Great Lakes Regional Pollution Prevention Roundtable
Promoting Pollution Prevention Through Information Exchange
GLRPPR Sector Resource: Bio-Based Methodologies for the Production of Environmentally Sustainable Materials
A new SERDP SEED project is currently demonstrating the feasibility of new isocyanate-free solid rocket motor propellant binder formulations for DoD rocket and missile systems by utilizing chemical functionalities and solidification mechanisms found in safe, environmentally-friendly natural products to replace isocyanate cure. The ultimate aim of the effort is to develop an effective means of cure using a selected chemical functionality and mechanism in an energetic binder formulation with no significant loss in performance and insensitivity compared to state-of-the-art formulations, but with significant reductions in environmental, safety and occupational health risks. The main focus of the SEED project is to mitigate the major technical risks associated with the effort by screening candidate functionalities and validating key aspects of performance. To date, the SEED program has made significant progress in screening candidates, with promising results demonstrated in inert formulations. Preparations for testing in energetic formulations are now underway. If successful, this effort will eliminate a significant source of manufacturing risk for solid rocket motor propellants based on ammonium perchlorate, and may also significantly reduce concerns related to process variability and propellant ageing.
Cyanate Ester Composite Resins Derived from Renewable Polyphenol Sources by Dr. Benjamin Harvey
Composite materials consisting of an organic resin and fiber support are widely used throughout the Department of Defense (DoD). Composites provide a number of performance advantages over conventional materials including a significant reduction in weight which results in reduced fuel usage and/or greater range for military platforms. Unfortunately, these environmental benefits are offset by the non-sustainable derivation of polymer composites from petroleum. This presentation will describe recent efforts to develop full performance thermosetting resins from renewable and sustainable polyphenols that can be prepared from biomass sources including lignin, essential oils, natural turpentine and grape skins. In many cases, the structural diversity of the source materials allows for atom-economic routes to new bisphenols that can be used as precursors to both thermosets and thermoplastics. A variety of new resins have been prepared with performance characteristics (e.g., glass transition temperature, water uptake and thermal stability) comparable to and in some cases exceeding those of conventional petroleum-derived resins. Renewable resins have been synthesized on scales of up to one pound and are currently being formulated into bulk molding compounds that can be used for the fabrication of composite parts to replace heavier metal components.
Environmentally Friendly High Performance Bio-Based Polymers for DoD Applications by Dr. John La Scala
Polymer composite materials are derived from non-renewable petroleum sources, making their use unsustainable and causing their cost to be highly volatile. Furthermore, polymer composite materials often contain toxic components or produce toxic emissions. To address these issues, we have used plant-derived renewable resources to develop a number of polymer composite materials technologies with properties and performance similar to that of petroleum-derived composites. We formulated and developed fatty acid-based vinyl ester resins derived from plant oils and successfully demonstrated and validated them on weapons platforms across the DoD. We chemically modified lignin to produce lignin-based carbon fiber with the highest reported strength and modulus. We have been addressing toxicity issues associated with bisphenol, a component used in the production of many high performance polymers. Through use of polymers from lignin-derived chemicals, such as guaiacol, and carbohydrate-derived isosorbide and furans, we have created a number of polymers with properties similar or superior to that of commercial polymers. Furthermore, we have shown that these bio-based chemicals and polymers have reduced toxicity relative to the baseline commercial polymers. As a result, we are currently preparing diamines derived from carbohydrates and lignin to reduce the toxicity and improve the sustainability of polyimides and epoxies.
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