Study On The Preparation And Performance Of Outdoor And Weathering Resistance Reconsolidated Bamboo

With the increasing shortage of wood resources in China, rich and renewable bamboo resources with a short production cycle is becoming an important source of wooden materials. Due to the limitation of its shape, traditional bamboo resources are always tubular and lathlike, which are difficult to be made into plate shape, and greatly affected their practical application. The limitation always leads to the low utilization of bamboo and restricted the development of bamboo resources industry. To utilize the bamboo resources in a more scientific and reasonable way, improve their utilization, bring their physical and mechanical properties into full play, reduce the energy consumption in the process of reconsolidated bamboo preparation and the emission of carbon dioxide, the essay mainly focuses on the study of scuffing molding technology of reconsolidated bamboo with mao bamboo as the raw materials, including the following parts:the study chooses mao bamboo as the raw materials, and discusses the physical and mechanical properties and aging resistance of reconsolidated bamboo, and the production of reconsolidated bamboo with the self-made moderate temperature curing phenolic resin as the adhesive. The essay studies the preparation technology of moderate temperature curing phenolic resin, optimizes the preparation technology of adhesive through orthogonal experiment, and characterizes the structure of phenolic resin through Fourier infrared spectrum and differential scanning calorimeter (DSC). The study conducts the single factor experiment on the crushing times, content of solid in glue solution, density, hot pressing temperature and time, and makes optimization analysis on the technology of reconsolidated bamboo in hot pressure through response surface experiment. It also makes the preliminary comment of the weathering resistance on the produced reconsolidated bamboo. The main conclusions are as follows:(1) NaOH has a better catalytic effect than Ba(OH)2 when both NaOH and Ba(OH)2 are used as catalysts. The adding amount of NaOH has the most significant effect on the viscosity, water soluble times and curing time of phenolic resin adhesive, and that of Ba(OH)2 also has a significant effect on the performance of phenolic resin adhesive. However, the adding time of Ba(OH)2 has no significant effect on the performance of phenolic resin adhesive. The best technology conditions through orthogonal experiment are as follows:the adding amount of NaOH is 0.2mol, the adding time of Ba(OH)2 is 60 ℃, and the adding amount of Ba(OH)2 is 0.05mol.(2) The adding amount of resorcinol has a greater effect on the performance of phenolic resin glue solution. With the gradual increase of the adding amount of resorcinol, the time of the darkening of glue solution’s color and the curing have been gradually shortened, viscosity enhanced and water solubility improved. When resorcinol is added at an early time, the color is relatively dark, and curing time is short with a good water solubility and big viscosity. With the delay of the addition of resorcinol, the water solubility and viscosity of glue solution is getting smaller with a light color and extended curing time. Through the analysis of Fourier infrared spectrum and DSC, the highly active neighbor-neighbor structure in adhesive has been gradually reduced with the delay of the addition of Ba(OH)2. The addition of resorcinol has effectively improved the content of para structure in glue solution. The results of DSC show that the curing temperature and heat output gradually lower with the addition of Ba(OH)2 and resorcinol, which also indicates that the curing rate improves.(3)Through the analysis of single factor experiment, it is confirmed that three times are the best crushing times for bamboo-bundle assembly, and the bamboo-bundle assembly after been crushed for three times enjoy the best physical and mechanical properties. Phenolic resin with 25% solid content has the best effect for gum dipping of bamboo-bundle, and the amount of the impregnation glue is 30%. Through previous analysis of the single factor experiment, the response surface value range of density, the hot pressing temperature and the time during the technology in manufacturing reconsolidated bamboo is confirmed. By systematic optimization of hot-pressing technology of reconsolidated bamboo based on the optimized response surface, the result shows that density has the most significant effect on the physical and mechanical properties of reconsolidated bamboo, temperature in hot pressure some and the time in hot pressure the least. The parameter for hot-pressing technology is determined as follows:density is 103g/cm3, temperature in hot pressure is 125℃ and time in hot pressure is 1.2min/mm. Then, reconsolidated bamboo is prepared based on the optimized technology parameter, further experiment is conducted to verify the parameter, and the result of each experiment shows that reconsolidated bamboo is in line with the national standard.(4)Through the contrast test analysis of mechanical properties of three types of reconsolidated bamboos, the following conclusions can be drawn:physical and mechanical properties of reconsolidated bamboo pressed by moderate temperature curing phenolic resin are better than other two bamboo products, with the improvement of MOR, MOE and IB. Repeated water boiling resistance and drying resistance of reconsolidated bamboo pressed by moderate temperature curing phenolic resin are better than other two reconsolidated bamboo products. The thickness swelling content of reconsolidated bamboo is only 1/5-1/4 of other two materials. Through Xenon Lamp Aging Treatment Experiment, it proves that reconsolidated bamboo has certain performance of outdoor aging resistance. After 600-hour aging treatment, MOR, MOE, and IB decrease 13.04%、9.78% and 10.08% respectively, better than other two products.