Modification of waste MDF fibers with lignin and investigation of reuse of them in MDF production

MDF boards, which are one of the first products that come to mind when it comes to composite products made with wood raw materials, are widely used in the furniture industry today. Since the need for wood raw materials is increasing day by day as a result of the increase in demand for MDF boards and the advancement of production technology, factories producing wood-based boards in Turkey import wood raw materials from abroad due to raw material problems and increasing costs. Among the raw material alternatives for fiberboard production, considering its contribution to the environment the reuse of industrial wood waste and defective board waste generated during factory production is of great importance. Fiberboard manufacturers use the scrap, end-cut and inner-split boards that arise during production in their production lines by chipping them and fiberizing them together with normal wood in the digester. However, the amount of waste chips used in production is limited to 2%. Within the scope of the study, it was aimed to increase the usage rate of fibers obtained from waste fiberboards by modification of the surfaces of fibers obtained from waste fiberboards with lignin and to contribute to the reduction of imported wood raw materials. In this study; The mechanical and physical properties of fiberboards produced by modification of the fiber mixture obtained from raw wood and waste fiberboard with kraft lignin were investigated. The mechanical and physical properties of MDF boards which are produced by mixing fibers obtained from raw wood with fibers obtained from waste fiberboard in 2 different ratios of 10% and 30% and using 2 different hardeners (Ammonium chloride and HMTA) were examined. The results were compared with MDF panels which are produced using raw wood fibers. MDF boards, which are one of the first products that come to mind when it comes to composite products made with wood raw materials, are widely used in the furniture industry today. Since the need for wood raw materials is increasing day by day as a result of the increase in demand for MDF boards and the advancement of production technology, factories producing wood-based boards in Turkey import wood raw materials from abroad due to raw material problems and increasing costs. Among the raw material alternatives for fiberboard production, considering its contribution to the environment the reuse of industrial wood waste and defective board waste generated during factory production is of great importance. Fiberboard manufacturers use the scrap, end-cut and inner-split boards that arise during production in their production lines by chipping them and fiberizing them together with normal wood in the digester. However, the amount of waste chips used in production is limited to 2%. Within the scope of the study, it was aimed to increase the usage rate of fibers obtained from waste fiberboards by modification of the surfaces of fibers obtained from waste fiberboards with lignin and to contribute to the reduction of imported wood raw materials. In this study; The mechanical and physical properties of fiberboards produced by modification of the fiber mixture obtained from raw wood and waste fiberboard with kraft lignin were investigated. The mechanical and physical properties of MDF boards which are produced by mixing fibers obtained from raw wood with fibers obtained from waste fiberboard in 2 different ratios of 10% and 30% and using 2 different hardeners (Ammonium chloride and HMTA) were examined. The results were compared with MDF panels which are produced using raw wood fibers. Fiberboards were produced in a Burkle brand press with a thickness of 5 mm at 210°C temperature, 3.5 N/mm2 pressure and 210 s pressing time. The produced boards, from physical tests; Density test, sheet moisture test, 24-hour water absorption and water swelling and surface absorbency tests were performed. From mechanical tests; Bending resistance and modulus of elasticity in bending, tensile strength perpendicular to the board surface and surface durability tests were carried out according to TSE EN standards. Statistical analysis was performed on the produced boards in the SPSS program, and thermal analysis was performed on the fiber mixture obtained from waste fiberboard and raw wood. According to the test results; Although the increase in the use of fiber obtained from waste fiberboard negatively affected the swelling, water absorption and strength properties of the produced fiberboards, the mechanical and physical properties of the fiberboard improved with the modification of fibers using lignin. Vertical tensile strength of fibreboards produced by modifying the fiber mixture obtained from raw wood with 5% and 7.5% lignin by weight, according to the fully dry fiber ratio of the fiber mixture obtained from waste fiberboard at a rate of 10%. Fiber produced with 100% raw pine wood fibers without modification with lignin It was found to be higher than the fiberboards. Formaldehyde emission of fiberboards increased with increasing fiber content obtained from waste fiberboard. Modification of fibers with lignin was observed to reduce the formaldehyde emission of MDF produced with fibers obtained from waste fiberboards. It was observed that the use of fibers obtained from waste fiberboard reduced the mechanical properties of MDF, while modification of the fibers with 5% and 7.5% kraft lignin by weight improved the mechanical properties of MDF. It was determined that water resistance increased and formaldehyde emission value decreased by modification of fibers with lignin. It was observed that HMTA was not compatible as a hardener in the production of fibers modified with lignin in the MDF process. According to the results; In MDF production, using ammonium chloride hardener and modifying the mixture of 10% waste MDF fibers with raw wood fibers with 5% and 7.5% lignin by weight gives better results than boards produced from 100% raw wood. Modification of fibers with lignin allows the use of waste MDF fiber in MDF production to increase to 10%.