Measurements of water absorption and thickness swelling were made according to ASTM D 570 on the specimens used for tensile testing, after vacuum-drying at 70 C and stabilization in a desiccator.
Each specimen was immersed in distilled water, at ambient temperature, in falcon tubes of 14 ml for different time periods
(up to 15 days).
At the end of each period, five specimens of each condition were gently blotted with absorbent paper to remove
the excess water on the surface, immediately reweighed and their thickness measured using a digital micrometre from Mitutoyo (Japan) (±0.001 mm), and then re-immersed.
Water absorption (WA) was calculated as