The Impacts Of Irradiation Treatment And Wet Heat Treatment On Properties Of Bamboo

China is one of the countries rich in bamboo resources in the world. Bamboo contains a large amount of organic substance that attract inspects, therefore it is very important to have strict quarantine on bamboo. Irradiation treatment is low-cost, and highly efficient in that it does not need to open the package, while wet heat treatment is a pollution-free method without using any chemical. Both of these two methods are increasingly favored by the Inspection and Quarantine Department.In this paper we researched the property changes of the annual green husk bamboo (Bambusa textilis McClure) after irradiation treatment and wet heat treatment comparatively. The irradiation dose is 20 Gy,30 Gy,40 Gy,50 Gy,60 Gy,80 Gy respectively; the wet heat treatment is 56℃ 1 min,5 min,10 min,15 min,30 min respectively. We researched the main chemical composition and structure and physical-mechanical properties of the bamboo cell walls before and after treatments, and in accordance with the quarantine requirements for pest inhibitory rate of bamboo, we quantitatively evaluate the relations between the intensity of both treatments and the extent of property changes of the bamboo materials, thus providing some technical supports for both treatments. Main conclusions are as follows:(1) In accordance with the pest inhibitory rate for irradiation treatment, we found that cellulose, lignin, hemicellulose content in the cell wall was 50.91%,23.10%,64.18% respectively in 80 Gy (inhibitory rate can reach more than 99%); compared with CK(blank control group), the cellulose declined, the lignin and the heald cellulose rose. At the same time, modulus of elasticity, tangential compressive strength, shear strength, tensile strength, compressive strength was 82.54 MPa,8709 MPa,7.91 MPa,185.01 MPa,52.20 MPa respectively; Compared with CK, bamboo lightness L* value reduced 12.45%, red and green product index a* value increased 24.70%, yellow blue index b* value reduced 17.65%, and the lignin degradation made the bamboo surface darker after the gamma irradiation.(2) In accordance with the pest inhibitory rate for wet heat treatment, we found that cellulose, lignin, hemicellulose content was 50.53%,21.81%,61.11% respectively after 15 min of wet heat treatment (inhibitory rate can reach 100%); compared with CK, the cellulose and the hemicellulose declined, and the lignin rose. At the same time, modulus of elasticity, tangential compressive strength, shear strength, tensile strength, compressive strength was 163.54 MPa,14438 MPa,12.25 MPa,293.84 MPa,97.87 MPa respectively; compared with CK, the mechanical strength increased, and the materials had a tendency of brittle enhancement; compared with CK, lightness L* value reduced 3.81%, red and green product index a* value increased 13.03%, yellow blue index b* value reduced 17.50%, and the color of the materials changed little after the wet heat treatment.(3) Researching the bamboo materials by using X-ray, FT-IR,13C-NMR, SEM and AFM, and in accordance with the pest inhibitory rates, we found that in the 80 Gy of irradiation dose (or 15 min after heat and wet treatment), the chemical composition of bamboo materials and the cellulose crystallinity changed, and the structure of the materials’ surface became rougher. The preliminary degradation of cellulose, hemicellulose and lignin inside the bamboo wood materials led to the changes of both the mechanical properties and the color of the materials. Also, the irradiation treatment has stronger impacts on the properties of bamboo wood materials than the wet heat treatment.