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Full-Text Articles in Engineering Science and Materials

Characterization And Processing Evaluation Of Starch/High-Density Polyethylene Materials In Extrusion Blow Molding, Bradley Dale Bacigalupi Dec 2013

Characterization And Processing Evaluation Of Starch/High-Density Polyethylene Materials In Extrusion Blow Molding, Bradley Dale Bacigalupi

Theses and Dissertations

The growing negative impacts of non-biodegradable plastics derived from non-renewable materials have created increasing interest throughout the world for new materials that are both biodegradable and renewable, that can be combined with or replace traditional plastics. Plant-based thermoplastic starch (TPS), a promising alternative material to traditional petroleum based resin, is both biodegradable and renewable and has great potential for use in plastic manufacturing processes. Two major obstacles that prevent more widespread use of TPS include; TPS base material, which is typically manufactured in a flake or powder, is incompatible with standard plastics production equipment that require pelletized resin, the second ...


Starch Resin Moisture Level Effect On Injection Molding Processability And Molded Part Mechanical Properties With Pure Starch Resin And Polymer Blends, Jordan M. Ellingson Mar 2013

Starch Resin Moisture Level Effect On Injection Molding Processability And Molded Part Mechanical Properties With Pure Starch Resin And Polymer Blends, Jordan M. Ellingson

Theses and Dissertations

The current and forecasted global consumption of plastic packaging and products through the 21st century combined with the already reported and growing negative impact of plastics on the environment due to plastics being synthesized from nonrenewable resources that do not biodegrade is of serious concern. However, recent advances in starch technology including the development of thermoplastic starch (TPS) materials —polymers that are both renewable and biodegradable—have brought hope to reducing this impact. The mechanical properties of thermoplastic starch have often been improved by blending with synthetic polymers. One issue that arises with blending is volatilization of the melt from ...


Friction Stir Spot Welding Of Ultra-High Strength Steel, Trent J. Hartman Aug 2012

Friction Stir Spot Welding Of Ultra-High Strength Steel, Trent J. Hartman

Theses and Dissertations

Friction stir spot welding (FSSW) is quickly becoming a method of interest for welding of high strength steel (HSS) and ultra high strength steel (UHSS). FSSW has been shown to produce high quality welds in these materials, without the drawbacks associated with fusion welding. Tool grade for polycrystalline cubic boron nitride (PCBN) tools has a significant impact on wear resistance, weld quality, and tool failure in FSSW of DP 980 steel sheet. More specifically, for a nominal composition of 90% CBN, the grain size has a significant impact on the wear resistance of the tool. A-type tools performed the best ...


High Speed Friction Stir Spot Welding On Dp 980 Steel:Joint Properties And Tool Wear, Nathan David Saunders Mar 2012

High Speed Friction Stir Spot Welding On Dp 980 Steel:Joint Properties And Tool Wear, Nathan David Saunders

Theses and Dissertations

With the desire to improve passenger safety and fuel efficiency, Ultra High Strength Steels (UHSS) have been developed for use in the automotive industry. UHSS are high strength steels with high ductility and strength. DP 980 is one of these UHSS being applied in automobile manufacturing. DP 980 is difficult to join with Resistance Spot Welding (RSW) because of the high carbon content and alloying in this material. The weld becomes brittle when it solidifies during the welding process. With the desire and motivation of widely using UHSS, new welding processes are needed to be developed in order to effectively ...


Friction Bit Joining Of 5754 Aluminum To Dp980 Ultra-High Strength Steel: A Feasibility Study, Britney Weickum Jul 2011

Friction Bit Joining Of 5754 Aluminum To Dp980 Ultra-High Strength Steel: A Feasibility Study, Britney Weickum

Theses and Dissertations

In this study, the dissimilar metals 5754 aluminum and DP980 ultra-high strength steel were joined using the friction bit joining (FBJ) process. The friction bits were made using one of three steels: 4140, 4340, or H13. Experiments were performed in lap shear, T-peel, and cross tension configurations, with the 0.070" thick 5754 aluminum alloy as the top layer through which the friction bit cut, and the 0.065" thick DP980 as the bottom layer to which the friction bit welded. All experiments were performed using a computer controlled welding machine that was purpose-built and provided by MegaStir Technologies. Through ...


Tool Life Of Various Tool Materials When Friction Spot Welding Dp980 Steel, Christopher Shane Ridges Mar 2011

Tool Life Of Various Tool Materials When Friction Spot Welding Dp980 Steel, Christopher Shane Ridges

Theses and Dissertations

In this study, friction spot welding was used to join DP980 steel sheet. Four different ultra-hard tool materials were used with the objective of determining which tool material produced the highest number of acceptable-strength welds. Three of the tools were composed of various mixtures of polycrystalline cubic Boron Nitride (PCBN), Tungsten, and Rhenium. These materials are referred to herein as Q60, Q70, and Q80, the "Qxx" designation denoting the percentage of the volume of the tool material composed of PCBN. The fourth tool tested was composed entirely of PCBN. The Q70 tool produced approximately 1100 welds of acceptable strength before ...


An Experimental Investigation Of Friction Bit Joining In Az31 Magnesium And Advanced High-Strength Automotive Sheet Steel, Rebecca Gardner Jul 2010

An Experimental Investigation Of Friction Bit Joining In Az31 Magnesium And Advanced High-Strength Automotive Sheet Steel, Rebecca Gardner

Theses and Dissertations

Friction Bit Joining (FBJ) is a recently developed spot joining technology capable of joining dissimilar metals. A consumable bit cuts through the upper layer of metal to be joined, then friction welds to the lower layer. The bit then snaps off, leaving a flange. This research focuses on FBJ using DP980 or DP590 steel as the lower layer, AZ31 magnesium alloy as the top layer, and 4140 or 4130 steel as the bit material. In order to determine optimal settings for the magnesium/steel joints, experimentation was performed using a purpose-built computer controlled welding machine, varying factors such as rotational ...


Natural Fibers And Fiberglass: A Technical And Economic Comparison, Justin Andrew Zsiros Jun 2010

Natural Fibers And Fiberglass: A Technical And Economic Comparison, Justin Andrew Zsiros

Theses and Dissertations

Natural fibers have received attention in recent years because of their minimal environmental impact, reasonably good properties, and low cost. There is a wide variety of natural fibers suitable for composite applications, the most common of which is flax. Flax has advantages in tensile strength, light weight, and low cost over other natural fibers. As with other natural and synthetic fibers, flax is used to reinforce both thermoset and thermoplastic matrices. When flax is used in thermoplastic matrices, polypropylene and polyethylene are the main resins used. Although at first glance flax may seem to be a cheaper alternative to fiberglass ...


Processing A Nickel Nanostrand And Nickel Coated Carbon Fiber Filled Conductive Polyethylene By Injection Molding, David Anthony Whitworth Mar 2010

Processing A Nickel Nanostrand And Nickel Coated Carbon Fiber Filled Conductive Polyethylene By Injection Molding, David Anthony Whitworth

Theses and Dissertations

A new method for pre-impregnating nickel coated carbon fiber with a thermoplastic polymer to make towpreg, similar to a recently developed coating-line by João P. Nunes et al and a new electrically conductive thermoplastic are developed. A melted bath was used to help mitigate health concerns and waste for dispersion of nickel coated carbon fibers (NCF) in low density polyethylene (LDPE). This towpreg was then mixed with more LDPE or a mixture of LDPE and nickel nanostrands (NiNS) to a desired filler volume fraction to test the electrical conductivity of the composite. Some of these mixtures were then injection molded ...