Bryan H. River

Fortified mangrove tannin-based plywood adhesive

Mangrove bark tannin adhesives are based on a renewable resource. They are potential substitutes or supplements for phenol–formaldehyde (PF) wood-bonding adhesives which are derived from petroleum, a finite natural resource. However, mangrove tannin adhesives exhibit poor adhesive properties including poor wet strength, brittleness, and poor wood penetration. These problems were addressed by treating tannin extract with acetic anhydride and then sodium hydroxide followed by modification with 20% resole-type PF resin. Significant structural changes occurred after the chemical treatment. Heat of reaction of tannin with formaldehyde was increased while the activation energy was drastically reduced. Premature cure was also reduced. The fortified formulations had good plywood adhesive properties.

CARBOHYDRATE MODFIED PHENOL -FORMALDEHYDE RESINS

Abstract For adhesive self-sufficiency, the wood industry needs new adhesive systems in which all or part of the petroleum-derived phenolic component is replaced by a renewable material without sacrificing high durability or ease of bonding. We tested the bonding of wood veneers, using phenolic resins in which part of the phenol-formaldehyde was replaced with carbohydrates. Our experiments show that the addition of non-reducing carbohydrates and various polyols to phenol-formaldehyde resol-resins does not adversely affect the dry- or wet-shear strength of 2-ply Douglas-fir panels bonded with the modified resins. Reducing carbohydrates, however, cannot be used as the modifier. In general, addition of about 0.6–1.0 mole of modifier per mole of phenol is optimal in the formulation of carbohydrate-or polyol-modified resin. Preliminary results show that part but not all of the modifier is chemically bound into the resin, apparently through an ether linkage. The water prehydrolysate of southern red oak wood, wh...

Relationship between Phenolic Adhesive Chemistry, Cure and Joint Performance. Part I. Effects of Base Resin Constitution and Hardener on Fracture Energy and Thermal Effects During Cure

Abstract In this study the relationships between the composition of phenol resorcinol-formaldehyde resins and paraformaldehyde concentration in the adhesive were explored, using DSC, IR, GPC, and solubility measurements. Differences of chemical composition between base resins and adhesives were compared to the fracture toughness of adhesive bonds. The cure temperature and cure time effects upon fracture toughness were also investigated. Fracture toughness tests were performed with bonded hard maple tapered double-cantilever beam cleavage specimens.

Bonding Wood Veneers with Cellulose Solvents

Abstract Various solvent systems capable of dissolving cellulose have been reported in the literature. Cuene (cupriethylene diamine hydroxide) and FeTNa (ferric sodium tartrate) are well known examples. Preliminary experiments were conducted with Cuene and FeTNa to determine if the cellulose dissolving ability of these systems could be used to bond yellow birch veneers. The results indicate that relatively high dry shear strengths, and low wet shear strengths are obtained.