Abstract: Heat sealable polymeric films having an outer, polymeric heat seal layer with a viscosity at its heat sealing temperatures such that it will flow into interstitial spaces between the fibers of a fibrous material and encapsulate the fibers at such temperatures, an intermediate polymeric layer in contact with the heat seal layer, the intermediate polymeric layer being capable of cohesively splitting when the heat sealed film is peeled, and at least one further polymeric layer, the heat seal layer being easier to fracture than the intermediate layer at the temperature at which peeling is to be effected so that heat seal layer ruptures rather than peeling continuing through the intermediate layer once peeling has been effected through the heat sealed zone.