2. Experimental
The A and B materials in this study were low-density polyethylene
(LDPE) and the copolymer ethylene acrylic acid (EAA) in a
1:1 composition for all films. The film materials were produced in
pilot scale at Tetra Pak, Lund, Sweden via hot-melt extrusion. The
films consisted of either the pure materials LDPE or EAA or different
layered combinations as shown in Fig. 1. Regardless of the
number of layers, the total thickness of all films was kept constant
at 10072 mm. To guarantee homogeneity of the film materials,
samples were taken at different areas of the films. The cross-section
was also studied by a microscope (Olympus BH2 polarizing
microscope) prior to measurements.