Resin impregnated composite fiber reinforcements (prepregs) require nearly continuous refrigeration from the point of manufacture to consumption. Refrigeration impedes curing of the resin and therefore dominates the entire handling process. Refrigeration begins immediately after manufacture and continues until parts are made. This includes pre-shipment freezer storage, special packaging with dry ice and refrigerator trucks for transportation, and freezer storage at the user's facility. With a limited shelf life under refrigeration and a much shorter life when not refrigerated, out-time is the dominant factor in determining hoe the rate of use is managed by the end user. Unused materials must be refrozen until consumed before their shelf life expires or their out-time is exceeded, at which point prepregs are scrapped and become an environmental landfill concern. Long term ambient temperature storability of thermoset prepreg is a major factor in reducing overall costs of advanced composite structures in defense, aerospace, and commercial applications. The principles of resin chemistry which afford room temperature storage play a key role in lowering curing costs by a characteristic behavior known as solid state curing. Solid state curing will be further investigated in Phase II work.
Benefits: Reduces handling costs; eliminates freezer costs; eliminates storage related scrapping; recyclable or convertible to other material forms on sire; greatly minimizes any waste or hazardous material disposal issues; reduces overall cost of composite materials purchased for a program. Adaptable to field repairs and battle damage repair applications.
