Thesis
Characterization of PF/PVAC hybrid adhesive-wood interaction and its effect on wood strand composites performance
Washington State University
Master of Science (MS), Washington State University
2010
Handle:
https://hdl.handle.net/2376/103001
Abstract
A multifunctional hybrid adhesive system developed for profiled composite manufacturing was examined in this study. A binary adhesive system, phenol formaldehyde (PF)/ polyvinyl acetate (PVAc), offers initial adhesion to improve wood-strand mat handling during the first stage of composite processing, after which a durable bond is achieved through curing of PF resin under heat and pressure. Before effectively applying this adhesive, it is important to understand adhesive-wood interaction at different scales. This thesis evaluated the physical properties of PF and PVAc resin blend as individual resin proportions were varied, and then characterized the interactions between the PF/PVAc hybrid adhesive and the wood substrate by evaluating bond strength at macro-scale, and gross adhesive penetration at micro-scale in sugar maple (tangential and radial surfaces). The bond performance and adhesive penetration of PF/PVAc were found to be comparable with that of neat PF when PVAc content was less than 50% in the resin blend, while they underwent an obvious deterioration when PVAc content rose beyond 50%. Results regarding wood strand composite performance using a response surface model indicate that addition of PVAc does not significantly affect MOE. However, PVAc content has a positive effect on MOR, IB under normal conditions, water absorption and thickness swelling; whereas, under changing environmental conditions, increase in PVAc content beyond optimum ratio has a negative effect on MOR. In general, applying PF first during the blending process in manufacturing wood-strand composites leads to improved performance in terms of mechanical and physical properties. Results indicate a percentage-dependent effect of PVAc on the interference between PF and wood strands. Because PVAc has good deformability, it can evenly transfer stress from strand to strand, increasing bond strength. However, there is an inverse effect of PVAc under severe RH treatment because of the poor water resistance of PVAc. A PF/PVAc ratio range from 1:0.6 to 1:0.77 is suggested as an optimized ratio in hot-pressing of wood-strand composites.
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Details
- Title
- Characterization of PF/PVAC hybrid adhesive-wood interaction and its effect on wood strand composites performance
- Creators
- Yang Cao
- Contributors
- Vikram Yadama (Degree Supervisor)Jinwen Zhang (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Civil and Environmental Engineering, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525025901842
- Language
- English
- Resource Type
- Thesis