| China is a country which is lack of forest resource, as the rapid development of national economic and the enhancement of environment-friendly consciousness, the demand of wood material more than before; the deficiency of wood is a bottleneck of Chinese complete economic development. The comprehensive of Chinese wood industry is much lower relatively, many wood factories produces lots of wood residues (wood chip, saw dust and remnant) which haven't been comprehensive utilized effectively; as the acceleration of urbanization and old city rebuilding, many wood waste materials have been produced in the process of construction relocation, the same as city construction and citizen apartment decoration; industrial products, physical distribution and dock warehousing, meeting and exhibition, department and supermarket and traffic etc. these waste wood material have been abandoned or burned basically, not only to generate environmental pollution but also to waste many biomass materials. More focuses have been put on the problem of using waste wood material. As the depletion of petroleum, coal and gas and so on, how to produce resin product by renewable source instead of oil has become one hot issue in the world. The article has chosen phenol as liquoring agent, concentrated sulfuric acid has been selected after comparing the liquefaction effect of different acid catalysts; to proceed the liquefaction experiment of lab-synthesized Particleboards and recycled useless Particleboards; according to analyze the factors in the process of liquefaction, two optimum Particleboard liquefaction technologies have been settled by orthogonal experiment; according to take the reaction between the two Particleboard liquefaction products and formaldehyde in the alkaline condition, heat convertible Particleboard liquefaction resin has been produced and the effective factors and technology of the resinification process has been studied, as well as comparative analysis of resin basic characters, two optimum resinification synthesis technologies of Particleboard liquefaction product have been settled by orthogonal experiment. The liquefied resin structure, performance characterization has been analysed by many methods of instrumental analysis: SEM, FTIR, 1H-NMR and 13C-NMR, DTA; further comparative analysis of compression strength and hydrolytic resistance has been studied on the molding materials made by the two Particleboard liquefied products. The conclusions as follow:(1) According to the residue ratio of hydro-thermal treatment of lab-synthesized Particleboards and recycled useless Particleboards and infrared spectrum analysis, the optimum hydro-thermal treatment condition is, lab-synthesized Particleboards: temperature 80℃, time 6 hrs; recycled useless Particleboards: 80℃, time 8 hrs.(2) In the process of the two Particleboards liquefaction in phenol, four inorganic acids: boric acid (crystal), hydrochloric acid (37%), phosphoric acid (85%), concentrated sulfuric acid (98%), liquefaction efficiency index includes residue ratio after liquefaction and free phenol in liquefaction product, the catalytic performance of sulfuric acid on Particleboard liquefaction in phenol is better comparatively, which accomplish Particleboard liquefaction in phenol in set temperatures, the catalytic performance of phosphoric acid is better than hydrochloric acid and boric acid, but no ideal liquefaction effect at all. the catalytic performance of hydrochloric acid is worse than phosphoric acid and sulfuric acid as its high volatility, more obvious in higher temperature. Boric acid is the worst as well as its weak acidity; Particleboard doesn't react in phenol even at 180℃and 10% catalyst usage, very low liquefaction efficiency.(3) To analyze the impact of different catalysts and their quantities on Particleboard liquefaction by residue crystallinity, higher residue crystallinity means better catalytic effect in the Particleboard liquefaction reaction, as the same as liquefaction efficiency evaluation in the same liquefaction condition, which based on the quantity of free phenol and residue ratio, the conclusion shows that sulfuric acid is the best catalyst for Particleboard.(4) Comparative ideal liquefaction technological parameters have been selected by the analysis of variance of experimental datum, it shows that, recycled useless Particleboard: liquefaction temperature at 140℃, liquefaction time 1.5 hrs, weight/solvent volume ratio (phenol/Particleboard powder): 4.5. 6% addition of sulfuric acid contributes the residue ratio down to 9.6%, the liquefaction efficiency is 90.4%, and the bromination content in liquefaction product is 43.48%. Lab-synthesized Particleboard: liquefaction temperature at 140℃, liquefaction time 1.5 hrs, weight/solvent volume ratio (phenol/Particleboard powder): 3.5. 6% addition of sulfuric acid contributes to 8.9% residue ratio, the liquefaction efficiency is 91.1%, and the bromination content in liquefaction product is 39.65%.(5) Orthogonal method has been adopted into resinification experiments, according to basic performance tests of resin under national standard and range analysis of resin's technology indexes, the optimum resinification technology of the two Particleboards has been confirmed. After verification test, two kinds of optimum resinification synthesis technology parameters of the two Particleboard liquefactions have been made. The optimum technology condition of recycled useless Particleboard is: resinification time 2 hrs, temperature at 85℃, the amount-of-substance ratio between formaldehyde and recycled useless Particleboard is 2.1, the amount-of-substance ratio between NaOH and recycled useless Particleboard is 0.6, the amount-of-substance ratio between water and recycled useless Particleboard is 9.0. The optimum technology condition of lab-synthesized Particleboard is: resinification time 2.5hrs, temperature at 90℃, the amount-of-substance ratio between formaldehyde and lab-synthesized Particleboard is 1.8, the amount-of-substance ratio between NaOH and lab-synthesized Particleboard is 0.5, the amount-of-substance ratio between water and lab-synthesized Particleboard is 9.0.(6) To analyze the process from the liquefaction products of the two Particleboards to resin, it is shown that granular wood substance in waste useless Particleboard liquefaction product is bigger than in lab-synthesized Particleboard liquefaction product. Liquefaction resins from the reaction of the two Particleboard liquefaction products and formaldehyde have the content of wood material, which never happens in general synthesis of phenol-formaldehyde resin. To compare the resins themselves, the shape of fibrous substance in waste useless Particleboard liquefaction product is bigger than in lab-synthesized Particleboard liquefaction product.(7) FTIR comparative analysis of the two Particleboard liquefaction resins and general phenol-formaldehyde resin shows that three kinds of resin have the similar absorption peak location, but different strength. The absorption peak locations of the two Particleboard liquefaction resins are higher than phenol-formaldehyde resin; namely, the functional group of the two Particleboard liquefaction resins has higher activity. (8) To compare the 1H-NMR spectrograms of the three resins and their spectrums, lab-synthesized Particleboard liquefaction product and waste useless Particleboard liquefaction product have the big content of lignin units; it shows that in the process of resinification, lignin has joined the copolycondensation reaction. To compare the nuclear magnetic spectrums of the two liquefaction resins, there aren't many differences, in other words, the resin structures of the two Particleboard liquefaction products are similar, and the differences of the radical content are coming from different chemical components in the two Particleboard liquefaction products.(9) According to compare the 13C-NMR spectrums of the two Particleboard liquefaction resins with general phenol-formaldehyde resin, the two resins contain both o,o Ph-CH-Ph, p,p Ph-CH-P and many lignin units, because in the resin synthesis process, lignin has joined the copolycondensation reaction with phenol and formaldehyde, and the polycondensation of phenol unit itself; there is no free phenol appears in general phenol-formaldehyde resin chemical shifts of free phenol in the other two resins, free phenol hasn't reacted completely in liquefaction products. To compare the spectrums of the two Particleboard liquefaction resins, there is a little difference; it states that the resin structures of the two Particleboard liquefaction products are similar, but different in the content of radical content.(10) The curing temperature of general phenol-formaldehyde resin is lower than waste useless and lab-synthesized modified phenol-formaldehyde resin; the thermal behavior of phenol resin from waste useless Particleboard liquefaction product is between general phenol-formaldehyde resin and lab-synthesized resin. As the temperature rises from 5℃/min to 20℃/min, the exothermic peak moves toward high temperature gradually and the diversity of the exothermic peak location is getting bigger and bigger, it shows that different test conditions have great impacts on thermal behavior.(11) To compare the one-factor analysis of molding time, molding temperature and the usage of wood powder and the mechanical properties of the liquefaction resin molding material, the optimum liquefaction product molding technology parameter as follow, molding time: 2 hrs, molding temperature: 120℃, the ratio of wood powder and resin: 1:1. To compare ultimate water absorption rate, water absorption thickness expansivity, ultimate volume expansivity and 24hrs water absorption expansivity between liquefaction resin molding material and phenol resin molding material, it is found that the former has better water resistance, the ultimate volume expansivity of waste Particleboard liquefaction resin molding material and lab-synthesized liquefaction resin molding material doesn't change much, 7.3% and 7.5% respectively; the ultimate water absorption rate are 29.6% and 31.2%; the water absorption thickness expansivity are 4.1% and 3.3%, 24hrs water absorption expansivity are 13.3 and 14.5%.(12) The raw material cost of waste useless Particleboard liquefaction resin is lower about 14.2% than general phenol-formaldehyde resin, which is 695.47 yuan per ton. Even electrical energy and water are needed in the process of waste Particleboard recycling, previous hydro-thermal treatment and liquefaction, the required temperature of resinification and hot press is lower than general phenol-formaldehyde resin, so based on comparative considering, to waste useless Particleboard liquefaction resin has the priority on cost. Furthermore, resource conservation, environment protection, the subsequent social benefit and ecological benefit has profound significance.
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