Measuring the Adhesive Bond Quality of Vinyl Ester-Glass Composites on Novolak HMR Treated Wood

The objectives of this research were to 1) reduce the drying time of novolak-based HMR coupling agent, 2) reinforce wood samples with E-glasslvinyl ester resin composite using the SCRIMPThq process, 3) evaluate the durability and strength properties of the FRP-wood composites, and 4) evaluate the bonding strength of wood-to-wood bonding using vinyl ester resin. To reduce the drying time of HMR-treated wood laminates, a randomized complete three factorial experiment was used to evaluate five HMR drying times, two HMR spread rates, and two HMR solids contents. The experiment evaluated the sensitivity of the HMR treatment process to accelerated drying. The analysis resulted in the reduction of the HMR drying time to 15-20 minutes instead of the 18-24 hours usually required for epoxy resin bonded hard maple laminates. The HMR treatment process is not sensitive to changes in the HMR spread rate or the HMR solids content, but is significantly effected by the HMR drying time. The accelerated drying of HMR was applied to wood samples reinforced with Eglasslvinyl ester resin using the SCRIMPTM process. A technique was developed to apply the SCRIMPTM process for the reinforcement of small scale wood members such as glulam billets and boards. These samples were evaluated with typical screening tests ASTM D 905 standard test method for strength properties of adhesive bonds in shear by compression loading and the ASTM D 2559 standard specification for adhesives for structural laminated wood products for use under exterior (wet use) exposure conditions. The analysis resulted in the reduction of the total production time of wood-FRP composites by 18-24 hours. The FRP-wood composites had a high shear strength and a high percentage of wood failure. Wood-to-wood bonding using vinyl ester resin was not successful. Typical bonding parameters such as clamping pressure, spread rate, opening time, etc. had no effect on the bonding performance of wood-to-wood vinyl ester bonded laminates. The vinyl ester resins used failed most of the bonding tests. It is recommended to evaluate vinyl ester resins that are specifically promoted for wood-to-wood bonding