Combing And Drying Technology Of Biomass Materials On Reconstituted Square Lumber

In order to improve the utilization of straws and small-diameter logs, reconstituted square lumber come into being. This study analyzed the relationship between the fiber bundle shape and mechanical properties of the reconstituted square lumber, while using scanning electron microscope, fluorescence microscope and FTIR observed the micro structure of different type reconstituted square lumber. Softening processing of cotton stalks and mulberry branch were studied while the minimum moisture content of fiber bundle was selected by compaction experiment. Combined mechanical property of rolling and combing fiber bundle test and the relationship between the fiber bundle shape and mechanical properties of the reconstituted square lumber, the single factor experiment and orthogonal experiment on drying the rolling and combing fiber bundle was arranged in order to determine the reasonable technology on fiber bundle drying.The main results were as follows:(1) Manufacturing PF reconstituted square lumber with the size 400 mm×50 mm×40 mm, the structure were more densification with thinner rolling and combing fiber bundle whether made from cotton stalk and mulberry branch. In addition, the structure on reconstituted square lumber made from cotton stalk was better than reconstituted square lumber made from mulberry branch. In the same setting conditions(density of 0.70 g/cm3), mechanical properties of reconstituted square lumber made from mulberry branch were higher than reconstituted square lumber made from cotton stalk, while the shape of rolling and combing fiber bundle had significant effect on mechanical properties of reconstituted square lumber. Sample M2 and S2 of reconstituted square lumber had a good bending strength and modulus of elasticity, while sample M1 and S1 had a good compressive strength parallel to grain. Therefore, the reasonable preparation process should be controlled after determining the application of reconstituted square lumber.(2) Sample M1 and S1 of reconstituted square lumber had relatively complete cell morphology, and clearly arranged in comparison rules, while sample M2, M3 and S2, S3 had certain the degree of compression and deformation in tangential and radial direction during the hot-pressing process by SEM. The thresholding images of reconstituted square lumber show that the adhesive thickness can be reduced as the ratio of width to thickness decreases. The adhesive thickness in reconstituted square lumber made from cotton stalk was far less than the reconstituted square lumber made from mulberry branch with the same conditions fiber bundle shape. The results of FTIR showed that effective chemical reaction possibly occurred between adhesives group of PF and chemical components of the fiber bundle during hot-pressing.(3) The optimum rolling and combing technology under the laboratory conditions was that the moisture content of cotton stalk more than 50.80 % and mulberry branch more than 81.46 % can obtain the better fiber bundle shape.(4) Orthogonal experiments of rolling and combing fiber bundle showed that within test conditions, each factor impact on the drying time of cotton stalk fiber bundle in turn were the initial moisture content, air temperature, the loading rate. Each factor impact on the drying time of mulberry branch fiber bundle in turn were air temperature, the initial moisture content and the loading rate. The optimum drying technology under the current conditions for cotton stalk fiber bundle was that the initial moisture content was 60 %, the air temperature was 110 ℃and the loading rate was 35 %, while the optimum drying technology for mulberry branch fiber bundle was that the air temperature was 120 ℃, the initial moisture content was 80 % and the loading rate was 45 %.