Processing of long woodchips is predominantly determined by the production of three-layered oriented strand boards (OSB) in double belt presses. In the conventional OSB manufacturing process, chips are wetted in a large-volume drum by a mixture of binder and additives, placed quasi-isotropic on the belt and compacted under temperature . Edges of a demolded two-dimensional product have to be shaped being cost intensive. Resulting mechanical properties of OSB plates are moderate since only a portion of the chips are aligned to a defined major load path. Utilized binder systems for OSB are based on diphenylmethane diisocyanate in the core layer and melamine-urea-formaldehyde in outer layers . In June 2014, formaldehyde was classified as carcino- and mutagenic by the EU .
This publication deals with a high performance wood plastic composite (HPWPC), that compensates all disadvantages of OSB, so that three-dimensional, rework-free, application-oriented and low-formaldehyde wood plastic components can be produced. In an experimental mold long woodchips were combined with diverse formaldehyde-free thermoplastic and thermoset matrices. Specific process parameters had to be elaborated considering viscosity as well as adhesion of the matrices and compaction rate of the chips. The measured density-specific bending strength (?/(?*g)) in fiber direction of a HPWPC specimen compacted at 100 bar and consisting of 10 % (w/w) PP as well as 90 % (w/w) long woodchip outperformed a reference OSB3 sample by 350 % and a comparable aluminum sample by 70 %. The proven lightweight potential coupled with the inexpensiveness of woodchips enables the use of HPWPC for applications in furniture, vehicles and construction.
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