A method for improving adhesion between two adjacent layers of a laminate membrane includes annealing the laminate membrane at a temperature between an α-transition temperature and a β-transition temperature of at least one polymeric component of at least one of two adjacent layers for a time sufficient for the at least one polymeric component of at least one of the adjacent layers to partially diffuse into the other adjacent layer. A sealed, inflated bladder of the invention prepared from the laminate membrane can experience high strains without layer separation or peeling of the laminate layers, even at a seam.