Influence Of Dyeing Treatments On The Performance Of Bamboo Scrimber

As a bamboo-based panel made from bamboo fibrosis veneer, bamboo-based fiber composite is an economic wood-substitution and can utilize the small-diameter bamboo efficiently. Because of its controllable density and other excellent physical/mechanical properties， bamboo-based fiber composite products have been widely used as indoor flooring furniture and decoration materials. However, with the breakthrough of bamboo-based fiber composite manufacturing technology, the demand for outdoor reconstituted bamboo lumber wasalso increasing and thus the lumber’s durability has become a research focus. Systematic research on the dyeing properties, weather resistance properties of bamboo-based fiber composite will be important for satisfying the demand for product diversification and providing the reference for research and production of bamboo-based fiber composites, and promoting its outdoor application and increase its added value.In this paper, Phyflostachys pubescens bamboo fibrosis veneer were chosen as basic raw materials. They are dye-treated with different method, and then reconstituted with phenol-formaldehyde adhesive and hot pressing process. The effect of dye-treatment on the physical, mechanical properties and surface color of bamboo-based fiber composite were studied. The properties of dye-treated bamboo-based fiber composite after outdoor aging test were analysed, the relationship between of outdoor aging test time and surface color, dimensional stability, weight loss rate were also discussed. The main results were summarized asfollows:（1） The surface color turned from light to dark as the dye-treated temperature and time increase. After applying the dye-treated method, the MOR and shear strength (parallelloading) are slightly reduced compared with the untreated specimens. The thickness swelling rate and water absorption rate of bamboo-based fiber composites were also increased by the dye treatment. According to the study, we also found that the bamboo fibrosis venee r dyed in alcohol at75°C and those dyed in water at90°C had a higher exhaustion rate than those dyed in water at20°C.（2）After3months’ outdoor aging test, the change of color, ΔL*、Δa*、Δb*valuewas declined gradually with the increase of the outdoor aging test time. The changes in dimensional stability and weight loss rate have shown similar trends with the time under different climate conditions.（3） According to the study, the physical, mechanical, and color properties of bamboo-based fiber composites (Phyflostachys pubescens) are all influenced by the presence of dyeing treatment. Remarkable colour changes were observed after dye treatment when the bamboo was dyed in alcohol source at75°C, while the MOR, MOE and shear strength (parallel loading) didn’t change much after the dye treatment. Therefore, we think that it is the optimum selection when the bamboo was dyed in alcohol source at75°C.（4） According to the study, a remarkable increase in color was observed in the bamboo’s transverse section and radial sections. We can observe that the vascular bundleof bamboo in the transverse section was nearly completely red. From the radial section,We can also observed that the color of fibers was nearly completely redder than the color of bamboo parenchymatous cells. In addition, the color of treated in alcohol was slight redder than the color of bamboo treated in water. This result shows that the method of dyeing in alcohol was helpful for improving the color strength.（5）The images of dyed raw bamboo culm and untreated raw bamboo culm withbasic grown G and acid black2by SEM are depicted in chapter6. The untreated rawbamboo culm sample had a comparably smooth surface, and the image of the dyed raw bamboo culm sample indicate that dye accumulate on the surface of fiber cell as afine spherical particle. The result indicate that dye particle size not larger than1μm. We can also observe the pit diameters in cells of approximately3to10μm, These results can be regarded as indicating that there was a favorable factors for the water-solublebasic dye molecules removed into the cell wall bamboo from pit.