EFFECTS OF SILANE COUPLING AGENTS ON INTERNAL REINFORCEMENT OF WOOD BY E-GLASS AND BASALT FIBERS

The internal reinforcement of Douglas-fir by glass or basalt fibers im pregnated with resorcinolphenol-formaldehyde or polymeric diphenylmeth anediisocyanate bonding resins has been investigated. The objective wa s to evaluate the improvement in composite properties by the use of si lane coupling agents. Fibers were treated with 3-(4-methoxyphenyl) pro pyl methyldichlorosilane for use with the phenolic resin, and with 3-a minopropyl triethoxysilane for use with the isocyanate resin. Resin im pregnated fiber plies were sandwiched between wood pieces to prepare t est specimens with 17 vol. % fiber for measurement of block shear stre ngth, and modulus of rupture (MOR) and modulus of elasticity (MOE) in 3-point bending, and interlaminar shear strength in 5-point bending. T he durability under wet conditions was evaluated by subjecting the spe cimens to an accelerated exposure test (ASTM D2559). It was found that silane application resulted in slight shear strength improvement unde r dry conditions but much higher increase in shear strength retention after exposure to moisture. Basalt fibers and E-glass fibers gave simi lar results and comparable properties.