Characteristics and Bond Performance of Wood Adhesive Made from Natural Rubber Latex and Alkaline Pretreatment Lignin

The aim of this study was to characterize an aqueous polymer isocyanate (API) type adhesive made from natural rubber latex (NRL) and lignin as base polymers, and to evaluate bond performance of the adhesive as laminated wood adhesive. The base polymers of the adhesive were prepared by blending NRL, polyvinyl alcohol (PVA), and lignin isolated from black liquor of alkaline pretreatment of oil palm empty fruit bunch (OPEFB) and sugarcane bagasse (SB) with compositions of 25/25/0, 25/20/5, 25/15/10, 25/10/15, 25/5/20, and 25/0/25 (w/w/w). The isocyanate crosslinker was added at the level of 15% of the weight of base polymer. The glass transition temperature (Tg), heat degradation, and the homogenity of the adhesive blend were analyzed. The adhesive was used for producing laminated wood (20×8 cm²). Results showed that the addition of lignin in the base polymer blends of API adhesive did not significantly affect the Tg of the adhesives. However, it affected the thermal decomposition and bond performance of the adhesives. There were more residues and less homogenous adhesive solution due to the addition of lignin in the base polyemr blends of API adhesives. The addition of lignin in the base polymer blends caused significant decrease in bond performance of the adhesive applied in glue laminated wood.