Thermal and Gluing Properties of Phenol-Based Resin with Lignin for Potential Application in Structural Composites

Abstract

Using Kraft lignin, bio-based adhesives have been increasingly studied to replace those petrochemical-based solutions, due to low cost, easy availability and the potential for biodegradability of this biomaterial. In this study, lignin-based phenol-formaldehyde (LPF) resins were synthesized using commercial Eucalypt Kraft Lignin (EKL), purified at 95%, as a phenol substitute in different proportions of 10%, 20%, 30% and 50%. The properties of bio-based phenol formaldehyde (BPF) synthesized resin were compared with phenol-formaldehyde resin (PF) used for control sampling. The results indicated that viscosity, gel time and solid contents increased with the addition of pure EKL. The shear strength test of glue line was studied according to American Society for Testing and Materials (ASTM), and BPF-based results were superior to samples bonded with the PF as a control sample, being suitable for structural purposes. Changes in the curing behavior of different resins were analyzed by Differential Scanning Calorimetry (DSC), and sample comparison indicated that the curing of the LPF resin occurred at lower temperatures than the PF. The addition of EKL in PF reduced its thermal stability compared to traditional resin formulation, resulting in a lower decomposition temperature and a smaller amount of carbonaceous residues.

Properties of Bark Particleboard Bonded with Demethylated Lignin Adhesives Derived from <i>Leucaena leucocephala</i> Bark

“…The demethylation process improves the adhesive properties of lignin, making it suitable for bonding various materials in composite production. These adhesives exhibit good compatibility with other bio-based materials, enhancing the sustainability of composite materials [43]. They also contribute to the enhancement of mechanical properties in composites, such as strength and stiffness [44].…”

Influence of Pressing Temperatures on Physical–Mechanical Properties of Wood Particleboards Made with Urea-Formaldehyde Adhesive Containing Al2O3 and CuO Nanoparticles

“…Therefore, it is important to understand that the performance of a wood composite is directly related to the polymerization of the adhesive, which can depend on variables such as pressing time and temperature [ 3 , 5 , 6 , 7 ].…”

Incorporation of Lignin in Bio-Based Resins for Potential Application in Fiber–Polymer Composites

“…Through the biorefining of lignin, valuable aromatic structures akin to phenol can be obtained; however, the depolymerization processes required to achieve this are costly [9,13], which explains why this natural polymer has been mostly incorporated into resins, adhesives, foams, and other polymeric materials in its macromolecular form [14][15][16][17][18][19]. In fact, several efforts have been made in recent years to incorporate lignin into the polymer structures of phenolic [20][21][22], polyurethane [23], furanic [24], epoxy [25][26][27], polyester [28][29][30], vinyl ester [30,31], and acrylate-based [32,33] resins.…”