Engineering Commons^™

Light-Emitting Nanocomposites And Novel Amorphous Polymers For Optical Applications, Kyle Gipson

All Dissertations

Polymeric optical materials generally are comprised of amorphous polymers that are transparent in at visible wavelengths but exhibit strong absorption bands in the near-infrared making them less useful for many optical applications. Attenuation, which is the absorption per unit length, largely results from the high vibrational energy associated with carbon-hydrogen bonds contained in the polymer backbone. Attenuation can be mitigated by optical amplification utilizing light emitting additives. Investigated in this dissertation are synthesis techniques for the fabrication of light-emitting polymer nanocomposites and their resultant thermal and rheological characteristics for potential use as polymer optical fibers or films.
Inorganic nanocrystals doped …

Adsorption And Diffusion Of Light Hydrocarbons In Ddr Zeolite, Adam Vidoni

Electronic Theses and Dissertations

This thesis reports the results of an experimental study aimed at characterizing the transport properties of DDR crystals (a pure silica zeolite analog) by the “zero length column” technique. This material is potentially useful as a size selective molecular sieve adsorbent for separation of CH₄ – CO₂ in the upgrading of low grade natural gas (or biogas) as well as for the separation of C₃H₆ - C₃H₈ for production of polypropylene. In both these applications pure silica zeolites (such as DDR) have important practical advantages over the traditional cationic zeolites since they …

Response Characterization Of Electroactive Polymers As Mechanical Sensors, G. Alici, Geoffrey M. Spinks, J. D. Madden, Y. Wu, G G. Wallace

Gordon Wallace

The characterization of the dynamic response (including transfer function identification) of trilayer polypyrrole (PPy) type conducting polymer sensors is presented. The sensor was built like a cantilever beam with the free end stimulated through a mechanical lever system, which provided displacement inputs. The voltage generated and current passing between the two outer PPy layers as a result of the input was measured to model the output/input behavior of the sensors based on their experimental current/displacement and voltage/displacement frequency responses. We specifically targeted the low-frequency behavior of the sensor as it is a relatively slowsystem. Experimental transfer function models were generated …

Functional Coatings: Superhydrophopbic And Conductive Coatings, Seyed Amirhossein Seyedmehdi

Electronic Thesis and Dissertation Repository

The natural world has many superhydrophobic and self-cleaning surfaces such as butterfly wings and lotus plant leaves, both well known examples of self-cleaning surfaces. Water droplets on these surfaces can pick up dirt particles and remove contamination. The significant self-cleaning ability of these surfaces has inspired many researchers to attempt to fabricate these superhydrophobic coatings, mimicking their self-cleaning properties, using different methods. Most of the superhydrophobic coatings described in current literature need to be cured in ovens and thus difficult to be applied and/or be maintained in the work place. Therefore, there is a need to develop room temperature curing …

Determining A Method For Rendering Low Cost Cdse(Zns) Core(Shell) Quantum Dots Aqueous Soluble Via Amphiphilic Polymer Wrapping, Patrick Mcbride

Materials Engineering

Herein is described the procedure of two amphiphilic polymer wrapping techniques that may be employed for obtaining aqueous soluble quantum dots (QDs) for use in biological fluorescent imaging applications. The advent of QDs has led to new nanoscale fluorescent materials that exhibit unparalleled quantum yields (QYs), high resistance to photobleaching, tunable emissions, and
absorption over a large optical range. However, the QD synthesis employed here at Cal Poly to obtain bright, photostable CdSe(ZnS) core(shell) QDs involves the use of organic solvents and surfactants, leading to hydrophobic QDs. Since all of biology relies on aqueous solubility, this hydrophobicity creates a major …

Design Of Equipment For The Study Of Non-Isothermal Flow In Polymer Fluid, Opeoluwa Oluwaseun Kolawole

Masters Theses

The polymer industry is an ever growing industry, and, as it grows, companies are continuously looking for ways to study and understand the behaviors of polymers in relation to the processing and production. This is to ensure the production of high quality products and to improve existing products.
An important parameter during polymer processing is temperature. Temperature control affects several rheological parameters such as viscosity, and in turn the quality of the final products. Frictional or viscous heating is a very important part of polymer processing and occurs in almost every polymer processing operation.
The objective of this research is …

Mechanical Evaluation Methods For Polymer And Composite Systems, Donna Theresa Wrublewski

Open Access Dissertations

This dissertation describes the development and application of various mechanical characterization techniques to four types of polymer composite materials. The composite nature of these materials ranges from molecular to macro-scale, as do the size scales probed by the techniques chosen. The two main goals of this work are to evaluate the suitability of existing characterization methods to new composite materials (and augment the methods as needed), and to use these methods to determine optimal composite system parameters to maximize the desired mechanical response. Chapter 2 employs nondestructive ultrasonic spectroscopy for characterizing the stiffness response of both micron-scale woven composites and …

Self-Nucleated Crystallization Of A Branched Polypropylene, Dhwaihi Alotaibi

Masters Theses 1911 - February 2014

Long chain branched polypropylene (LCBPP) crystallizes rapidly and with high nucleation density. The origin of this fast crystallization process is not well understood. It has been attributed to its complicated molecular architecture. In this research, we explore isothermal crystallization of LCBPP, 5%LCBPP and linear polypropylene (LPP) through rheological, thermal, microscopy and optical measurements at different experimental temperatures. The time resolved mechanical spectroscopy technique was used to predict the liquid-to-solid transition (gel point) at different crystallization temperatures (supercooling rates) in order to understand the structure during the crystallization process.

The crystallization process of LCBPP was completed in time scale less …

Development Of Cationic Polymer Coatings To Regulate Foreign-Body Responses, Minglin Ma, Wendy F. Liu, Paulina S. Hill, Kaitlin M. Bratlie, Daniel J. Siegwart, Justin Chin, Miri Park, Joao Guerreiro, Daniel G. Anderson

Kaitlin M. Bratlie

A library of cationic polymers, poly(beta-amino alcohols) with a great chemical diversity are synthesized using combinatorial polymerization. These polymers, when immobilized on a surface, drastically affect the behavior of monocyte/macrophage cells in vitro and early inflammatory reactions in vivo. Certain polymers are found capable of mitigating the foreign-body responses.

Room Temperature Magnetic Materials From Nanostructured Diblock Copolymers, Zoha M. Al-Badri, Raghavendra R. Maddikeri, Yongping Zha, Hitesh D. Thaker, Priyanka Dobriyal, Raja Shunmugam, Thomas P. Russell, Gregory N. Tew

Gregory N. Tew

Nanostructured magnetic materials are important for many advanced applications. Consequently, new methods for their fabrication are critical. However, coupling self-assembly to the generation of magnetic materials in a simple, straight-forward manner has remained elusive. Although several approaches have been considered, most have multiple processing steps, thus diminishing their use of self-assembly to influence magnetic properties. Here we develop novel block copolymers that are preprogrammed with the necessary chemical information to microphase separate and deliver room temperature ferromagnetic properties following a simple heat treatment. The importance of the nanostructured confinement is demonstrated by comparison with the parent homopolymer, which provides only …

Depletion Versus Deflection: How Membrane Bending Can Influence Adhesion, Jin Nam, Maria Santore

Maria Santore

During depletion-driven vesicle adhesion, a stiff membrane’s resistance to bending at fixed tension prevents contact angle equilibrium and vesicle spreading over an opposing vesicle, while more flexible vesicles partially engulf opposing vesicles. Estimates of the bending cost associated with the spreading contact line, relative to the adhesion energy, were consistent with the observed spreading or lack of spreading for the flexible and stiff membranes, respectively, and predicted a lag time sometimes preceding spreading.

Synthesis Of Hydrogels Via Ring-Opening Metathesis Polymerization: Factors Affecting Gelation, Gregory N. Tew, Ahmad E. Madkour, Joshua M. Grolman

Gregory N. Tew

Ring-opening metathesis polymerization (ROMP) was used to synthesize hydrogels via copolymerization of a diamine monomer 3 and a novel cross-linker 5 using Grubbs' third generation catalyst as initiator. Reactions were performed at two different monomer concentrations and at various initial molar ratios of cross-linker to initiator. At low monomer concentration, gelation occurred at initial cross-linker to initiator ratios of 1.5 and greater, which decreased to values of 1.05 and greater when increasing the monomer concentration. This result is in agreement with the Flory–Stockmayer theory. The gel yield and swelling properties were also found to be dependent on the cross-linker to …

Mechanical Characterization Of Polymer Electrolyte Membrane With Optical Methods, Xinyu Huang, Luis Alva, Jay Neutzler

Faculty Publications

Mechanical properties of polymer electrolyte membrane have important implications in the endurance of many electrochemical energy conversion devices [1]. Mechanical experiments are effective method to reveal discrete damage developed in the membrane by quantifying the change of mechanical strength and toughness. Regular strain measurement methods are overly intrusive to the thin and relatively fragile polymer electrolyte membrane; hence optical-based minimal invasive stress/strain measurement methods are studied.