Surface Tension and Wettability of CCA-Treated Red Maple

The wetting properties of untreated, water-extracted and chromated copper arsenate (CCA)-treated red maple were characterized by contact angle measurements. Conventional experimental and mathematical modeling were employed to evaluate the wetting parameters. Zisman's critical surface tensions, and both acid-base (γABs) and acid (γ+s) components of surface tension for CCA-treated wood do not differ much from those of untreated wood. After CCA-treatment, the dispersion (γds) and Lifshitz-van der Waal (γLWs) components of the surface tension increase while the polar (γps) and base (γ-s) components decrease. The high contact angles resulting from the water and CCA treatment of wood compared to untreated wood suggest poor wettability. CCA-treated wood wetted with phenol-formaldehyde (PF) adhesive gave contact angles greater than 90°, i.e., very poor wettability and the time to reach an equilibrium contact angle was three times longer than that for untreated wood

Influence of coupling agent in compatibility of post-consumer HDPE in thermoplastic composites reinforced with eucalyptus fiber

This study investigates the feasibility of using recycled high density polyethylene (HDPE) and wood fiber from species Eucalyptus grandis (EU) to manufacture experimental composite panels. The use of maleated polyethylene as coupling agent (CA) improved the compatibility between the fiber and plastic matrix. The mechanical properties of the resultant composites were compared with polymer with and without compatibilizer. The influence of the coupling agent (CA) in the polymer matrices and composites were evaluated at different concentrations, checking the physical, mechanical and thermal properties of wood plastic composites (WPC). Results of mechanical, physical and thermal properties showed that concentration of 3% w/w CA in the polymer matrices was that which showed the best results, but in the composites properties were very similar in all formulations. Based on the findings in this work, it appears that recycled materials can be used to manufacture value-added panels without having any significant adverse influence on material properties

Resinification of Alkali-Catalyzed Liquefied Phenolated Wood and its Characterization as the Novolak-Type Phenolic Resins

The reaction of wood meal with phenol resulted large amounts of non-reacted phenol, which further allowed reaction with formaldehyde. The effects of various reaction parameters for the preparation of wood-based phenolic resins on their properties have been discussed. The optimum conditions (i.e., 80% consumption of phenol) of wood-based phenolic resin preparation were found to be a formaldehyde:phenol mole ratio of 1.6:1, a pH of 2.51, a temperature of 130°C, and time 1 h. Both melt-flow behavior and molecular weight of the wood-based phenolic resins changed with the change in reaction parameters. For most cases, the melt-flow properties of the wood-based phenolic resins were close to those of commercial novolak resins. The flexural mechanical properties of wood flour-filled molded materials of wood-based phenolic resins, which were prepared at the formaldehyde:phenol mole ratios of 0.85:1 and 1.16:1, were comparable to those of commercial novolak resins. Moreover, molded wood-based phenolic resins, prepared at same mole ratios of formaldehyde:phenol, showed better resistance to immersion in water and burial in active composting soil in comparison with those prepared under other conditions. Generally, wood-based phenolic resins with higher reacted phenol had properties close to those of commercial novolak types. </jats:p