Hans-Jörg Gusovius

Wet Processing of Hemp: An Overview

Normally, the production of fibers from agricultural fiber crops is based on field drying and retting of plant straw. As weather conditions at the usual harvest time are often problematical for harvesting and retting, the development of weather-independent supply chain technologies is very important. The weather risk can be avoided, if, e.g., hemp after being harvested with a conventional forage harvester is directly processed to final products, or stored by wet preservation. Furthermore advantageous is that the whole plant material without any loss is processed to final products like fiber boards, insulation materials, or fibrous materials for natural fiber reinforced composites. Especially for this purpose a pilot plant has been built up and is tested till present. The investigations have shown that conventional technologies of ensiling are capable for the preservation of hemp for more than one year.

Processing of Wet Preserved Natural Fibers with Injection Molding Compounding (IMC)

The paper shows selected results of a comprehensive national network activity related to the integrated value chain for new whole plant based fibrous raw materials. Therefore, both the supply of raw materials and the processing with the innovative one step technology injection molding compounding (IMC)—are optimized. As a result the fiber length in the product is longer compared to the standard two-step process with pelletizing. The new technology helps in improving the manufacturing of fiber reinforced composites by considering the integrated value chain.

Wet-preserved hemp fibreboard properties improvement with veneering

The initial research describes a new type of fiber boards for the furniture interior design, developed in cooperation with ATB (Leibniz-Institute for Agricultural Engineering) by using a new method of raw materials preparation and specific production technologies of ATB. The main raw materials are aerobically aged hemp stalks. The samples are made of hemp chips with a long preservation time and fastened together with the UF glue. Specimens are 8 mm thick and correspond to a medium-density fiberboard, fitting standard EN622. Due to the fact that non-veneered material can be used only in non-load-bearing constructions, material improving technologies were studied, such as increase of board density, increase of glue percentage, partially substitution of wet-preserved hemp chips with a dry hemp and/or wooden chips to equalize moisture content of obtained mixture. The particular article describes how the new material is veneered with the oak veneer obtaining three-ply composite board with the improved mechanic...

Design of Competitive Processing Plants for Hemp Fibre Production

Despite an annually growing demand for natural fibres accompanied by worldwide increasing fibre prices as well as long tradition and experience in fibre processing, the production facilities for hemp and flax fibres are very limited in Europe. At present, the lack of modern harvesting and economic processing technologies seem to be the greatest obstacles for hemp fibre producers under the changing conditions of international raw material markets. Therefore, detailed investigations of all process stages of hemp fibre processing have been carried out at the Leibniz Institute for Agricultural Engineering (ATB). A novel hemp processing line has been developed, installed, and tested at industrial scale in the last 3 years. Investigations regarding optimum plant layout have shown that a straw throughput of approximately 4 t h−1 is required for economic fibre production for all new processing lines at currently high straw prices of more than 150 € t−1. Throughputs in the range from 4 to 6 t h−1 showed a favourable relation between profit and investment cost. At throughputs higher than 6 t h−1, the profit per ton processed straw can be further increased. But investment and straw logistic cost increase at these high-throughput levels often much faster.

Moisture absorption properties of hardwood veneers modified by a sol-gel process

Abstract A new invisible nanolevel coating has been developed based on the sol-gel process for veneer finishes. The sol synthesis and its application as a protective agent is described. It could be demonstrated that a combination of organic light stabilizers and sol-gel deposits is feasible and that the resulting hybrid inorganic-organic thin films decrease moisture uptake of hardwood veneers.