Liquefaction Of Wood In Phenol And The Resinification Of The Phenolated Wood

As a kind of renewable and biodegradable natural material, wood is one of the most prospect materials in the 21st century. In order to effectively utilize the woody resources and to protect environment, it is very important to explore application fields of wood. Liquefaction of wood is a new technique, which is a novel process to effectively convert chemical components of wood (including cellulose, hemicellulose and lignin ) into a polymer with high additional values that can be used in producing adhesives, polyurethane, moldings or carbon fibers.Based on the analysis of the effect of four kinds of inorganic acid on wood liquefaction, phosphoric acid is selected as catalyst of wood (Poplar and Chinese fir) liquefaction in phenol in this study. The factors influencing wood liquefaction are analyzed and the optimum liquefaction processing parameters are defined. The main chemical components, such as holocellulose, cellulose and lignin, are measured and extracted according to GB methods, and they are liquefied in the same condition. The liquefied products of these main chemical components are analyzed by using gel permeation chromatography (GPC), Fourier transform infrared (FTIR), high performance liquid chromatograph (HPLC) and nuclear magnetic resonance (NMR) to clarify the mechanism of wood liquefaction in phenol using phosphoric acid as catalyst. The liquefied resultant from the raw materials of Poplar and Chinese fir are used to synthesize with formaldehyde to make resin, respectively. The factors influencing during the resinification and the properties of new resin are studied; the optimum processing parameters in resinification are confirmed with orthogonal test method. The new liquefied wood-based resin adhesives are used in plywood and molding materials. The glue strength and the moisture content of plywood are measured according to GB methods. And the compressive strength, the water-resistant ability and the biodegradability of the molding materials are determined. The following results are obtained.(1) The phosphoric acid (c=85%) and sulfuric acid (c=36%) are satisfactory as catalysts of wood liquefaction in phenol. Hydrochloric acid (c=37%) is easy to volatilize at higher temperature, and oxalic acid (c=99%) is the lowest as catalysts of the wood liquefaction in four kind of acids. Hydrochloric acid and oxalic acid are difficult to complete the liquefaction process, even at 180℃. Because the difference of the residue rates is small at temperatures ranging from 150℃ to 180℃, generally the temperature 150℃~160℃ is suitable for wood liquefaction when the energy consumption is the lowest.(2) The better result of wood liquefaction in phenol can be obtained when the amount of sulfuric acid (c=36%) as catalyst is more than 6% and the temperature is higher than 150℃. If the phosphoric acid (c=85%) is used as catalyst during the wood liquefaction in phenol, the good liquefaction effect can be obtained at the content of 10% and the temperature 150℃.(3) During the wood liquefaction, the residue rates of Chinese fir and Poplar markedly decreases with the increase of liquefaction temperature, time, catalyst content and ratio of phenol to wood. The result indicates that these factors play important roles on liquefaction of wood in phenol. Among them, the liquefaction of Poplar is more sensitive to temperature, and the residue rate of Chinese fir is affected by reaction time.(4) Using orthogonal test method, the results show that usually Chinese fir is liquefied more easily than Poplar in the same liquefaction condition, and its residue rate is lower. But the re-condensation will take place in liquefied Chinese fir when the temperature is at 180℃ and liquid ratio (phenol to wood ratio) is 4.5. The optimum condition of liquefaction for Poplar is: 180℃, 2.5h, liquid ratio 4.5 and catalyst content 8 %. At this condition, the residue rate of 5.0% could be get. Given the conditions of 180℃, the reaction time 2.5 h, the liquid ratio (phenol to wood ratio) 4 and the catalyst content 10 %, the residue rate of Chinese fi...