Abstract:

Objective: In this paper, Robinia pseudoacacia was taken as the research object, and the physical and mechanical properties such as density, compression strength parallel to grain, bending strength and bending modulus of elasticity of branches, stems and roots of R. pseudoacacia at different ages were studied. We used the SEM image and chemical composition to explain the intensity difference of branches, stems and roots wood in order to enhance the added value and to provide theoretical supports and experimental bases for improving the comprehensive utilization rate of branches, stems and roots. Method: The physical and mechanical properties such as density, compression strength parallel to grain, bending strength and bending modulus of elasticity of branches, stems and roots of R. pseudoacacia at different ages were determined, as well as the SEM images and chemical composition. Result: The air-dry density of R. pseudoacacia in one tree was classified as branches > stems > roots. With the increase of age, the density of branches, stems and roots increased, but the extent of increase was small. The air-dry density of the branches of R. pseudoacacia was slightly higher than medium density, and the air-dry density of stems and roots was medium density. The compression strength parallel to grain, bending strength and bending modulus of elasticity in one tree were all classified as stems > branches > roots. With the increase of tree age, the compression strength parallel to grain, bending strength and bending modulus of elasticity of branches, stems and roots of R. pseudoacacia increased, but the extent of increase was small. There was a positive correlation between cellulose content and mechanical strength, and lignin content was negatively correlated with mechanical strength. The content of cellulose in roots was larger than that in branches and stems. Conclusion: The stems of R. pseudoacacia above 10 years old can be used as timber structure of load-bearing wood; the mechanical strength of the branches is slightly lower than that of the stems, it can be used as a general structural material in the case of meeting the requirements of the size of the timber; the roots can be used as a small size decorative structural material. Roots of R. pseudoacacia has a high content of cellulose, which can be used to make medium density fiberboard.

Key words: Robinia pseudoacacia, branches, stems, roots, density, strength