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In this work, tea powder was used as a filler to produce low-formaldehyde-emission tea-based melamine-modified urea–formaldehyde resin (TMUF). The thermal stabilities of TMUF and the resin without tea powder (MUF0) were characterized using thermogravimetry. The optimal amount of tea powder m(tea)/m(tea + urea) was equal to 0.15. The formaldehyde emission of the three-layer plywood produced by TMUF was reduced by 75.43%, and the wet bonding strength of the plate was increased by 26.67% as compared with the plywood prepared by MUF0. Compared with MUF0, the thermal degradation peak temperature of TMUF resin was shifted to higher temperature, while the carbon residue was increased. The thermal degradation activation energies of TMUF and MUF0 were similar, while TMUF had a lower pre-exponential A. The Flynn–Wall–Ozawa model-free method is used to estimate various activation energy values at different conversion rates and to predict possible reaction mechanisms. Judging the reaction mechanism according to the slope of the straight line fitted by different models, the best model was based on random nucleation. [ABSTRACT FROM AUTHOR]

The thermal decomposition characteristics of microwave liquefied rape straw residues with respect to liquefaction condition and pyrolysis conversion were investigated using a thermogravimetric (TG) analyzer at the heating rates of 5, 20, 50 °C min−1. The hemicellulose decomposition peak was absent at the derivative thermogravimetric analysis (DTG) curve of liquefied residues, because it had been decomposed during the liquefaction. Furthermore, among the liquefied residues, the one from the reaction condition of 180 °C/15 min had the highest thermal stability under a high temperature (>700 °C). The DTG profiles revealed that raising the temperature heating rate could result in an increase in the maximum decomposition temperature. The apparent activation energy (Eα) values of the liquefied residues were lower than that of non-liquefied raw rape straw, whereas the recondensation reaction occurred at 180 °C/15 min remarkably increased the Eα. A noticeable increase in the Eα was observed for the liquefied residue from the 180 °C/10 min samples as the pyrolysis conversion increased from 0.15 to 0.55, suggesting a complex decomposition process with the increasing pyrolysis temperature. The liquefaction process could decrease the thermal decomposition temperature of biomass, which means higher reactivity and lower operational costs during pyrolysis. [ABSTRACT FROM AUTHOR]