Layer multiplying die for generating interfacial surfaces

A method for generating interfacial surfaces within a first composite stream comprised of discrete overlapping layers of polymeric material, a pair of such discrete overlapping layers defining a generally planar layer interface therebetween which lies generally in an x-z plane of an x-y-z coordinate system, wherein the z-axis extends in the general direction of flow of the first composite stream, the x-axis extends transversely of the first composite stream and defines a width dimension of the first composite stream and the pair of discrete overlapping layers, and the y-axis extends perpendicularly away from the planar layer interface and defines a thickness dimension of the first composite stream and the pair of discrete overlapping layers, the method comprising the steps of:

• (i) dividing the first composite stream into a plurality of branch streams along the x-axis such that the pair of discrete overlapping layers and the generally planar layer interface defined therebetween are distributed among at least two of the branch streams;
• (ii) within each individual branch stream of the at least two branch streams, expanding the width dimension of the branch stream along the x-axis and simultaneously contracting the thickness dimension of the branch stream along the y-axis;
• and
• (iii) recombining the branch streams, after simultaneously expanding and contracting each of the at least two branch streams, in an overlapping relationship to form a second composite stream which comprises a greater number of discrete overlapping layers of polymeric material than the first composite stream.