Study On Physicochemical Properties Of High Temperature Heat Treated Bamboo Based On Near Infrared Spectroscopy Technology

Bamboo as a enviormental friendly material,which is characterized by fast growth and excellent mechanical properties,is more and more porpuler in the world.The effective development and utilization of bamboo resources can alleviate the tight supply of wood resources.The purpose of this study is to develop a fast and accurate model for predicting the physicochemical properties of heat-treated bamboo using near-infrared spectroscopy,and to study the chemical and crystalline properties of heat-treated bamboo from the perspective of spectral analysis.The prediction models of color and chemical composition of bamboo green side and bamboo yellow side of heat-treated bamboo were established,and the differences between these two sides of the samples and their effects on the establishment of the model were compared.In addtion,the prediction models of density and mechanical properties of heat-treated bamboo were established,and the effects of various wavelength ranges and pretreatment methods on the establishment of the model were compared.Moreover,the spectral differences between the two sides of the sample and the heat-treated bamboo at different temperatures were analyzed,and the principal component discriminant analysis was carried out respectively.Finally,the effects of heat treatment on the crystal structure of bamboo cellulose was studied from the perspective of spectral analysis.The results showed that:1)Very good prediction models of color and chemical composition of heat-treated bamboo was established.The RPD of L*model reached 11.1,the RPD of a*models was 3.54,the RPD of B*model was 7.75,the RPD of holocellulose models was 7.16,the RPD of cellulose model was 4.31,and the RPD of lignin was 10.5.Model performances of bamboo green side was better than those of bamboo yellow side.2)Good prediction models of density and mechanical properties of heat-treated bamboo was developed.The RPD of air dried density model was 2.99,the RPD of oven dried density model was 2.55,the RPD of MOE model was 2.34,and the RPD of MOE model was 1.89.The best spectral range is 7200-4000cm^-1,when compared to 12400-7200cm^-1 and 12400-4000cm^-1.3)PCA method can be used to qualitatively distinguish samples of bamboo green/yellow side and samples heat-treated at different temperatures.The characteristic absorption bands of cellulose,lignin and hemicellulose in the NIR 2^ndderivative spectral are the same as the change trend of their corresponding chemical components in bamboo,which shows the good reaction ability of NIR to the chemical properties of heat-treated bamboo.4)It is found that bamboo crystalline area becomes sparse with the increase of heat treatment temperature discoverd through the way of heavy water combined with near infrared spectroscopy,which is the reason why the mechanical properties of bamboo increase first and then decrease.The model established in this study is helpful to realize the on-line separation and detection of heat-treated bamboo.Analyses of NIR spectral are helpful to study the cellulose properties of bamboo quickly.