Moisture absorption and hydrothermal aging in bamboo fibre/polyester composite

Moisture absorption and hydrothermal aging in bamboo fibre/polyester composite

Outdoor application of natural fibre reinforced composites is restricted mainly due to its capability to absorb moisture which can lead to physical and mechanical degradation. In this work, bamboo fibre/polyester composites subjected to alkalization at 0, 4, 6, and 8 wt.% of sodium hydroxide (NaOH), as well as neat polyester, were immersed in water at room temperature (25ºC) for 60 days and at 80ºC for two days.
The percentages of weight and thickness increment were recorded until a plateau was observed on the moisture absorption and thickness swelling graphs, or obvious physical degradation was observed on the specimens. At room temperature, all specimens reached equilibrium moisture content and maximum thickness swelling at 60 days, with 6 wt.% NaOH treated composites exhibiting the least absorptivity and swelling. Untreated composites (0 wt.%) experienced the highest percentage of weight gain indicating that alkalization reduces moisture absorption of composites. At 80oC, there was no significant difference on the rate of weight gain among the treated composites but all specimens showed signs of physical degradation on the second day with maximum thickness swelling achieved.