Degradation of Polyurethane Aircraft Coatings Using Gel-Encapsulated Enzymes

By 1996, legislation will eliminate the use of solvent-based chemical strippers containing EPA-listed hazardous air pollutants for the removal of polyurethane-based aircraft coatings. Currently available "green" chemical strippers are much less effective, requiring long application periods and multiple applications. Foster-Miller proposes the development of a robust, enzyme-activated paint removal system that will actively degrade polyurethane-based coatings in an environmentally acceptable manner within a few hours of application. An environmentally benign and biodegradable solvent is first applied to the coating to soften and swell the coating prior to application of the enzyme. The enzyme or a consortia of enzymes are encapsulated and stored in a biodegradable gel, released upon exposure of the gel to the solvent, and degrade the polyurethane coating. The gels provide a formulation that is easy and safe to apply by normally skilled military personnel. The Phase I program focuses on the (a) identification, characterization and selection of both the solvent(s) and enzyme(s) and (b) identification and characterization of biodegradable polymeric gels with respect to the encapsulation and release of model enzymes. The Phase II program involves a field demonstration of the system at an Air Force facility.