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Articles 1 - 15 of 15
Full-Text Articles in Engineering
Formulation And Optimization Of Algae-Filled Polylactic Acid Thermoplastic Compounds For Improved Biodegradation, Sydney A. Cole
Formulation And Optimization Of Algae-Filled Polylactic Acid Thermoplastic Compounds For Improved Biodegradation, Sydney A. Cole
Honors Theses
Conventional plastics derived from non-renewable petrochemicals – especially from fossil reserves – have become an integral part of human life because their structure can be chemically manipulated to obtain a wide range of properties and geometries necessary in nearly all industries. The volume and rate at which petroleum plastics are produced, used, and discarded has incited several significant issues related to human health, environmental conservation, and ecological biodiversity. To address these issues, many institutions have begun investigating solutions in both the development and end-oflife phases of plastic production and waste. In this thesis, a Chlorella-dominated algae mixture is dried and …
Analysis Of Hemp Fiber Reinforced Polylactide Composite Under High Strain-Rate, Benjamin Rhoads
Analysis Of Hemp Fiber Reinforced Polylactide Composite Under High Strain-Rate, Benjamin Rhoads
Honors Theses
The introduction of hemp fibers into a polylactide (PLA) matrix creates a hemp fiber-reinforced composite with 10% hemp fibers and 90% PLA. Natural fibers are becoming a popular alternative to synthetic fibers since they are environmentally friendly, and hemp-fibers are becoming used more often as the demand for natural fibers increased. A Split-Hopkinson Pressure Bar was used to test this composite against a control group using elastic wave propagation theory. Strain gauges were mounted on the incident and transmission bars of the SHPB to measure the propagation of the wave that caused the strain in the sample, which were used …
Effects Of Static Mixer Geometry On Polyurethane Properties, Christian R. Dixon
Effects Of Static Mixer Geometry On Polyurethane Properties, Christian R. Dixon
Honors Theses
The field of additive manufacturing has gained significant academic interest in the past few decades with a recently developed type of three-dimensional (3D) printing. Reactive extrusion additive manufacturing combines precursor materials within a static mixer (SM) head, where polymerization begins before deposition. Variable static mixer geometries currently exist, but the relationship between mixer geometry and post-polymerization mechanical properties is undefined. To elucidate this relationship, a series of experiments with identical chemistry was performed using a high shear SM, a low shear SM, and a comparative batch reaction. While higher shear mixing trends with faster polymerization for step-growth polymerizations, consistent precursor …
Utilizing The Oxygen-Barrier Properties Of Poly(Isobutylene) To Enhance Photon Upconversion In Thermoplastic Elastomers, Haley Carroll
Utilizing The Oxygen-Barrier Properties Of Poly(Isobutylene) To Enhance Photon Upconversion In Thermoplastic Elastomers, Haley Carroll
Honors Theses
Upconversion (UC) is the conversion of low energy light to higher energy light. It is utilized for a broad range of applications such as solar energy harvesting, microscopy of cellular biology, and cancer therapy. Specifically, triplet-triplet annihilation UC (TTA-UC) involves two dye species, a sensitizer and an annihilator, which are capable of upconverting noncoherent light such as sunlight. Traditionally, TTA-UC is achieved in solution, rubbers, or glasses, however, this work probes the capabilities of a thermoplastic elastomer (TPE) matrix to examine the effect of phase-separated morphology on the energy transfers necessary for TTA-UC. The system herein consists of poly(styrene-isobutylene-styrene) (SIBstar) …
Determination Of Hydrogel Degradation By Passive Mechanical Testing, Avery Rosh-Gorsky
Determination Of Hydrogel Degradation By Passive Mechanical Testing, Avery Rosh-Gorsky
Honors Theses
This paper details a new technique to measure the mechanical properties of ETTMP PEGDA hydrogels using Hertz Contact Theory and simultaneously analyze both the model drug release and gel erosion in situ. This method involves curing a drug loaded hydrogel in a standard cuvette and placing a glass bead and phosphate buffer solution (PBS). Over time, the cross-linked network of the hydrogel breaks down, and, as a result, the ball sinks into the hydrogel. This method provides a macroscopic and inexpensive way to continuously and passively measure properties of the hydrogel as the hydrogel degrades. By plotting both the …
Selfsame Epoxide-Amine Microparticle Systems: Investigation Of Crosslink Density, John J. Peyrefitte
Selfsame Epoxide-Amine Microparticle Systems: Investigation Of Crosslink Density, John J. Peyrefitte
Honors Theses
Epoxide-amine matrix materials containing microparticles with the same chemical composition provide a model system to study interphase formation in highly crosslinked epoxide-amine matrix materials. The epoxide monomer was varied between three different monomer systems to study the model system’s relationship with crosslink density. The same amine monomer, cure procedure, and stoichiometric ratio of epoxide and amine groups were used to prepare each type of microparticle and matrix material. The differences in the epoxide monomer structure affected the crosslink density of the unmodified matrix material, which was concluded to influence the effect of microparticle presence on crosslink density. For the unmodified …
Thiol-Induced Degradation Of Hydrogels Utilizing Multiresponsive Dithiomaleimides Crosslinkers, Kundu Thapa
Thiol-Induced Degradation Of Hydrogels Utilizing Multiresponsive Dithiomaleimides Crosslinkers, Kundu Thapa
Honors Theses
Hydrogels are hydrophilic, three-dimensional materials used as platforms for various biomedical applications such as drug delivery, biosensors, or as scaffolds in tissue engineering. The ability to degrade on demand in response to biological cues is particularly attractive whether dealing with microgels or if one aims to release an active ingredient from a scaffolding material. For instance, many cancer-remediation drug delivery platforms leverage the high concentration of glutathione, a thiol-containing tripeptide, found in cancerous cells. In this work, poly(ethylene glycol) acrylate hydrogels were fabricated using dithiomaleimide (DTM) moieties. DTMs are known to undergo thiol-exchange reactions favoring the dissolution of the hydrogel …
Tailoring Photodegradation Rates Of Acetal-Containing Polymer Networks, Michael Sandoz
Tailoring Photodegradation Rates Of Acetal-Containing Polymer Networks, Michael Sandoz
Honors Theses
In this thesis, we explore the degradation of poly (thioether acetal) thermosets via a photoinduced thiol-catalyzed ß-scission of acetal linkages incorporated as network crosslink junctions. Specifically, a library of bis-allyl acetal-containing monomers derived from para-substituted benzaldehydes was synthesized and formulated into photopolymerizable thiol-ene resins with commercially available thiol monomers. By varying the electron donating or withdrawing nature of the monomer substituent, we explored the impact of substituent effects on the rate of polymer degradation. Furthermore, we compare the results to those expected from a classical Hammett-type relationship of substituent electronic effects. FTIR was employed to track the appearance of the …
Design Of Natural Composite I-Beam For Sampe 2019, Brian Harkness
Design Of Natural Composite I-Beam For Sampe 2019, Brian Harkness
Honors Theses
In recent years, the demand for high performance, lightweight, fiber-reinforced composites have grown substantially. Fiberglass and carbon fiber have exemplary material properties that meet the demand and have set the industry standard for performance materials. Although these materials meet their design function, they suffer from high environmental impacts throughout their life cycle and are not cost effective to produce. Flax fiber composites have comparable properties to fiberglass but can be produced more efficiently and production requires much less energy consumption. Flax is a readily available, renewable material that will easily biodegrade once it is the end of its useful life …
Improved Data Acquisition Using A Novel Dynamic Mechanical Analysis Sample Preparation Technique: The Numbers Do Not Lie, Jordan J. Winetrout
Improved Data Acquisition Using A Novel Dynamic Mechanical Analysis Sample Preparation Technique: The Numbers Do Not Lie, Jordan J. Winetrout
Honors Theses
Dynamic mechanical analysis (DMA) is a technique commonly used to identify the thermomechanical properties of polymeric materials. In the aerospace industry, a typical DMA sample is a glassy epoxy-amine polymer network. On a laboratory scale, these types of materials are cured in a silicon mold and sanded by hand to yield a sample with testable dimensions. This preparation technique is time consuming and causes sample imperfections which negatively affects data acquisition. This thesis aims to absolve the issues with DMA sample preparation by using a custom vacuum housing and a DeWALTTM brand orbital sander. This novel approach has been …
Design Process Of A Novel Dynamic Mechanical Analysis Sample Preparation Methodology, Julian M. Richardson
Design Process Of A Novel Dynamic Mechanical Analysis Sample Preparation Methodology, Julian M. Richardson
Honors Theses
The technique of dynamic mechanical analysis (DMA) has been a frontrunner in the field of polymer science for decades. It’s used as a tool for characterization has been integral in mankind’s understanding of the properties of polymeric materials. The procedure for obtaining data using DMA is widespread and standardized, however the procedure for preparing the samples is a list of dimensions and tolerances with no mention of how to obtain said dimensions. Every research group using DMA is left to their own devices to prepare samples. This discontinuity can create the problem of nonuniform results across the scientific community. This …
Corner Sealants For Tactical Shelters, Janine Carlita Nowak
Corner Sealants For Tactical Shelters, Janine Carlita Nowak
Honors Theses
The demand for a lightweight, easy-assembly tactical shelter is high for those faced with unexpected disasters and global conflicts. This project focuses on designing and prototyping the corner sealant for such a shelter. Two materials were chosen and tested: an in-house thermoplastic polyurethane (TPU) and Texin 950. Thermogravimetric Analysis (TGA) was performed on both of these materials. The in-house TPU showed initial degradation at 282.50 °C and sample degradation at 457.45 °C. Similarly, Texin 950 showed initial degradation at 293.68 °C and sample degradation at 453.26 °C. Differential Scanning Calorimetry (DSC) was then run. The crystallization temperature (Tc) was observed …
Characterization And Selection Of Hydroxyl-Terminated Polybutadiene Polymers For High-Strain Applications, Nathaniel Prine
Characterization And Selection Of Hydroxyl-Terminated Polybutadiene Polymers For High-Strain Applications, Nathaniel Prine
Honors Theses
Understanding the behavior of hydroxyl-terminated polybutadiene (HTPB) as a composite matrix is imperative for the development of future military and aerospace munition technology. As a vital component of solid rocket fuel, HTPB strongly contributes to the fatigue behavior, burn-rate, and other properties that can cause critical failure of the rocket if not formulated properly. The purpose of this research is to identify traits characteristic of poor-performing HTPB matrices by analyzing two samples labeled as either “good” or “bad” based on their performance as a fuel matrix. Samples were analyzed via 1H NMR and GPC to determine their epoxy content, hydroxyl …
Synthesis Of Acceptors For Use In Donor-Acceptor Copolymers And Characterization Of These Polymers, William D. Walker
Synthesis Of Acceptors For Use In Donor-Acceptor Copolymers And Characterization Of These Polymers, William D. Walker
Honors Theses
In this thesis, a selenium-derivatized acceptor was synthesized to examine the heavy atom effects of selenium on the position of the frontier molecular orbitals (HOMO/LUMO band gap) as opposed to sulfur in a donor-acceptor copolymer for use in light harvesting and detection applications. Over the course of this research, standard operating protocols for ultraviolet-visible (UV-Vis-NIR) and Fourier transform infrared (FT-IR) spectroscopies, as well as cyclic voltammetry (CV) characterization techniques were established. Once synthesized, the polymers were characterized through use of the established characterization protocols. The selenium-derivatized polymer exhibited a bathochromic shift compared to the sulfur analogue, with a solid-state absorption …
The Effect Of Cure Rate On Glassy Polymer Networks, Kristen M. Van De Voorde
The Effect Of Cure Rate On Glassy Polymer Networks, Kristen M. Van De Voorde
Honors Theses
The formation of glassy polymer networks such as epoxy-amine systems may be altered by varying the temperature ramp rate that is used to cure the system. As a result, the physical and mechanical properties of the network may be changed. This work synthesized the epoxy resins diglycidyl ether of bisphenol A (DGEBA) with the amine curing agent 4,4-diaminodiphenyl sulfone (4,4’-DDS) from 35°C to 180°C using varying temperature ramp rates. Mechanical and structural properties of these samples were then analyzed to determine the effect the different temperature ramp rates had on the formation and properties of the thermoset matrix. These aspects …