Physical and chemical properties of Pinus massoniana synergic modified with furfuryl alcohol-caprolactam
The growing concern for environmental protection,sustainable development and biodiversity conservation has led to increased restrictions on the trade in natural high-quality wood worldwide and there are efforts to limit the amount of har-vesting to ensure the long-term health of forests and ecosystems.However,the demand for wood products is increasing and natural high-quality wood resources are decreasing.As a result,attention has been focused on how to utilize fast-growing wood species to replace traditional species.In view of the poor dimensional stability and mechanical strength of most fast-growing wood products,there is a need for a more environmentally friendly,less pollution and non-hazardous modifier like furfuryl alcohol for wood modification.Furfurylated wood has many advantages,such as excellent corrosion resistance,weather resistance,hardness,etc.However,it has drawbacks of high brittleness and poor flexural and shear resistance,which greatly limits the application range of furfurylated wood.In order to address these issues,researchers commonly use delignification and heat-pressing,as well as impregnation of flexible substances.Although the delignification and heat-pressing can effectively improve the mechanical properties of wood,one of the most popular reaction mechanisms of furfur-yl alcohol modification is the chemical cross-linking of furfuryl alcohol molecules with wood cell wall components,which reacts mainly with lignin in the cell walls of wood during the curing process.Enhancement of mechanical properties of fur-furylated wood by impregnation with flexible substances is more reasonable.In this study,the toughness of furfurylated wood was improved by adding flexible caprolactam.Caprolactam is the raw material of polyamide slice,which has strong toughness and is commonly used to prepare flexible materials such as fibers.The caprolactam and furfuryl alcohol were mixed and used to treat masson pine.The effects of synergic modification on the microstructure,element distribution,me-chanical properties and hydrophobicity of pine wood were examined by the energy dispersive spectroscopy(EDS),bending test,digital image analysis(DIC)and contact angle analysis.The EDS results showed that the synergic modification ren-dered higher degree of reaction and more polymer was distributed in the cell wall and cavity of the earlywood.The smaller tracheid and more aspirated pits of latewood hindered the penetration of modifiers,resulting in lower degree of reaction.The contact angle measurement results showed that the synergic modification greatly improved the hydrophobicity of wood.The results of mechanical test and DIC showed that the synergic modification not only improved the static bending strength and elastic modulus of the wood,but also improved its toughness.
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