In this study, alkaline lignin (AL), dealkaline lignin (DAL), and lignin sulfonate (SL) were liquefied in phenol with sulfuric acid (H2SO4) or hydrochloric acid (HCl) as the catalyst. The phenol-liquefied lignins were used as raw materials to prepare resol-type phenol-formaldehyde resins (PF) by reacting with formalin under alkaline conditions. The results show that phenol-liquefied lignin-based PF resins had shorter gel time at 135 degrees C and had lower exothermic peak temperature during DSC heat-scanning than that of normal PF resin. The thermo-degradation of cured phenol-liquefied lignin-based PF resins was divided into four temperature regions, similar to the normal PF resin. When phenol-liquefied lignin-based PF resins were used for manufacturing plywood, most of them had the dry, warm water soaked, and repetitive boiling water soaked bonding strength fitting in the request of CNS 1349 standard for Type 1 plywood. (c) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 201

No abstract

Taiwan acacia (Acacia confusa) and China fir (Cunninghamia lanceolata) were liquefied in polyethylene glycol (PEG)-glycerol cosolvent, with sulfuric acid (H 2 SO 4 ) as a catalyst. The liquefied woods were blended with three kinds of isocyanate, such as poly-4,4 0 -diphenylmethane diisocyanate (PMDI), Desmodur L (adduct of toluene diisocyanate with trimethylol propane), and Desmodur N (trimer of hexamethylene diisocyanate), to prepare polyurethane (PU) resins. From the results, China fir had better liquefaction effect than Taiwan acacia. Those PU resins prepared from liquefied wood blending with isocyanate could cure at room temperature. Their gel property was influenced by the type of isocyanate, the molar ratio of the functional group of isocyanate to liquefied wood [NCO/ (OH1COOH)], and the rate of catalyst added. PU resins prepared from Desmodur L had an appropriate gel time for processing. But those prepared from PMDI had too short gel time to process. Contrary, the PU resins prepared from Desmodur N would take a longer time to gel. However, addition of catalyst could shorten the gel time significantly. FT-IR analysis showed that a urethane bond had formed between the liquefied wood and isocyanate. When these PU resins were used as wood adhesives, liquefied wood blended with Desmodur L had better dry and wet bonding strength than others. Increasing the molar ratio of NCO/(OH1COOH) could increase the bonding strength. On comparing liquefied Taiwan acacia and China fir, the former had better bonding strength than the latter.

No abstract

Barks of Taiwan acacia (Acacia confusa) and China fir (Cunninghamia lanceolata) were liquefied in the presence of phenol with sulfuric acid (H 2 SO 4 ) and hydrochloric acid (HCl) as catalyst. The properties of resins prepared from liquefied bark and the feasibility of liquefied bark-based resol resins in particle board manufacturing were investigated. The viscosity and thermosetting property of liquefied bark-based resol resins were affected by the kind of bark species and the catalyst used. Liquefied bark-based resol resins using China fir bark as raw material had higher viscosity than the ones using Taiwan acacia bark. In the course of thermosetting, liquefied bark-based resol resins using Taiwan acacia bark as raw material had a higher maximum temperature of exothermic peak and onset temperature as well as a larger quantity of exothermic heat than those using China fir bark. Resol resins prepared from bark liquefied with H 2 SO 4 as catalyst had higher viscosity, while resins with HCl as catalyst had a higher maximum temperature and height of exothermic peak and a larger quantity of exothermic heat at thermosetting. Particle board made with A-S adhesive that was prepared from liquefied Taiwan acacia bark with H 2 SO 4 as catalyst had the best particle board properties than those made with other adhesives. For the particle board made with A-S adhesive, its static bending strength and internal bonding strength would be increased as the hot-pressing time extended. The particle board made with hot-pressing temperature of 150°C and hot-pressing time of 10 min had the maximum normal and wet static bending strength and internal bonding strength. Its normal static bending strength was 170.8 kgf/cm 2 and the particle board showed satisfactory wet static bending strength and internal bonding strength.