The Effect Of Lignin Content On The Mechanical Properties Of Densified Wood

In order to increase the utilization rate of sand shrubs and improve the performance of sand willow shrub products,based on the relationship between the lignin content of wood materials and their mechanical properties,this paper takes Salix wood and Pinus sylvestris wood as the research objects,and analyzes different wood The microscopic changes of dimensional deformation and mechanical properties of wood under compression under lignin content establish the relationship between lignin content and wood mechanical properties.First,the chemical removal test of lignin from Pinus sylvestris and Salix sylvestris with acidic sodium chlorite was used to analyze the dissolution effect of the chemical method on wood lignin,and then to analyze the influence on the cell wall structure.Secondly,high-temperature and high-pressure tests were carried out on wood samples with different lignin content after chemical treatment to analyze the influence of the size and deformation of wood with different lignin content inside the wood and the influence on its mechanical properties.Finally,the performance of the two woods before and after the test is compared to provide a research basis for future wood modification,especially the modification and efficient utilization of Salix wood.The main conclusions of this paper are summarized as follows:1.The wood of Pinus sylvestris and Salix psammophila treated with acid sodium sulfite showed that the treatment time and the concentration of glacial acetic acid had the greatest influence on the solubility of lignin in the two samples.When the time is 7 hours,the lignin content of the Pinus sylvestris sample decreased from 31.2%to 8.75%,and the lignin content of Salix psammophila decreased from the original 20.32%to 8.36%;when the addition of glacial acetic acid was 2.5m L,the lignin content of Pinus sylvestris The lignin content of the pine samples decreased from the original content to 9.23%,and the lignin content of the salix psammophila decreased from the original content to 4.83%.2.At a temperature of 100?,the two types of wood were pressed with a pressure of2MPa.After densification,the wood cell wall was compressed,the pores became smaller,and the cell wall formed a layered structure.3.After the two kinds of wood were subjected to high temperature and high pressure,the width ratio and thickness ratio of the wood sample size increased.The maximum width ratio of the Pinus sylvestris sample was 1.411,and the thickness ratio was 2.92;the maximum width ratio of the Salix psammophila sample was 1.463,and the thickness ratio was 0.394.4.The lignin content of Pinus sylvestris was about 17%,and the flexural specific strength reached the maximum value of 248.447 MPacm³·g^-1;when the lignin content of Salix psammophila was about 10%,the maximum specific strength was 381.110MPacm³·g^-1.5.The lignin content of the Mongolian pine wood sample is about 15.65%,and the tensile strength after high pressure reaches the maximum value,which is 412.563MPacm³·g^-1.The lignin content of Salix wood is about 8.25%,and its tensile strength after high pressure reaches its maximum value,which is 275.915 MPacm³·g^-1.6.When the lignin content of Pinus sylvestris wood is dissolved to 14.78%,its impact toughness reaches the maximum value,which is 5.175 J/cm².When the lignin of Salix wood is dissolved to a content of about 6.43%,its impact toughness reaches the maximum value,which is 9.733 J/cm².