Environmentally-Friendly High-Density Polyethylene-Bonded Plywood Panels

Abstract

Thermoplastic films exhibit good potential to be used as adhesives for the production of veneer-based composites. This work presents the first effort to develop and evaluate composites based on alder veneers and high-density polyethylene (HDPE) film. The effects of hot-pressing temperature (140, 160, and 180 °C), hot-pressing pressure (0.8, 1.2, and 1.6 MPa), hot-pressing time (1, 2, 3, and 5 min), and type of adhesives on the physical and mechanical properties of alder plywood panels were investigated. The effects of these variables on the core-layer temperature during the hot pressing of multiplywood panels using various adhesives were also studied. Three types of adhesives were used: urea–formaldehyde (UF), phenol–formaldehyde (PF), and HDPE film. UF and PF adhesives were used for the comparison. The findings of this work indicate that formaldehyde-free HDPE film adhesive gave values of mechanical properties of alder plywood panels that are comparable to those obtained with traditional UF and PF adhesives, even though the adhesive dosage and pressing pressure were lower than when UF and PF adhesives were used. The obtained bonding strength values of HDPE-bonded alder plywood panels ranged from 0.74 to 2.38 MPa and met the European Standard EN 314-2 for Class 1 plywood. The optimum conditions for the bonding of HDPE plywood were 160 °C, 0.8 MPa, and 3 min.

Poly-(3-ethyl-3-hydroxymethyl)oxetanes—Synthesis and Adhesive Interactions with Polar Substrates

“…It is noteworthy that the observed shear strength of the 1:20 series exceeded the minimum required for plywood (≥1.0 MPa) [50] and were comparable to those reported for poly(lactide)-poly(ε-caprolactone)-based and ethylene-vinyl acetate based hot-melt adhesives (0.6-1.5 MPa [51]) but still lower than those reported for FeCl 3 -curable polyoxetanes [30]. Bekhta and Sedliačik investigated plywood bonding with HDPE and demonstrated that shear strengths of the bond-lines greatly depended on the time, pressure, and temperature of the process [52]. The authors obtained the highest strengths for a 160 • C temperature and a 3 min press time, which were necessary for proper penetration of the molten adhesive into the substrate.…”

Geopolymer-Bonded Laminated Veneer Lumber as Environmentally Friendly and Formaldehyde-Free Product: Effect of Various Additives on Geopolymer Binder Features

“…The level of wood failure is somewhat dependent on the level and type of bonding mechanisms created between the wood cells and the binder. Wood is a porous material; hence, a mechanical interlock is the most likely bonding mechanism involved between the wood cells and the inorganic binder [9,11,27]. Chemical bonding formation between the wood and any mineral components, especially geopolymer binder, has not yet been proven [11].…”

“…Adequate adhesion between two materials (similar or dissimilar) is of great importance for determining the final application of resultant products. The requisite adhesion strength between the materials stems from the intrinsic adhesion forces across the interface of materials, as well as the toughness of adhesive joints [6,27]. Although extensive research has been conducted on bonding improvements of wood with synthetic binders, there are only few studies on wood and inorganic binders [20,28].…”

Advances in Wood Composites

“…Bekhta and Sedliacik [28], presented the first effort to develop and evaluate composites based on alder veneers and high-density polyethylene (HDPE) film, since it was known that thermoplastic films exhibit good potential to be used as adhesives for the production of veneer-based composites. Three types of adhesives were used: urea-formaldehyde (UF), phenol-formaldehyde (PF), and HDPE film.…”