.Specimens used for the water absorption tests were cut from 24-ply all-PP laminates (processed at both 0.1 and 4 MPa) with dimensions in accordance with ASTM D570 (77 × 25 × 3.2 mm). For comparison, GMT and NMT composites and samples of a ethylene–propylene copolymer (as was used to provide the skin layer of the tapes during co-extrusion [32]) were also tested. At least three specimens of each material were tested. All specimens were dried in an oven for 24 h at 60 °C and weighed before immersion in a distilled water bath at different temperatures; 23 °C (room temperature), 40 °C and 65 °C. The specimens were periodically removed from the water bath, wiped free of surface moisture, immediately weighed to the nearest 1 mg using a Mettler AE200 balance and then replaced into the water bath.