Influence of fungal infection on the long-term water absorption and morphological behavior of bagasse fiber/polypropylene composites at different exposure times

In this study, the effect of fungal decay on the long-term water absorption of bagasse fiber/polypropylene composites at different exposure times was studied. For this purpose, the blend composites were prepared through the melt mixing of bagasse fiber with polypropylene at 40: 60% weight ratios, with 2% coupling agent for all formulations. Then, the samples were exposed to brown-rot (Coniophora puteana) and white-rot (Trametes versicolor) fungal treatments for 8, 12 and 16 weeks with the Kolle flask method. The long-term water absorptions of samples were evaluated by immersing them in water at room temperature for several weeks, and water diffusion coefficients were also calculated by evaluating the water absorption isotherms. Also, the morphology of composites was characterized using scanning electron microscopy (SEM). The results showed that the water absorption of samples was actually much higher after both types of rotting and was significantly higher than that of control samples. Also, the water absorption of white-rotted samples was higher than that of brown-rotted and control samples for all weeks of fungal exposure times. In addition, the control sample and composite after 16 weeks of exposure to white-rot fungi exhibited the lowest and highest water diffusion coefficients, respectively. The mechanism of water absorption of samples against fungal decay at different exposure times followed the kinetics of a Fickian diffusion process. Furthermore, the SEM micrographs showed that the extent of degradation increased with increasing exposure time to fungus.