Polymer and Organic Materials Commons^™

Computational Multiscale Modeling And Characterization Of Piezoresistivity In Fuzzy Fiber Reinforced Polymer Composites, Xiang Ren, Josh Burton, Gary D. Seidel, Khalid Lafdi

Chemical and Materials Engineering Faculty Publications

In this paper, the piezoresistive response (i.e. the change of resistance under the application of strain) of polymer composites reinforced by a novel material known as fuzzy fibers is characterized by using single tow piezoresistive fragmentation tests and modeled by using a 3D computational multiscale model based on the finite element analysis. In the characterization work, the fuzzy fiber tow is embedded in a dog-bone specimen infused by epoxy, with resistance and displacement measured simultaneously to obtain its piezoresistive response. An approximately linear and stable piezoresistive response is observed within the fuzzy fiber tow region yielding gauge factors on average …

Design And Synthesis Of Low-Bandgap Polymers For Organic Photovoltaic Applications, Letian Dou

Link Foundation Energy Fellowship Reports

This research at UCLA focused on the design and synthesis of novel conjugated polymers as the electron-donor material for photovoltaic devices. By careful molecular design both on the polymer backbone and the side chains, a series of low-bandgap conjugated polymers were synthesized for a variety of photovoltaic applications, including single junction and tandem polymer solar cells. In addition, the author designed and synthesized a novel higly perfect polymer single crystal material via a visible light triggered topochemical reaction. This kind of materials shows high potential for application in solar cells and transistors, which, the author believe, is a huge breakthrough …

Characterization Of Dimethyl Sulfoxide-Treated Wool And Enhancement Of Reactive Wool Dyeing In Non-Aqueous Medium, Luyi Chen, Bijia Wang, Jiangang Chen, Xinhui Ruan, Yiqi Yang

Department of Textiles, Merchandising and Fashion Design: Faculty Publications

Wool pretreated with dimethyl sulfoxide (DMSO) was characterized and its dyeing behavior in non-aqueous green solvents was investigated. Reactive dyeing of wool in deep shades is challenging because the mandatory alkaline aftertreatment to match the fastness of mordant dyes inevitably causes damage to wool keratin. The current study showed that the colorfastness-integrity dilemma could be solved by replacing water with organic solvents as the dyeing medium. Covalent fixation is predominantly favored in solvent dyeing so that excellent colorfastness is achievable at any given shade without alkali aftertreatment. Compared with aqueous dyeing, solvent dyeing was found to give 30% higher covalent …

Temporally And Spatially Resolved Plasma Spectroscopy In Pulsed Laser Deposition Of Ultra-Thin Boron Nitride Films, Nicholas R. Glavin, Christopher Muratore, Michael L. Jespersen, Jianjun Hu, Timothy S. Fisher, Andrey A. Voevodin

Chemical and Materials Engineering Faculty Publications

Physical vapor deposition (PVD) has recently been investigated as a viable, alternative growth technique for two-dimensional materials with multiple benefits over other vapor deposition synthesis methods. The high kinetic energies and chemical reactivities of the condensing species formed from PVD processes can facilitate growth over large areas and at reduced substrate temperatures. In this study, chemistry, kinetic energies, time of flight data, and spatial distributions within a PVD plasma plume ablated from aboron nitride (BN) target by a KrF laser at different pressures of nitrogen gas were investigated. Time resolved spectroscopy and wavelength specific imaging were used to identify and …

3d Printing, Open-Source Technology And Their Applications In Research, Chenlong Zhang

Dissertations, Master's Theses and Master's Reports

Open-source software received tremendous success as it drives down the cost of software and expand the distribution. Open-source hardware, as part of the open-source movement, has just risen into public attention for its potential to further drive down the cost of all kinds of manufacturing goods and reshape the manufacture chain. In this report we explores the history, development and the future of open-source hardware project, summarizing the opportunities, challenges and possible solutions. 3D printing is demonstrated as a booster to assist open-source hardware’s development. Low-cost 3D printer enables at-home and in-time fabrication, the download-print-use-improve-distribute cycle is established to encourage …

The Future Of Carbon-Based Scaffolds In Foot And Ankle Surgery, Jarema S. Czarnecki, Khalid Lafdi, Panagiotis A. Tsonis

Chemical and Materials Engineering Faculty Publications

Autologous grafts have been the gold standard in tissue replacement and the most accurate means of recapitulating both the biological and mechanical properties of tissue. However, autologous grafts have had complications and drawbacks. Skin grafting, a prime example of an autologous tissue graft, has been limited by the size of graft, availability, and secondary donor site morbidity. Use of cadaveric tissues circumvents several limitations of autologous grafts; however, sterilization processes used to reduce the risk of disease transmission potentially weaken tissues and eliminate living cells and some growth factors from scaffolds, making them suboptimal tissue replacements. Chemical cross-linkage of tissue …

Effects Of Disorder State And Interfacial Layer On Thermal Transport In Copper/Diamond System, Vikas Sinha, Jaime J. Gengler, Christopher Muratore, Jonathan E. Spowart

Chemical and Materials Engineering Faculty Publications

The characterization of Cu/diamond interface thermal conductance (h_c) along with an improved understanding of factors affecting it are becoming increasingly important, as Cu-diamond composites are being considered for electronic packaging applications. In this study, ∼90 nm thick Cu layers weredeposited on synthetic and natural single crystal diamond substrates. In several specimens, a Ti-interface layer of thickness ≤3.5 nm was sputtered between the diamond substrate and the Cu top layer. The h_c across Cu/diamond interfaces for specimens with and without a Ti-interface layer was determined usingtime-domain thermoreflectance. The h_c is ∼2× higher for similar interfacial layers on …

Effect Of Nanofiber Morphology On Pvdf Air Filter Performance, Andrew W. Marton

Williams Honors College, Honors Research Projects

Poly(vinylidene fluoride) (PVDF) can be formed into small nanofibers by electrospinning that are useful for a variety of applications. Air filters produced with PVDF are known to capture ionic particles with high efficiency. Existing studies have focused on the effects of electrospinning conditions on nanofiber morphology. In this study fibers were generated with varying morphologies. Air filters were then made from each sample and then characterized by TSI. Air filters were found to have increased resistances relative to their capture efficiencies according to particle diameter. Capture efficiencies did not correlate strongly with particle diameter, and the presence of beads in …

Reusable Adhesive Tapes From Electrospun Polymer Fibers, Vishal K. Chaurasia

Williams Honors College, Honors Research Projects

Many emerging applications demand an adhesive that has reusable properties. The adhesive must exhibit high adhesion strength to various surfaces and be able to be removed easily and then reapplied with minimal to no loss in adhesion strength. This work aims to tackle this problem by creating an adhesive tape fabricated by electrospinning polymer solutions onto a substrate. Electrospun adhesive nano/micro fibers have the ability to display the reusable characteristics desired. Several adhesive custom formulations were first developed and optimized for electrospinning. Then these formulations were successfully electrospun on to various substrates after much fine tuning of electrospinning parameters. The …

Failure Modes For I-Section Gfrp Beams, Mamadou Konate, Zia Razzaq

Civil & Environmental Engineering Faculty Publications

This paper presents calculations for the failure modes for I-section Glass Fiber Reinforced Polymer (GFRP) beams with single mid-span web brace. Theoretical predictions are made using ASCE-LFRD Pre-Standard for FRP structures. For the member length considered, it is found that for small and medium I-sections the failure mode is governed by lateral-torsional buckling and for bigger I-sections the failure mode is governed by material rupture. The outcome of the predicted lateral-torsional buckling mode is compared with that observed experimentally.

Designed Synthesis Of Nanoporous Organic Polymers For Selective Gas Uptake And Catalytic Applications, Pezhman Arab

Theses and Dissertations

Design and synthesis of porous organic polymers have attracted considerable attentions during the past decade due to their wide range of applications in gas storage, gas separation, energy conversion, and catalysis. Porous organic polymers can be pre-synthetically and post-synthetically functionalized with a wide variety of functionalities for desirable applications. Along these pursuits, we introduced new synthetic strategies for preparation of porous organic polymers for selective CO₂ capture.

Porous azo-linked polymers (ALPs) were synthesized by an oxidative reaction of amine-based monomers using copper(I) as a catalyst which leads to azo-linkage formation. ALPs exhibit high surface areas of up to 1200 …

Evaporation-Induced Formation Of Well-Ordered Surface Patterns On Polymer Films, Wei Sun

Theses and Dissertations--Chemical and Materials Engineering

Various techniques of fabricating surface patterns of small scales have been widely studied due to the potential applications of surface patterns in a variety of areas. It is a challenge to fabricate well-ordered surface area efficiently and economically. Evaporation-induced surface patterning is a promising approach to fabricate well-ordered surface patterns over a large area at low cost. In this study, the evaporation-induced surface patterns with controllable geometrical characteristics have been constructed. The dewetting kinetics on deformable substrate is also investigated.

Using simple templates to control the geometry and the evaporation behavior of a droplet of volatile solvent, various gradient surface …

Peracetic Acid Sterilization Of Electrospun Polycaprolactone Scaffolds, Suyog Yoganarasimha

Theses and Dissertations

Sterilization of tissue engineered scaffolds is an important regulatory issue and is at the heart of patient safety. With the introduction of new biomaterials and micro/nano structured scaffolds, it is critical that the mode of sterilization preserve these built-in features. Conventional sterilization methods are not optimal for engineered polymeric systems and hence alternate systems need to be identified and validated. PCL is polyester with a low melting point (heat labile), susceptible to hydrolysis and is popular in tissue engineering. Electrospinning generates some nanoscale features within the scaffold, the integrity of which can be affected by sterilization method. Chapter 1 explores …

The Influence Of Particle Content On The Equi-Biaxial Fatigue Behaviour Of Magnetorheological Elastomers, Yanfen Zhou, Stephen Jerrams, Tony Betts, Gerald Farrell, Lin Chen

Articles

The equi-biaxial fatigue behaviour of silicone based magnetorheological elastomers (MREs) with various volume fractions of carbonyl iron particles ranging between 15% and 35% was studied. Wöhler curves for each material were derived by cycling test samples to failure over a range of stress amplitudes. Changes in complex modulus (E*) and dynamic stored energy during the fatigue process were observed. As for other elastic solids, fatigue resistance of MREs with different particle contents was shown to be dependent on the stress amplitudes applied. MREs with low particle content showed the highest fatigue life at high stress amplitudes while MREs with high …

Systematic Study Of The Biological Effects Of Nitric Oxide (No) Using Innovative No Measurement And Delivery Systems, Weilue He

Dissertations, Master's Theses and Master's Reports

Nitric oxide (NO) is recognized as the most important small signaling molecule in the human body. An imbalance of NO is closely associated with many serious diseases such as neurological disorders, cardiovascular diseases, chronic inflammations and cancers. Herein two chemiluminescence-based devices (a real-time NO measurement device and a controllable NO delivery device) were developed to facilitate the NO quantitative study and obtain information for NO related drug design.

The first device used for real-time measuring NO(g) flux from living cells was developed and validated. The principle was to use a two-chamber design, with a cell culture chamber and a gaseous …