Highly Densified Laminated Composites with Pre-Compressed Veneers, ProLigno

The objective of this study is to evaluate the physical and mechanical properties of highly compressed
beech veneers (compression rate up to 40%) used for the manufacture of laminated products with high
density. Dimensional stability, elastic properties, Brinell hardness and the quality of bonding were tested.
Conventional (PVAc, MUF and PUR) and alternative adhesives (based on casein) were used for the bonding
of 7-layered laminated veneer-based high-density products. Based on the results of the study, a
compression rate of 40 % was reached for all composites. Tensile shear strength of all panels was from 1.3
up to 3.3-fold higher than that of control (pagholz, as an industrial product) and modulus of elasticity
exhibited higher values in the case of using polyurethane and melamine urea-formaldehyde. Thickness
swelling and water absorption after 24 hours, bending strength and Brinell hardness should be improved by
changing pressing and processing parameters. The spring-back effect was the lowest (7%) and the highest
(14%) for the compressed veneers with MUF, respective casein adhesive application. Casein-based
adhesive application for laminated veneer products (LVP) is an alternative for a completely recyclable and
sustainable product. These LVP can be applied in buildings as wear layers between beams or in contact with
other materials (concrete). Their use reduces the cross-section of the element, increases safety during use
and significantly reduces the consumption of raw materials, extends the products service life and ensures a
higher resistance to climatic factors compared to solid wood (i.e. GLT, CLT, SWP)