Study On The Reaction Of Isocyanate Solidified Splicing Wood

Based on the previous research works, this study investigated the bondability mechanism of isocyanate (IC) resin with wood. In thisdissertation, differential scanning calorimetry (DSC) was used to study the reaction rules of Poly methylene polyphenyl isocyanate (PAPI) with cellulose, lignin, mixture of cellulose and lignin, and wood, respectively. The results indicated that the reaction rate of IC with lignin and wood, respectively, was faster than that of IC with cellulose. The reaction rate of IC with the mixture of cellilose and lignin at different mixing ratios was close to that of IC with pure lignin. In the reaction process of IC with wood, the reaction rate was significantly influenced by the tridimentional inerratic structure of cellulose, while hydroxy showed lesseffect. With increasing moisture content (MC), the reaction rate of IC with cellulose and wood powder increased.This dissertation further discussed the reaction mechanism of Phenyl isocyanate (BMI) with lignin and wood power at different MC. The results showed that the reaction of IC with lignin was mainly determined by random nucleation mechanism, and all the reactions of IC with wood powder are dominated by surface-phasing mechanism, while its mechanical function was converted due to the influence of water. In addition, the mechanical parameter of reaction was calculated from the experimental data. It is concluded that the reaction rate of IC with lignin was faster than that of IC with wood powder; and the activation energy of lignin had the lowest value.The structures of the chemicals from the reaction of IC with wood and wood components were examined using Fourier Transform Infrared Spectroscopy (FTIR). The results indicated that carbamate was the major yielding product from the reaction of IC with ligrin. A little amount ofcarbamide was produced as lignin contained some water. However, the reaction of IC with wood powder produced a small amount of carbamate; and carbamide was the major product from the reaction of IC with wood powder at a certain MC.In addition, this research work studied the reaction of IC with cellulose, mixture of cellulose and lignin, and wood powder during hot pressing. The structures and contents of the yielding products from the reactions were also analyzed using FTIR and N-content method. It showed that all the reactions were affected by different hot pressing conditions.Finally, the bonding strength of IC resin and wood under hot pressing was tested. The relationship between bonding strength and reaction degree was analyzed.