Physical and Mechanical Properties of High-Density Fiberboard Bonded with Bio-Based Adhesives

Abstract

The high demand for wood-based composites generates a greater use of wood adhesives. The current industrial challenge is to develop modified synthetic adhesives to remove harmful formaldehyde, and to test natural adhesives. The scope of the current research included the manufacturing of high-density fiberboards (HDF) using natural binders such as polylactic acid (PLA), polycaprolactone (PCL), and thermoplastic starch (TPS) with different resination (12%, 15%, 20%). The HDF with biopolymers was compared to a reference HDF, manufactured following the example of industrial technology, with commonly used adhesives such as urea-formaldehyde (UF) resin. Different mechanical and physical properties were determined, namely modulus of rupture (MOR), modulus of elasticity (MOE), internal bonding strength (IB), thickness swelling (TS), water absorption (WA), surface water absorption (SWA), contact angle, as well as density profile; scanning electron microscope (SEM) analysis was also performed. The results showed that increasing the binder content significantly improved the mechanical properties of the panels in the case of starch binder (MOR from 31.35 N mm−2 to 40.10 N mm−2, IB from 0.24 N mm−2 to 0.39 N mm−2 for dry starch), and reduces these in the case of PLA and PCL. The wet method of starch addition improved the mechanical properties of panels; however, it negatively influenced the reaction of the panels to water (WA 90.3% for dry starch and 105.9% for wet starch after 24 h soaking). Due to dynamically evaporating solvents from the PLA and PCL binding mixtures, a development of the fibers’ resination (blending) techniques should be performed, to avoid the uneven spreading of the binder over the resinated material.

The Influence of the Content of Recycled Natural Leather Residue Particles on the Properties of High-Density Fiberboards

“…The in-time decreasing contact angle, as well as the surface roughness-contact angle relation can be confirmed by [27]. As it has been proven by Gumowska and Kowaluk [28], the contact angle can influence the physical properties of fiberboards.…”

Improvements in the Production of Isosorbide Monomethacrylate Using a Biobased Catalyst and Liquid–Liquid Extraction Isolation for Modifications of Oil-Based Resins

“…Various thermoset precursors can be mentioned providing named characteristics such as modified (epoxidized, acrylated, or methacrylated) vegetable oils; − curable derivates of standard polyols (ethylene glycol, glycerol, erythritol, sorbitol) − or other biobased structures able to be modified to reactive products (vanillin, ascorbic acid, alkyl carboxylates). − All appointed representatives fulfill the natural origin, but particular applications of curable precursors require specific physical–chemical properties such as appropriate rheological behavior, sufficient material strength/flexibility, or predictable surface tension and surface energy of formed cured resins. Suitable viscosity levels are essential for all coating systems due to the varying nature of treated substrates and the very thin layering requirements that can be formed most efficiently from precursors possessing low-viscosity values. , Mechanical protective applications depend upon appropriate elastic modulus values and glass transition temperatures of formed thermosets since their rigidity/flexibility is the key exhibited property. , The adhesion and permeability are primarily dependent on the surface tension and energy of curable precursors and formed resins since the overall interaction with the surroundings, such as swelling or diffusion, is influenced by the number of molecular interactions of either nonpolar or polar attraction forces. − …”

The analysis of response surface optimization and performance of cross‐linked starch/tannic acid adhesive reinforced by phragmites fibers

“…Therefore, developing new adhesives from modified starch and its derivatives is the only way to generalize and apply SBAs in industry. At present, starch is mainly modified by physical, chemical, or biological enzyme methods to expand the application of these adhesives 13,14 . For example, oxidation can break the glycosidic bond on the molecular chain and shift large starch molecules into little ones, thus reducing the viscosity of SBAs 15 .…”

“…At present, starch is mainly modified by physical, chemical, or biological enzyme methods to expand the application of these adhesives. 13,14 For example, oxidation can break the glycosidic bond on the molecular chain and shift large starch molecules into little ones, thus reducing the viscosity of SBAs. 15 Meanwhile, the carboxyl and carbonyl groups have better binding force to wood products, and when the adhesive layer is cured, it shows more excellent mechanical properties.…”