Study on the Effect of Two-Step Saturated Steam Heat Treatment Process on the Properties of Reconstituted Bamboo

With the aim of utilizing reconstituted bamboo as a carbon cycle-oriented material, the improvement of physical and mechanical properties has been actively studied to solve using problems. The saturated steam heat treatment process has been widely used in worldwide. With the development and exploration of this technology, two-step saturated steam heat treatment process appears in some practical production, that is, after a period of saturated steam heat treatment at a lower temperature, the bamboo bundles are taken out and seasoned for a period of time, and then put back into the heat tank again, and heated at a higher temperature for another period of time. During the two-step saturated steam heat treatment, the physical and mechanical properties of bamboo changed. However, the mechanism of two-step saturated steam heat treatment has not been thoroughly discussed. For purpose that this paper all discuss and find out the mechanism of two-step saturated steam heat treatment on the change of physical and mechanical properties of reconstituted bamboo. In this work, the one and two-step saturated steam heat treatments were carried out according to the actual production parameters, and the physical and mechanical properties of the reconstituted bamboo board made of treated bamboo bundles were analyzed, including the color change, the thickness swelling (TS), modulus of elasticity (MOE), modulus of rupture (MOR) and shear strength. The results indicate that two-step saturated steam heat treatment is better than one-step. Based on the detailed study of the chemical composition, crystallinity and micro-morphological characteristics of the heated bamboo bundles, it is further revealed that during two-step saturated steam heat treatment, oxygen air is added to the reaction system between the two heat treatment processes to further catalyze the oxidation of hemicellulose and enhance the crystallinity of cellulose, so as to improve the properties of the final products. Our work has optimized the saturated steam heat treatment process which is widely used in industry, pointing out a new idea in the experimental and theoretical basis for the development of recombinant bamboo manufacturing industry.