Enhancing environmental performance of formaldehyde-based adhesive in lignocellulosic composites - Part II

Purpose - To investigate a new approach for the prevention of lignocellulosic composites based on agro-fibres (e.g. sugar-cane bagasse) from the emission of toxic formaldehyde. Design/methodology/approach - Five organic polymer containing nitrogen-urea formaldehyde (UF) adhesive systems were used as bonding agents for bagasse fibres. The environmental performance of the lignocellulosic composites prepared were evaluated in terms of the effect of the organic polymers on the percentage of free formaldehyde in the adhesive system and the adhesion properties (static bending and water resistance properties) of the composite produced, in comparison with that prepared from un-modified UF. The nitrogen content of the polymer and the amount of organic polymers incorporated in the adhesive system were optimised using the 3D response surface methodology and the multi-linear regression technique. Findings - All investigated organic polymers (crude PAM-g-starch, PAM-g-starch, PAM, CE-starch and Cm-starch) were found to enhance the performance of the UF-adhesive for producing environmentally friendly bagasse-composite, whereas the reduction of free-HCHO in UF-adhesive systems ranges from 26 to 100 percent. The performance of the composite produced exceeded the ANSI requirements for Grade H-3 particle-board. Research limitations/implications - Despite the success in improving the performance (mechanical properties and reduction of free-formaldehyde) of the UF-adhesive and agro-composites, the polymers needed to be incorporated at a high percentage (12-20 percent) resulting in reduced water resistance of the product. Further investigation is needed to resolve this problem. Practical implications - The approach developed provided a simple and practical solution to enhancing the performance of waste agro-fibres and commercial amino adhesive in the production of high performance lignocellulosic composite. Originality/value - The organic polymers UF adhesive systems are novel bonding agents for agro-fibres and could be used in timber mills for production of particle-board and medium density fibre-board.