VOLUME 62, ISSUE 4/2021

The new additive manufacturing process Individual Layer Fabrication (ILF) is used to create components from individual layers (IL). The IL are produced by selectively binding wood chips with adhesive and using mechanical pressure. This enables the production of free-form geometries with high mechanical properties while requiring little binder. The localized adhesive application is carried out with a valve system onto scattered wood chips from above. Different material and process parameters such as thickness, density and adhesive content were considered. Bending and tensile tests perpendicular to the plane as well as thickness swelling after water immersion were carried out to characterize the produced IL. The process capability of ILF was proven and the determined characteristic values show promising results.

For the optimization of mechanical properties of structural profiles made of WPC is the method of prestressing with an asymmetrical compression researched. The results of different eccentricities and varying prestress forces were examined with a three-point bending test and a dynamic test with increasing force. During the static tests was an increase of the breaking force of up to 15 % with increasing eccentricity and pre-stress force observable. In the dynamic tests was not only an increase of the breaking force but also a higher cycle rate of up to 8.7 % noted.

The aim of a joint project (feasibility phase) was to investigate the manufacturability of bulk and blow-in insulation materials from maize spindles, as a by-product of grain maize cultivation. The tasks of the Institut für Holztechnologie Dresden (IHD) sub-project were the determination of important insulation properties and tests on processing. Furthermore, information on a possible approval procedure as building material was compiled. This article reports on the main investigations carried out at the IHD and their results. With the determined thermal conductivities of 0.030 W/mK to 0.045 W/mK, most of the test variants can be considered thermally insulating. The material exhibits a microbial load similar to other regrowing insulation materials (e. g. hemp). However, sufficient mould resistance is not given and would have to be ensured by suitable additional measures. With the determined fire behaviour of class E according to EN 13501-1 (2019), the maize spindle insulation materials meet the minimum requirements for building materials (combustible, normally inflammable). As expected, the tested variants could only be processed with great difficulty using a blow-in machine. Pneumatic installation, as is common with cellulose and wood fibre insulation materials, is hardly possible. The strong settlement of 5 % under severe climatic conditions and 14 % under impact stress also speaks against use in vertical or inclined compartments. How-ever, use as an openly poured or inflated insulation material, e. g. for storey ceilings, seems conceivable.

End-grain cross-sections of indigenous wood species were to be investigated for their suitability as fingerboard surfaces for guitars. This work deals with the investigations of the dyeing technology. Here, dye impregnation, thermal treatment and ammonia treatment were tested. In addition, selected combinations were carried out in the form of a double modification. The modified wood samples were examined with regard to the change in wood moisture content, swelling, surface hardness and colour change. UV irradiation was also carried out. The modifications differed greatly with regard to the change in properties. The double modifications by ammonia treatment and subsequent thermal treatment lead to dark brown tones, low swelling and high surface hardness. Whether the improved dimensional stability is sufficient for the use of end-grain fingerboards has to be determined by further investigations.

There are normative fire protection requirements for the use of materials in ships. A central requirement for separating walls is the fire resistance and non-combustibility of the used materials. There was no known wood-based material that is classified as non-combustible. Therefore, the aim of this work was to develop such a material. It was possible to develop a hybrid plywood which contains an 8 mm thick expanded glass as core material and which passes the non-combustibility test in thicknesses between 12 mm and 25 mm and achieves a fire resistance duration of 30 min. In addition to the fire properties, this material has similar mechanical properties to classic plywood and fulfils the requirements of the principles for the health assessment of building products with regard to emission behaviour.

Due to the increasing demand of environmentally friendly wood panels worldwide, wood

panels producers and scientists are looking for renewable adhesive systems (green adhesive)

as an alternative for synthetic adhesives from fossil sources. This interest in these bio-based

adhesives has arisen to minimize the health effects relating to product emissions of volatile

organic chemicals (VOCs), most notably formaldehyde. One possible source of bio-based material

for the development of green adhesives is from rapeseed press cake. The objective of this

study was to identify the effective rapeseed press cake protein fractions for use in formulating

an adhesive system for particleboard (PB). In order to determine the best protein fractions that

can be used as a basis for formulating adhesive recipes for PB. It was relied on estimating the

internal bond strength IB (EN 319, 1993) of the nine manufactured variants of PB bonded by

different rapeseed press cake protein fractions. The results reveal that, the protein fractions S3

(wet fractionated press cake) and S4 (protein concentrate) were considered as the best two

protein fractions to devise adhesive recipes for PB at lab scale. The PB variants bonded by

adhesive recipes based on protein fractions S3 and S4 have achieved IB values, which comply

with the specifications for PB type P1 and/or type P2 listed in EN 312 (2010). Moreover, they

have achieved formaldehyde release values comply with the standard value listed in EN 312

(2010) “Emission class E1” and can be considered as ultra-low formaldehyde emission PB.