wood-frp adhesion 1-9-08

wood-frp adhesion 1-9-08 - Adhesion Between Wood and Fiber...

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1 Adhesion Between Wood and Fiber Reinforced Polymers: Bonding Issues Douglas J. Gardner , Professor of Wood Science Roberto Lopez-Anido, Associate Professor of Civil Engineering University of Maine Advanced Engineered Wood Composites Center Outline • Adhesive Bonding • Bond durability • HMR Coupling Agent • Performance-Based Material Evaluation Methodology
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2 Adhesion Bonding Mechanisms • Mechanical Interlocking • Adsorption and Surface Reaction • Electrostatic • Interdiffusion spreading θ penetration spreading Wood Bonding Considerations • Wood is a porous material • Wood is also an anisotropic material • Wood surface chemistry is heterogeneous • Wood swells and shrinks as a function of moisture content SEM - Softwood SEM -Hardwood
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3 Wood Hygroscopicity • Dry wood contains 5-12% moisture depending on source and local environment Monomolecular layer of water on wood at ~ 6% moisture content. FRP Bonding Considerations • FRP plates are non porous (exceptions) • Adhesion relies primarily on chemical bonding • FRP does not change dimensions as a result of water immersion compared to wood (non swelling/shrinking) • Surface preparation is important – Mechanical – Chemical (priming)
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4 Pertinent Adhesive Bonding Mechanisms for Wood-FRP • Mechanical Interlocking • Chemical Bonding – Covalent – Acid-base – Hydrogen Bonding – Lifshitz- van der Waals FRP-Wood Bonding Critical Issues • Type of reinforcement (E-glass or carbon) • Durable & cost-effective adhesives • Feasible procedure for surface priming & adhesive curing • Efficient plate bonding or fabric wet out process • Effect of wood preservative chemicals & treatment on FRP properties • Environmental exposure combined with loading (synergistic effects)
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5 Wood Reinforcement Methods • Hand Lay-up (Wet Preg) • Resin Infusion (SCRIMP) • Continuous Lamination Sheets –Dow Fu lc rum – Gordon glass and carbon – TwinTex-polypropylene-glass • Pultruded plates – Phenolic-glass – Vinylester-glass – Polyurethane-glass • Carbon fiber-phenolic composite sheet – Japanese development (Toho Rayon) Hand Lay-up • Simplest and most widely used manufacturing process for FRPs • Good for repair and special projects • Adequate research tool • May not be practical for commodity-based wood- FRP processes
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6 Vacuum Bagging • Allows for the production of large, high quality, relatively low cost composite parts. • Very versatile manufacturing method • Worker skill is important to part quality Seaman Composite Resin Infusion Molding Process SCRIMP • Patent currently held by TPI Composites • Hybrid of RTM, VARI and vacuum bagging. • Injection is usually achieved through the use of a high-permeability surface layer to cause through-the-thickness flow.
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This note was uploaded on 12/21/2010 for the course AEWC 430 taught by Professor Dg during the Fall '08 term at University of Maine Orono .

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wood-frp adhesion 1-9-08 - Adhesion Between Wood and Fiber...

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