Thesis
A mechanism to improve durability of oriented strand composite
Washington State University
Master of Science (MS), Washington State University
2006
Handle:
https://hdl.handle.net/2376/539
Abstract
Recent research indicates that the first losses in properties of wood-based composites are more to do with wetting as a result of moisture infiltration than fungal attack. Thus, improving moisture resistance of the OSC panels is a means of improving the durability, as susceptibility to moisture leads to rapid degradation of wood composites. A mechanism to improve durability of oriented strand composites (OSC) while attempting not to significantly compromise the mechanical properties is presented in this thesis. Objectives of the study were two fold: investigate the effects of blending maleic anhydride polyolefins (MAPO) with phenol formaldehyde resin on its toughness; and, understand the influence of varying levels of phenol formaldehyde (PF) resin and proportions of co-polymer coupling agent on physical and mechanical properties of oriented strand composite. Anionic emulsion of MAPO was found to be most effective in achieving a resin blend with uniform distribution of additive in PF resin. Cure kinetics of the adhesive blends were evaluated using differential scanning calorimetry (DSC). Effects of MAPO addition on stiffness and toughness were studied using DMA and mode I fracture cleavage analysis to assist in choosing either MAPE or MAPP for use in the second objective of the study, evaluating influence of higher levels of PF with and without MAPO on OSC properties. MAPP anionic emulsion improved toughness of resin better than MAPE, even after 24-hr water soak; thus, MAPP anionic emulsion was chosen to apply along with PF resin to in fabricating OSC test panels. Effects of different proportions of adhesive and MAPP on physical and mechanical properties of OSC were evaluated. Addition of MAPP did not significantly reduce MOE of test panels, however had significantly reduced MOR and IB especially at higher levels of MAPP. Use of higher levels of PF significantly improved the mechanical properties; however, addition of MAPP at high levels of PF was detrimental to board mechanical properties with improvements in moisture resistance. Moisture resistance of OSC test panels were investigated by measuring material permeance, diffusion constant and water absorption and thickness swelling. MAPP significantly improved moisture resistance properties of OSC panels. Based on the results of this study, it is believed that a better solution to improving moisture resistance without significantly reducing the mechanical properties is to increase the levels of PF resin in composite panels. MAPP, though improves moisture resistance, has a tendency to significantly reduce mechanical properties, especially MOR and IB.
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Details
- Title
- A mechanism to improve durability of oriented strand composite
- Creators
- Sudip Chowdhury
- Contributors
- Vikram Yadama (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Voiland College of Engineering and Architecture
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900525276601842
- Language
- English
- Resource Type
- Thesis