Effect of sodium lignosulfonate on bonding strength and chemical structure of a lignosulfonate/chitosan-glutaraldehyde medium-density fiberboard adhesive

Studies on the manufacture of medium density fiberboard (MDF) from oil palm frond (OPF) fibre were conducted to provide a sustainable and feasible source of lignocellulosic materials. The quality and properties of the fibre are very important as it dictates the final MDF properties. The properties of fibre like fibre pH, buffering capacity, and morphology can influence most of the MDF performances. Refining condition is one of the most important factors which determine the properties of the refined fibre. In this study, the effects of different refining pressures and temperatures on OPF fibre were evaluated. The refining of OPF fibre was observed at four levels of refining parameters; which were categorized as low (2 bar at 130 °C), medium (4 bar at 150 °C), high (6 bar at 170 °C), and severe (8 bar at 190 °C). The refining heating time of 5 minutes was employed. The pH, buffering capacity, morphology, and the surface of the fibres were evaluated. The refined fibres were used to manufacture fibreboard panels at a target density of 720 kg/m3 and 12% urea formaldehyde (UF) resin. The panel's physical (thickness swelling) and mechanical properties (bending and internal bonding strength) were then evaluated according to European Standard (EN 622-5, 2006). The results indicated that refining conditions affected the properties of the fibres and final boards. High steam pressure and temperature-induced pH changes in OPF fibres, leading to more acidic fibres and greater acid buffering capacity. The fibre separation was more adequate at this level and produced fibre with a smooth surface. Based on the test results for fibreboard properties, high steam pressure and temperature produced better dimensional stability of panels and bending and bonding strength. However, at the highest refining condition (severe level), the board performances began to deteriorate. The best performances of the samples were found for the panels made under refining conditions of 6 bar at 170 °C.

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Synthesis Mechanism of an Environment-Friendly Sodium Lignosulfonate/Chitosan Medium-Density Fiberboard Adhesive and Response of Bonding Performance to Synthesis Mechanism

Materials ◽

10.3390/ma13245697 ◽

2020 ◽

Vol 13 (24) ◽

pp. 5697

Author(s):

Xiaodi Ji ◽

Minghui Guo ◽

Li Zhu ◽

Wenxin Du ◽

Hongbin Wang

Keyword(s):

Medium Density Fiberboard ◽

Hydroxyl Groups ◽

Medium Density ◽

Amino Groups ◽

Sodium Lignosulfonate ◽

Synthesis Mechanism ◽

Environment Friendly ◽

Bonding Performance ◽

3D Network ◽

Mass Ratios

Environment-friendly medium-density fiberboards (MDFs) prepared using sodium lignosulfonate/chitosan adhesives (L/C) show potential in environment-friendly wood-based panel application. However, the synthesis mechanism of this adhesive and the relationships between synthesis mechanism and bonding performance were not discussed in depth. Herein, the synthesis mechanism of L/C was explored in detail based on characterizations of L/C with different mass ratios of sodium lignosulfonate to chitosan by Fourier-transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction. For L/C with different mass ratios of sodium lignosulfonate to chitosan, the corresponding bonding performance was also determined based on characterizations of mechanical and dimensional performance of MDFs. Results showed a 3D network structure of L/C formed through the hydrogen linkages among hydroxyl groups in sodium lignosulfonate and hydroxyl and amino groups in chitosan, amide linkages resulted from reaction between carbonyl groups in sodium lignosulfonate and amino groups in chitosan, and sulfonamide linkages originated from reaction between sulfonic groups in sodium lignosulfonate and amino groups in chitosan. The mechanical performance of MDF was closely related to the 3D network and amino groups of L/C, while the dimensional performance of MDF was negatively affected by sodium lignosulfonate. The MDFs with 1:3 and 1:2 mass ratios of sodium lignosulfonate to chitosan showed superior mechanical properties and comparable dimensional performance with a commercial panel.

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Preparation and characterizations of a chitosan-based medium-density fiberboard adhesive with high bonding strength and water resistance

Carbohydrate Polymers ◽

10.1016/j.carbpol.2017.08.100 ◽

2017 ◽

Vol 176 ◽

pp. 273-280 ◽

Cited By ~ 27

Author(s):

Xiaodi Ji ◽

Bin Li ◽

Bingnan Yuan ◽

Minghui Guo

Keyword(s):

Bonding Strength ◽

Water Resistance ◽

Medium Density Fiberboard ◽

Medium Density ◽

High Bonding Strength

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Calcium carbonate modified urea–formaldehyde resin adhesive for strength enhanced medium density fiberboard production

RSC Advances ◽

10.1039/d1ra04316a ◽

2021 ◽

Vol 11 (40) ◽

pp. 25010-25017

Author(s):

Li Lu ◽

Yan Wang ◽

Tianhua Li ◽

Supeng Wang ◽

Shoulu Yang ◽

...

Keyword(s):

Calcium Carbonate ◽

Urea Formaldehyde ◽

Medium Density Fiberboard ◽

Urea Formaldehyde Resin ◽

Formaldehyde Resin ◽

Medium Density ◽

Ionic Bond ◽

Resin Adhesive ◽

Uf Resin ◽

Modified Urea

Reactions between CaCO3 and CH2O2 during polycondensation of UF resin produce Ca2+. Ionic bond complexation binds Ca2+ with UF resin. The UF resin crystalline percentage decreases from 26.86% to 22.71%. IB strength of resin bonded fiberboard increases from 0.75 to 0.94 MPa.

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