The three samples tested in this work included handsheets with out coating, samples coated with the composites at two fiber/PLA ratios (i.e., PLA95and PLA99). As addressed previously, at constant temperature and RH (%), a steady state will be reached where WVTR values were calculated from the slope of sample weight change versus time. Various samples with different changing trends for temperature changed from 23 to 38◦C are marked in Fig. 7 and the slope for each sample is shown in Fig. 8a and b. For the control sample, when tested at 23◦C (Fig. 8a), the sample weight changed from original 120.8–116.6 mg in the duration from 0.5 s to 60.9 min,and the slop of weight change versus time came to 0.0704. For the testing period at 38◦C starting from 90.1 min to 155.7 min in Fig. 8b,the sample weight changed from 109.3 to 97.5 mg with the slope of 0.183, which is much higher than that of at 23◦C. Similar results were obtained for the composite-coated paper. For PLA99, the two slopes at 23 and 38◦C were 0.0259 and 0.0819. For PLA95, the two slopes at 23 and 38◦C were 0.0543 and 0.170, respectively. The results showed that there was significant higher water vapor trans-fer ratio induced by the higher temperature at 38◦C compared to 23◦C. The results also proved that the WVTR is indeed sensitive to the testing temperature.