Polymer and Organic Materials Commons^™

Temperature Dependent Surface Reconstruction Of Freely Suspended Films Of 4-N-Heptyloxybenzylidene-4-N-Heptylaniline, Daniel E. Martinez Zambrano

Lawrence University Honors Projects

Surfaces of freely suspended thick films of 4-n-heptyloxybenzylidene-4-n-heptylaniline (7O.7) in the crystalline-B phase have been imaged using non-contact mode atomic force microscopy. Steps are observed on the surface of the film with a height of 3.0 +/- 0.1 nm corresponding to the upright molecular length of 7O.7. In addition, we find that the step width varies with temperature between 56 and 59 degrees C. The steps are many times wider than the molecular length, suggesting that the steps are not on the surface but instead originate from edge dislocations in the interior. Using a strain model for liquid crystalline layers …

Effect Of Heat Treatment On The Mechanical Properties In Natural Bamboo, Austin Levy, Mackenzie Kirkpatrick

Materials Engineering

Previous studies have shown that heat treatments have the ability to improve mechanical strength and stiffness in hardwood species. Compared to structural hardwoods, bamboo is a more sustainable and globally viable renewable resource. Therefore, Bambusoides vivax (timber bamboo) culms were fabricated into flat, rectangular cross-section samples with varying cellulose content to be heat treated and tested for mechanical properties. All samples were heat treated (HT) twice. The first HT was a normalization of all samples at 103 +/- 3 °C. The second HT was performed at various times and temperatures ranging from 130°C to 170°C for 0.5 to 3 hours. …

Minimizing Sheet Resistance Of Organic Photovoltaic Cell Top Contact Electrode Layer: Silver Nanowire Concentration Vs. Conductive Polymer Doping Concentration, Caitlyn Cook

Materials Engineering

The top contact electrode layers of nine organic photovoltaic cells were prepared with two varying factors: three Silver nanowire (AgNW) densities deposited on a conductive polymer doped with three concentrations. Silver’s low sheet resistance of 20-Ω/sq is hypothesized to lower the sheet resistance of the anode layer and thus enhance the overall efficiency of the cell. Four-point probe measurements indicated that increasing AgNW density in the top contact electrode layer of an organic photovoltaic cell significantly reduces sheet resistance from 52.2k-Ω/sq to 18.0 Ω/sq. Although an increase in doping concentration of the conductive polymer reduced sheet resistance in low AgNW …

Effect Of Time Delay Between Etching And Adhesive Bonding (“Outlife” Time) On Lap-Shear Strength Of Aluminum Alloys Using Environmentally-Friendly P2 Etch, Josh Barkhimer, Matthew Erich, Gokul Nair

Materials Engineering

Raytheon Company currently uses a Forest Products Laboratory (FPL) paste etchant for preparing aluminum surfaces for adhesive bonding, and FPL is a source of hazardous hexavalent chromium. The goal of this study was to evaluate a less-toxic P2 paste etchant as a possible replacement. Coupons of 2024-T3, 6061-T6, and 7075-T6 grades of aluminum alloy were solvent-degreased, abrasively cleaned, and etched at room temperature using P2 paste following a strict protocol adopted from Raytheon. Coupons were then left exposed to air for assigned time intervals (or “outlife” times) of 0, 1, 4, 8, 16, and 63 or 72 hours. The aluminum …

Molecular Dynamics Investigation Of The Arabinan-Cellulose Interface For Cellulose Nanocomposite Applications, Luke Thornley

Materials Engineering

Atom level computer simulations of the arabinan and cellulose interface were performed to better understand the mechanisms that give arabinan-cellulose composites (ArCCs) their strength with the goal to improve man-made ArCCs. The molecular dynamics (MD) software LAMMPS was used in conjunction with the ReaxFF/c force field to model the bond between cellulose and arabinan. A cellulose nanocrystal with dimensions 51 x 32 x 8 Å was minimized with various weight percent of water, 0%, 3%, 5%, 8%, 10%, and 12%. After the system was equilibrated for at least 100,000 femtoseconds, an arabinan molecule composed of 8 arabinose rings was added …

Self-Contained Breathing Apparatus For Firefighter With A Permanent Stoma, Jason Delgadillo, Aaron Wheeler, Zachary Wishbow

Biomedical Engineering

The purpose of this project was to create a unique SCBA (self-contained breathing apparatus) for a firefighter named Chris Gauer. This prototype consists of a SCBA headgear connected to a polycarbonate-formed stoma mask with a medical-grade sanitary silicone hose.

Effect Of Surfactant Architecture On Conformational Transitions Of Conjugated Polyelectrolytes, Greg A. Braggin

Master's Theses

Water soluble conjugated polyelectrolytes (CPEs), which fall under the category of conductive polymers, possess numerous advantages over other conductive materials for the fabrication of electronic devices. Namely, the processing of water soluble conjugated polyelectrolytes into thin film electronic devices is much less costly as compared to the processing of inorganic materials. Moreover, the handling of conjugated polyelectrolytes can be performed in a much more environmentally friendly manner than in the processing of other conjugated polymers because conjugated polyelectrolytes are water soluble, whereas other polymers will only dissolve in toxic organic solvents. The processing of electronic devices containing inorganic constituents such …

Predictive Modeling Of Oxygen Transmission Through Micro-Perforations For Packaging Applications, Ayman Abdellatief, Bruce A. Welt, Jason Butler, Eric Mclamore, Arthur Teixeira, Sanjay Shukla

Journal of Applied Packaging Research

Methods for creating precise perforations in respiring produce packaging are being increasingly adopted. Knowledge of oxygen transfer through perforated packaging and oxygen distribution in packages is necessary for successful packaging design of fresh produce. An approach to modeling perforated packaging performance was developed using a cylindrical chamber with precision perforations using Fick’s second law. The model was simulated using two techniques including Finite Element Method (FEM) using commercially available software and Finite Volume Method (FVM) through programming. Perforations were approximated as a source term in the second method. Both simulation techniques showed trends similar to experimental data.

Feasibility Study: The Evaluation Of Polymer Coatings To Prevent Weathering Of Weak Rocks, Lauren Distler

Senior Honors Projects, 2010-2019

The weathering and erosion of weak rocks along roadways can cause dangerous and potentially fatal rockfalls.   Various slope stabilization methods exist, but each presents a set of challenges and trade-offs.   The focus of the project is to understand the feasibility of utilizing of a polymerbased slope stabilization technique. Rock samples were collected along US Route 33 in Virginia and West Virginia, and preliminary tests were conducted to evaluate the absorption of water (% mass) and durability. The study evaluates three polymer options in regard to the following criteria: adhesion to rock, layer thickness, semi-permeability, insolubility, and non-toxicity. The polymer selection …

Material Coefficient Of Thermal Expansion Investigation For Use In Additive Manufacturing Fused Deposition Modeling For Composite Tooling, Daniel Joseph Miller

Master's Theses

Polymer matrix composites are being used to manufacture light weight, high stiffness aircraft structures. These structures are often manufactured from carbon fiber reinforced epoxy. When these structures are damaged, they must be repaired to restore strength to the component to avoid the cost and logistics of having replacements parts. Occasionally, these repairs require tooling in order to make a quality repair, however, tooling generally has a long lead time. Additive manufacturing could be used to manufacture rapid tooling to create tooling for composite repairs. The issue is that polymer printed tooling has a much higher coefficient of thermal expansion (CTE) …

Cure Kinetics, Morphologies, And Mechanical Properties Of Thermoplastic/Mwcnt Modified Multifunctional Glassy Epoxies Prepared Via Continuous Reaction Methods, Xiaole Cheng

Dissertations

The primary goal of this dissertation is to develop a novel continuous reactor method to prepare partially cured epoxy prepolymers for aerospace prepreg applications with the aim of replacing traditional batch reactors. Compared to batch reactors, the continuous reactor is capable of solubilizing and dispersing a broad range of additives including thermoplastic tougheners, stabilizers, nanoparticles and curatives and advancing epoxy molecular weights and viscosities while reducing energy consumption.

In order to prove this concept, polyethersulfone (PES) modified 4, 4’-diaminodiphenylsulfone (44DDS)/tetraglycidyl-4, 4’-diaminodiphenylmethane (TGDDM) epoxy prepolymers were firstly prepared using both continuous reactor and batch reactor methods. Kinetic studies confirmed the chain …

Electrospinning Of Polycaprolactone Core-Shell Nanofibers With Anti-Cancer Drug, Sakib Iqbal, Mujibur Khan, Saheem Absar, Andrew Diamanduros, Samuel Chambers

GS4 Student Scholars Symposium

Encapsulation of a model anti-cancer drug, 5-Fluorouracul (5-FU) into biocompatible core-shell nanofibers of polycaprolactone (PCL) nanofibers was fabricated using a coaxial electrospinning process. Our work aims to solve these issues using a novel method of fabrication of fibers featuring confinement of drugs within a biodegradable core-shell structure, thereby permitting sustained release of drugs to specific sites of treatment, such as tissues affected with tumor cells. The coaxial electrospinning was performed using a sheath polymer solution consisting of a 14 wt% PCL solution and a 5 wt% solution of 5-FU as the core solution. Dimethylformamide (DMF) was used as the solvent …

Optimization Of Graphene-Based Materials Outperforming Host Epoxy Matrices, Liberata Guadagno, Marialuigia Raimondo, Luigi Vertuccio, Marco Mauro, Gaetano Guerra, Khalid Lafdi, Biagio De Vivo, Patrizia Lamberti, Giovanni Spinelli, Vincenzo Tucci

Chemical and Materials Engineering Faculty Publications

The degree of graphite exfoliation and edge-carboxylated layers can be controlled and balanced to design lightweight materials characterized by both low electrical percolation thresholds (EPT) and improved mechanical properties. So far, this challenging task has been undoubtedly very hard to achieve.

The results presented in this paper highlight the effect of exfoliation degree and the role of edge-carboxylated graphite layers to give self-assembled structures embedded in the polymeric matrix. Graphene layers inside the matrix may serve as building blocks of complex systems that could outperform the host matrix. Improvements in electrical percolation and mechanical performance have been obtained by a …

Process And Apparatus For Manufacturing Grease, Lou A. T. Honary, James E. Wesley

Patents (University of Northern Iowa)

A process and corresponding apparatus and system for use in preparing soaps from fatty acid containing oil compositions, and in turn, for preparing greases by the use of such soaps in combination with one or more base oils.

Methods For Analyzing The Structure Of Creases In Heat Sealed Paperboard Packages, Ville Leminen, Petri Mäkelä, Panu Tanninen, Juha Varis

Journal of Applied Packaging Research

Press-forming of paperboard has been previously studied by several authors. A point of interest regarding gas tight heat sealing of the packages are the creases in the package. The objective of this article was to study and compare different microscopic imaging methods to research an optimal imaging method for the formation of creases in the press-forming process of polymer coated paperboard trays. The studied methods were: Scanning electrode microscopy (SEM), X-ray Microtomography, Optical light microscopy and Polarized light microscopy. All four tested methods delivered clear images. Casting of the samples in an acrylic resin and light microscope imaging was found …

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 …

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 …

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 …