Effects of heat treatment on surface physicochemical properties and sorption behavior of bamboo (Phyllostachys edulis)

Abstract

• Systematically study surface physicochemical properties of 180℃ heat treated bamboo. • Reveal the mechanism of changed hygroscopicity of 180℃heat treated bamboo. • Schematic illustrate the chemical changes of heat treated bamboo at molecular level. The bamboo heat treated at 180 ℃ attracts more and more attentions for bamboo modification in industries. The effects of 180 ℃ heat treatment on surface physicochemical properties and sorption kinetic properties of bamboo were studied systematically for optimizing application. The results showed that the heat treated (HT) bamboo had much lower moisture contents both in the fast and slow process, especially at high relative humidity (RH). Meanwhile, the surface wettability was decreased and the dimensional stability was improved after heat treatment. The reduced hydrophilic OH, C = O, and C-O groups of HT bamboo caused by the degradation of polysaccharides and thermal cross-linking of lignin led to the decreased hygroscopicity. Additionally, the changed hydrogen bonding types and amorphous region of cellulose in the HT bamboo also had an effect on the water sorption behavior of cellulose. The degradation of hemicellulose and more appearance of lignin on the cell wall surface were the main reasons for the decreased water sorption behavior and improved dimensional stability of HT bamboo, which made it more suitable for applying in building and construction materials.