AN EXPERIMENTAL PARTITIONING OF THE MECHANICAL ENERGY EXPENDED DURINGPEEL TESTING

Peeling of polyimide coatings bonded to aluminum substrates was analyz ed from a thermodynamic perspective with the intent of determining how the energy expended in separating the bonded materials is consumed. T he mechanical work expended and the heat dissipated during peeling wer e simultaneously measured using deformation calorimetry. The surfaces exposed by peeling were analyzed by electron microscopy and electron s pectroscopy. The thermodynamics of tensile drawing for polyimide were studied using deformation calorimetry and thermomechanical analysis. W hen polyimide coatings were peeled from aluminum substrates at a peel angle of 180-degrees, almost all of the mechanical energy was consumed in propagating the bend through the coating being peeled. The fractio n of peel energy dissipated as heat was 48 +/- 1.3% and nearly all of the remainder was stored as latent internal energy in the peeled polyi mide. When the bend is propagated through aluminum, which has a limite d capacity to store latent internal energy, 97-100% of the mechanical energy is dissipated as heat.