Efficiency of High-Frequency Pressing of Spruce Laminated Timber Bonded with Casein Adhesives

This study identifies the importance of reducing press times by employing high-frequency pressing of spruce-laminated timber bound with sustainable casein adhesives. Spruce lamellas with dimensions of 12 × 10 × 75 cm were bonded into five-layered laminated timber and then separated into single-layer...

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Bibliographic Details
Published in:Polymers 2021-12, Vol.13 (23), p.4237
Main Authors: Herzog, Andreas, Kerschbaumer, Tobias, Schwarzenbrunner, Ronald, Barbu, Marius-Cătălin, Petutschnigg, Alexander, Tudor, Eugenia Mariana
Format: Article
Language:English
Subjects:
Adhesives
Bond strength
Bonding strength
Casein
Chymosin
Cold
Compression tests
Compressive strength
Humidity
Mechanical properties
Modulus of elasticity
Modulus of rupture
Panels
Phenols
Polyvinyl acetates
Pressing
Room temperature
Shear strength
Timber
Viscosity
Workability
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Summary:This study identifies the importance of reducing press times by employing high-frequency pressing of spruce-laminated timber bound with sustainable casein adhesives. Spruce lamellas with dimensions of 12 × 10 × 75 cm were bonded into five-layered laminated timber and then separated into single-layer solid wood panels. Three types of casein (acid casein from two sources and rennin) were used. To compare the effectiveness of the casein formulation, two control samples bonded with polyvinyl acetate (PVAc) adhesive were pressed at room temperature (20 °C) and also with high-frequency equipment. The tests included compression shear strength, modulus of rupture, modulus of elasticity and screw withdrawal resistance on the wood panel surface and in the glue line. The average values of casein-bonded samples compression strengths ranged from 1.16 N/mm2 and 2.28 N/mm2, for modulus of rupture (MOR) were measured 85 N/mm2 to 101 N/mm2 and for modulus of elasticity (MOE) 12,200 N/mm2 to 14,300 N/mm2. The screw withdrawal resistance (SWR) on the surface of the wood panels ranged from 91 N/mm to 117 N/mm and in the adhesive line from 91 N/mm to 118 N/mm. Control samples bonded with PVAc adhesive did not perform better for compression shear strength, MOR and MOE, but for SWR in the adhesive line with 114 N/mm. Casein-bonded spruce timber pressed with HF equipment represents a sustainable new product with reduced press times, hazardous emissions and improved workability.
ISSN:2073-4360
2073-4360
DOI:10.3390/polym13234237