2.6.2. Water Vapor Permeability (WVP)

Water vapor permeability (WVP) was measured according to ASTM E96/E96M-16 (2016) using a PERME™ W3/030 automatic water vapor permeability tester (Labthink Instruments Co., Ltd., Jinan, China). Films were cut into round specimens (80 mm in diameter) with a special sampler. The test was performed at 38.0 ◦C and 90% RH (relative humidity) with a preheating time of 4 h and a weighing interval of 120 min. The WVP of each sample was obtained from the average of three measurements.
