prevalence of chemical warfare, soldiers often carry chemical sensing devices, to warn of oncoming nerve agents. However, these devices are cumbersome. A lightweight, wearable chemical sensing fabric that doubles as a protectant against toxins would be beneficial. This fabric can be created by incorporating (1) organophosphate hydrolase, an enzyme capable of degrading organophosphates and releasing an acidic by product, and (2) polyaniline, a color changing polymer that changes from purple to green in the presence of acid, into nylon or polyvinyl alcohol nanofibers. The first step is to produce fabrics containing polyaniline and demonstrate that the fabrics ...

Polycaprolactone Nanofiber Scaffold Variants For Human Periosteal Cell Growth, Christopher W. Burton

Honors Research Projects

Polycaprolactone (PCL) nanofiber scaffolds with attached periosteal cells were investigated in this study for a tissue-engineering approach to repair damaged non-union injuries of periosteal tissue and bone. The research purpose was to determine whether this type of scaffold may be utilized as a substrate for periosteal tissue regeneration and to determine whether addition of silica nanoparticles (nSiO₂) to PCL scaffolds enhanced the growth of cadaveric (donor) human periosteal cells in vitro. Electrospun PCL nanofiber scaffolds were fabricated with different silica additions (0, 0.5 and 1.0%) and utilized as substrates on which periosteal cells were seeded. Cell growth ...