SHEAR RATE DETERMINATION FOR TWIN SCREW CONTINUOUS PBX PROCESSING

THE PROPOSED RESEARCH ADDRESSES THE NEED FOR A SIMPLE, VISUAL METHOD TO DETERMINE THE SHEAR RATE EXPERIENCED IN A TWIN SCREW CONTINUOUS MIXER WHERE ENERGETIC PBX MATERIALS ARE MIXED. THE SCOPE OF THIS PROPOSAL IS TO DETERMINE THE FEASIBILITY OF ADDING SMALL QUANTITIES OF VARIOUS DRY FREE FLOWING MICROENCAPSULATED TAGGANT MATERIALS TO A SIMULATED NON-ENERGETIC PBX PROTOTYPE FORMULATION AND SUBJECTING THOSE MIXES TO THE SHEAR FORCES WITHIN A LABORATORY TWIN SCREW MIXER. SHEARING CONDITIONS EXPERIENCED DURING TWIN SCREW MIXING CAN THEN BE MEASURED BY DETERMINING THE EXTEND OF MICROCAPSULE RUPTURE AND RELEASING THE TAGGANT. TAGGANT METHODS TO BE STUDIED INCLUDE DETECTION OF RUPTURED CAPSULES BY VISUAL METHODS (COLORED DYES), HALOGEN VAPOR DETECTION (REFRIGERANT SNIFFERS), SPECTROPHOTOMETRY, ORDOR AND FLUORESCENCE. SMALL QUANTITIES OF NON-HAZARDOUS SIMULATED PBX MIXTURES CONTAINING MICROENCAPSULATED TAGGANTS WILL BE TESTED UNDER VARYING SHEAR RATE CONDITIONS IN A SMALL LABORATORY TWIN SCREW MIXER WITH INSTRUMENTATION. BY VARYING SYNTHESIS METHODS, SEVERAL MICROENCAPSULATED PARAMETERS SUCH AS CAPSULE PARTICLE SIZE/SIZE RANGE, WALL THICKNESS AND POLYMERIC ENCAPSULANT MATERIAL WILL BE STUDIED.