Лако-красочные материалы — производство

Today, wood constructions are becoming increasingly popular worldwide. However, they are no longer limited to rustic, single-family houses and bridges or austere factory buildings, but rather cover all modern designs. Certainly, ecological reasons (wood is a CO2 neutral, regrowing raw material) play an important role here. The fact that wood constructions may be prefabricated industrially […]

8.4.1.5 Development The groundbreaking technology oflaminated wood constructions, invented by the carpenter Otto Karl Friedrich Hetzer (1846-1911) from Weimar in Germany, is the supreme discipline of wood bonding. Until the 1950s, Hetzer’s name was synony­mous with beam constructions made from layers oflaminated wood boards, today called ‘glu(e)lam’. Several types of adhesive have been used for […]

Currently a wide array of wood-to-wood or wood to other materials composites is available, varying almost indefinitely in material and geometry. The only limits are set by the imagination of the engineers and designers, and any attempt of classification will be largely in the eye of the beholder. However, for the purpose of the present […]

In chemically setting systems, a polymerization takes place in the bond-line during compression, followed by crosslinking of the polymer molecules. This results in an increase in the average molecular weight of the basic polymers, inducing in turn a considerable increase in the strength values compared to the noncrosslinked matrix. Furthermore, the crosslinking results in transfer […]

8.4.1.3 Physically Setting Systems The ‘workhorse’ of the wood processing industry, apart from the manufacture of engineered wood products made from strands and fibers, is white glue, an adhesive based on polyvinyl acetate dispersions, either in the form of homopolymers or copolymers in combination with acrylates or functional monomers (e. g. malein acid derivatives). The […]

Historically, and up to the early 20th century, aqueous natural glues were used for bonding wood (see Section 5.9). For structural purposes, animal glues were preferred to plant glues as they generally produced higher strengths in the bond-line. Animal glues are composed of proteins that are responsible for both adherence (adhesion) and strength (cohesion). They […]

A wide array of adhesive raw materials and formulations is available for the purpose of different applications, such as required performance of the adhesive joint, and the chemical and physical properties of the wood-based materials (as described above). Summer wood — Spring wood — Summer wood — Summer wood Spring wood Spring wood Figure 8.19 […]

It is well known that the adhesion of an adhesive at the interfaces of the substrates depends on physico-chemical interactions and mechanical interlocking [23]. Apriori, in the case of porous surfaces, there is a larger area per joint section, and cavities enable the ‘tentacles’ of the adhesive to penetrate into the substrate. Machining techniques such […]

8.4.1.2 Strength, Swelling and Shrinking The radial symmetry of the stem and the arrangement of the cellulose fibrils in longitudinal direction have an important effect on the mechanical and adhesive properties. It has already been mentioned that the parallel and perpendicular tensile strengths differ considerably. The important swelling and shrinking behavior, which depends on the […]

For material and bonding technologies, an important factor here is the fact that, in a stem section, from the center of the stem to the outside layers, the features of the wood change. In many species of wood, at the center of the stem there is the ‘heart’ where the storage cells (pith rays) are […]