Engineering topics

Edwards, Stephanie L.

Publications and source records attributed to Edwards, Stephanie L..

3 records

DOE OSTI2013

Aging Studies on Nitro-Plasticizer

Plasticizers are utilized with many polymers to increase fluidity. By adding a plasticizer to a polymer, the polymer changes from rigid and brittle to soft and flexible. NP is a nitro-plasticizer that is currently used with a wide variety of polymers. NP is a 50-50 mixture of bis(2,2–dinitropropyl) acetal (BDNPA) and bis(2,2 – dinitropropyl)formal (BDNPF) (Figure 1). Sometimes this combination is referred to as A/F but throughout the extent of this paper it will be referred to as NP. BDNPA and BDNPF have been researched separately to determine the decomposition rate of both compounds and what products are generated (3). BDNPF decomposes at a slower rate than BDNPA. It has been hypothesized that this is because BDNPF has a lower vapor pressure and is less sterically hindered (3). It is important to determine how the decomposition of NP will differ as it is a combination of both BDNPF and BDNPA. This particular combination of plasticizers is commonly used with polymers in explosive and propellant composite systems as an energetic plasticizer (3). Because of its applications; it is vital to study to effects of aging on NP to determine its stability over time. This research focuses on 3 and 6 month aged NP and the structural variations that occur due to the aging process. Previous studies suggest that NP is stable during low temperature storage (4), but this research focuses on the stability of NP at various different conditions to achieve the most comprehensive scope of the effect of the aging process. This is an ongoing process and this research will continue to be monitored for at least one year. Depending on the results obtained; the research may carry on for two years.

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DOE OSTI2013

The Effects of Temperature, Aging, and Plasticizer Content on VCE

Ethylene vinyl acetate vinyl alcohol (VCE) is a terpolymer. It is commonly used as a binder for highly filled elastomeric materials (2). Because of its use, it is important that it is studied extensively to ascertain the possible risks. It is crucial to know how VCE is affected by temperature, aging and how plasticizers may affect this polymer. Aging can be tested experimentally by using different temperatures and heating rates and times. If the VCE breaks down or reacts it could be detrimental to the application and there could be safety concerns. The starting copolymer in the synthesis of VCE is ethylene vinyl acetate (EVA).

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DOE OSTI2013

The Use of Dendrimers in Supercapacitors

Dendrimers are large molecules with a tree-like branching structure. They are nearly perfectly monodisperse unlike many linear polymers and can be a variety of sizes. Because of their unique structure they have improved physical and chemical properties. These properties make dendrimers a topic of great interest. There are three important features of dendrimers; the core, the branched groups (generations), and the end groups (Figure 1). These features make up the distinctive structure of dendrimers and are the reason that there are many applications that are unique to these molecules. The generation number affects the size while the terminal end groups are responsible for a great deal of the other properties. Dendrimers that have hydrophilic end groups are soluble in polar solvents while others are not. This flexibility allows a researcher to find a dendrimer that is tailored to their exact needs. Some of the common uses of dendrimers include detecting agents, targeting compounds, and imaging agents. Because of the core and end groups, there is interest in these compounds for encapsulating drugs. Dendrimers can be small enough to pass through cells and since their end groups affect their solubility; they can transport drugs throughout the body.

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