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Easily Processed High Tg polymers


The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with section 3.5 of the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws. OBJECTIVE: Polymers are required which exhibit extremely high glass transition temperatures (> 350 C) but are soluble in commonly used organic solvents such as acetone, ethyl acetate, and chloroform. DESCRIPTION: Novel munition systems currently must contend with extraordinary thermal demands. This has necessitated the development of polymers which can match the rigors associated with state of the art systems. Chiefly, they must maintain great strength and stiffness while under high thermal loads. In order to be processable, however, they must maintain high solubility levels in commonly used solvents so they can still be worked into desired shapes. For example, for many applications they must be able to be cast into thin films. Furthermore, if they can be easily processed, they could then be used in novel energetic formulations as binders. Here, they could impart great stability to energetic formulations, a critical goal in many novel munition systems which will put tremendous thermal load on energetic formulations. Unfortunately, while not mutually exclusive properties, it appears as if many polymers with high glass transition temperatures exhibit poor solubilities. To further the difficulty of the problem, it appears, few, if any polymers currently available have a high enough glass transition temperature to satisfy the needs for the US Army. Therefore, new polymers are required with high glass transition temperatures, but these polymers must also be easily molded into desired shapes, which means they must have high solubility in commonly used organic solvents. They should also exhibit superior mechanical properties through a wide temperature range, as envisioned applications will required relatively high stresses, and often, very high strain rates. These polymers must be manufactured in an environmentally friendly manner, and should be sourced domestically. When possible, issues with foreign/sole sourcing of precursor materials must be addressed. If successful, it is expected this effort would spawn off numerous other programs, for example MANTECHs, and this effort should produce sufficient information to pursue follow on efforts. While interesting in other cases, this effort should NOT focus on use of additives such as nanoclays, carbon nanomaterials etc. The goal of this effort is to obtain the desired properties purely with the polymer. For many use cases, the additives would be a hindrance. PHASE I: Develop polymers at the laboratory scale (~5 grams) and characterize solubility in the following solvents: acetone, ethyl acetate, tetrahydrofuran, ethanol, water, methyl ethyl ketone, methanol, toluene, acetonitrile, and heptane. The polymers should exhibit significant solubility in at least one organic solvent, preferably two or more, and they should be insoluble in water. Important thermal properties such as the glass transition temperature, crystallization temperature, and bulk modulus across a wide temperature range should be reported. The chemistry of the polymer should be mostly optimized at this point. PHASE II: Polymers will be produced in the 100s of gram scale. Here the production of the polymers will be optimized, and any issues with the supply chain must be addressed (such as sourcing precursor materials from foreign and/or sole sources). Pricing of the polymers will be estimated under the assumption of an annual buy of ~100 Kg. The polymer properties should be optimized at this phase for the most likely applications, to be further explored in phase 3. Molecular weight is a key consideration in this phase. Aging studies should be conducted at this stage, to determine the suitability for long term usage. High strain testing of the properties of these materials should be conducted, but the US Army will be able to provide such characterization at this stage if required. The polymers should now be ready for use in engineering type tests, where they should be provided to the US DoD in the desired configuration. The US DoD will require 500 grams of each polymer for further evaluation in this phase. PHASE III DUAL USE APPLICATIONS: Kilogram scale quantities of the 1-3 downselected polymers will be produced to support identified applications of interest. The polymers must be processed into a form usable for the US government. The polymers must be delivered to a US DoD installation, or a US DoD funded contractor before the end of project for a full scale evaluation. At this point, engineering tests should be performed on the polymers in the desired system, and if issues arise, further customization might be required. High Tg polymers also offer a number of advantages in numerous industries, with the most dramatic example being those in space. This is because high Tg polymers are generally speaking offer extremely good strength to weight ratios, while maintaining properties across a wide temperature range. They are even useful for ‘exotic’ propulsion such as those using solar sails. A significant advance in high Tg polymers, therefore, should attract commercial interest as well. REFERENCES: 1. Disordered Materials: An Introduction by Paolo M. Ossi, Springer-Verlag Berlin Heidelberg, 2006; 2. Principles of Polymerization, Fourth Edition, George Odian, John Wiley & Sons, Inc. 2004; 3. Physical Properties of Polymers Handbook, James E. Mark, ACS Professional 1994; 4. The Glass Transition, Relaxation Dynamics in Liquids and Disordered Materials, E. Donth, Springer 2001; 5. Relaxation in glassforming liquids and amorphous solids, C. Austin Angell, Kia L. Ngai, Gregory McKenna, Paul F. McMillan, Steve W. Martin, Journal of Applied Physics 2008 KEYWORDS: Polymers, High Glass Transition, Thermally Stable, Solubility, Strength, Stiffness, Mechanical Properties, High Crystallization Temperature
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