Oriented strand board (OSB) from hot water extracted wood
Publication Name: Proceedings of ECOWOOD 08, 3rd International Conference on Environmentally-Compatible Forest Products
The increased cost of petroleum and policy changes due to concerns about climate change are game changing events which will create major changes in the economy. One concept that has received attention is that of a forest bio-refinery, wherein multiple products are produced. While integrated forest products complexes have been the norm for many years, the difference in biorefinery is the emphasis on chemical and materials production which compete with items traditionally manufactured from petroleum. There are several sulfite pulp mills in the world which produce a variety of chemicals in conjunction with the manufacture of pulp. In the United States, Red Shield Environmental is evaluating the potential for co-production of acetic acid and ethanol from a kraft mill facility. This concept, wherein multiple material and chemical products are produced from wood, can be
applied to other forest products production scenarios. The Oriented Strand Board composite industry is a good candidate due to large plant sizes as well as technical considerations including rapid mass transfer rates due to the thinness of the wood. The production of OSB in North America for 2006 was 14.24 million tones. A hot water extraction process primarily removes hemicellulose compounds. Assuming a 15% weight removal with subsequent conversions could result in an annual production of 5.19 million barrels of ethanol. Assuming a market for such an extract, the question becomes what is the influence of the extraction
on the behavior of the core high-value forest product? This research was conducted using three Red Maple (Acer Rubrum L.) trees, three strand thickness (0.025Ó, 0.035Ó, and 0.045Ó), and two hot water extraction time of 45 and 90 min. at 160 C and control (unextracted). One OSB panel was manufactured for
each of the 27 material combinations. Weight loss was significantly influenced by extraction time and tree source. The thickness swell and sorption isotherms of panels from extracted material was lower while its water absorption was significantly higher than the control. Fungal deterioration was similar for control and extracted material. The higher heating value was increased after hot water extraction. Modulus of rupture (MOR) was not statistically significant different between the unextracted and 45 minute extraction conditions but it was decreased after 90 minutes. Internal bond for both extraction time (wet and dry conditions) was significantly lower than the control. The distribution and size of pores within the cell wall increased as the extraction time increased. Contact angle indicated more pronounced liquid wetting and penetration for the extracted material. Inverse
gas chromatographic identified that dispersive surface free energy and acid characteristics increases with extraction time. The percentage of crystallinity of cellulose increased as a function of the extraction time.