| Abstract: | Peeling of polyimide coatings bonded to aluminum substrates was analyzed from a thermodynamic perspective with the intent of determining how the energy expended in separating the bonded materials is consumed. The mechanical work expended and the heat dissipated during peeling were simultaneously measured using deformation calorimetry. The surfaces exposed by peeling were analyzed by electron microscopy and electron spectroscopy. The thermodynamics of tensile drawing for polyimide were studied using deformation calorimetry and thermomechanical analysis. When polyimide coatings were peeled from aluminum substrates at a peel angle of 180°, almost all of the mechanical energy was consumed in propagating the bend through the coating being peeled. The fraction 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 polyimide. When the bend is propagated through aluminum, which has a limited capacity to store latent internal energy, 97-100% of the mechanical energy is dissipated as heat. |
