tailieunhanh - Báo cáo lâm nghiệp: "Determination of the pressing parameters of spruce water-resistant plywood"

Tuyển tập những bài báo cáo nghiên cứu khoa học hay nhất được đăng trên tạp chí JOURNAL OF FOREST SCIENCE đề tài: Determination of the pressing parameters of spruce water-resistant plywood. | JOURNAL OF FOREST SCIENCE 53 2007 5 231-242 Determination of the pressing parameters of spruce water-resistant plywood J. Hrazsky P. Král Faculty of Forestry and Wood Technology Mendel University of Agriculture and Forestry Brno Brno Czech Republic ABSTRACT The paper summarizes results of operations aimed at determining the pressing parameters of spruce water-resistant plywood and testing the suitability of particular constructions of plywood. Constant and variable parameters were determined. In pressed plywood sheets the shearing strength of gluing according to EW 100 and the coefficient of compressibility were determined. In pressing heat transmission through the set of veneers was analyzed and effects of the moisture of veneers on heat transmission were tested. The percentage of resin hardening was also determined. Results were statistically analyzed. The dependence was determined of shearing strength coefficient of compressibility and heat transmission on changes in pressing parameters. Results of the study consist in the proposal of pressing parameters for particular constructions of plywood. Keywords plywood gluing strength veneer plywood construction statistical evaluation Since the beginning of human civilization man has used a renewable resource wood raw material which is probably one of the most important products of the vegetable kingdom. Wood from felled trees caused some problems to users and processors the most serious of the problems was the conversion of stems to forms suitable for construction or other purposes. These problems induced the need of new processing technologies for the manufacture of wood-based materials . veneers plywood solid glued products agglomerated materials and other wood composites. Wood becomes a shortage material all over the world it must be imported for processing into industrial agglomerations and its price on world markets increases. Diminishing raw material resources and the shortage of natural wood lead to the .