Prediction Of Wood Species And Ageing Performance Of The Changchun Palace Based On NIR

The wood species and ageing performance of the load-bearing wood structural components of the Changchun Palace,the Palace Museum were researched in this study.On the basis of wood identification,the ageing performance of wood structural components were studied and the predicting models of wood species and their ageing performance constructed by using NIR spectroscopy technology were discussed.Firstly,the wood species collected from wood structural components in the Changchun Palace were discriminated by means of traditional wood identification.Secondly,the aging performance of wood construction was studied by investigating chemical components,XRD,DTG and FTIR of wood samples collected from inside and the outside of the main hall of the Changchun Palace.The ageing degree and ageing cause of different decaying samples of the Changchun Palace were analyzed.Thirdly,NIR information of the samples with different aging degree was collected.On the basis of chemical components analysis the content of wood samples used as a marker.Combined with chemometrics and by means of standardization and factorization methods,the models of species and aging prediction of wood construction were established.Finally,the feasibility of the established prediction models of wood species and aging were evaluated.The following conclusions can be drawn:(1)The results discrimination of wood species showed that there were three main types of wood used in the Changchun Palace,Larix gmelinii,Pinus sylvestris and Phoebe zhennan.(2)The ageing performance analysis showed that the cellulose,hemicellulose and lignin were degraded.The absorption peak of the lignin benzene ring skeleton of A2 was detected in 1510cm-1,and at1732cm-1.The tensile characteristic peak of C=O in the acetyl and carboxyl groups of hemicellulose disappeared measured by FTIR.Then we concluded that the visiable-ultraviolet light irradiation was main reason of wood construction ageing of the Changchun Palace.(3)By measuring the content of 1%NaOH extractives of wood construction samples with different ageing levels.Found that the ageing degree of the wood structure was linearly correlated with the content of 1%NaOH extractives.We concluded that with the increase of aging degree of wood,1%NaOH extractives content also increased.The 1%NaOH extractives content can be used as a quantitative evaluation index of wood ageing degree.(4)The qualitative prediction model of wood species of the Changchun Palace was established by the factorization method.Also a quantitative prediction model of the ageing degree of the Changchun Palace was established by the PLS method which was stable and reliable by parameter evaluation.The conclusion showed it was feasible to predict and evaluate wood species and the ageing properties of the Changchun Palace by establishing prediction models.