The structure of the flexible Ca-test cell.
The test sample structure: the Al2O3 inorganic layer is deposited by the use of a RF-magnetron sputtering system. Sample 1 has an Al2O3 barrier coated PES deposited on one side; Sample 2 has an Al2O3 barrier coated PES deposited on both the upper and lower sides. The scanning electron microscope image of the Al2O3 layer is presented on the right side of the figure.
The actual WVTR measurements on Sample 1. We compare the measurement time for the conventional Ca-test and the flexible Ca-test.
The comparison of the measured data performed by the flexible Ca-test and the optical Ca-test. The left y-axis represents the normalized current related to the flexible Ca-test. The right y-axis represents the transmittance related to the optical Ca-test.
(a) Change in transmittance with wavelength and time. The upper two graphs show the bare substrate transmittance, which is just an Al2O3 coated single layer and two overlapped Al2O3 coated single layers, respectively. As the time increases the transmittance increases, caused by the calcium oxide formation. (b) Pictures of the calcium degradation over time; the center calcium is totally oxidized after 100 min, the cell is then seen as transparent.
(a) The comparison of the WVTR curve without bending stress and with bending stress on Sample 1. (b) The comparison of the WVTR curve without bending stress and with bending stress on Sample 2. (c) The bending stress is applied to the flexible Ca-test cell. Each trial is repeated up to 500 times. In this test we found seriously degraded barrier properties.
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