高含水率状态下桦木与异氰酸酯的胶接化学反应历程

doi:10.3969/j.issn.0253-2417.2014.01.006

Chemistry and Industry of Forest Products ›› 2014, Vol. 34 ›› Issue (1): 31-36.doi: 10.3969/j.issn.0253-2417.2014.01.006

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The Chemical Reaction Process of Bonding Birch with Isocyanate at the Condition of High Moisture Content

WEI Shuang-ying^1,2,3, LI Cun-lu², WANG Di^1,2, GU Ji-you^1,2, CAO Jun³

1. Key Laboratory of Bio-based Material Science and Technology, Northeast Forestry University, Harbin 150040, China;
2. Material Science and Engineering College, Northeast Forestry University, Harbin 150040, China;
3. Postdoctoral Research Station in College of Mechanical and Electrical Engineering, Northeast Forestry University, Harbin 150040, China

Received:2013-07-14 Online:2014-02-25 Published:2014-03-05

Abstract

Abstract: The bonding mechanism of birch in high moisture content glued with moisture curing isocyanate adhesive was investigated in this paper. The reaction processes between isocyanate groups (—NCO) in glued systems and free water or hydroxyl (—OH) in different chemical environment of birch were simulated using DMol3 program of Material Studio software. The difficulty and order of reaction were determined by searching the transition state and computation of the activation energy and the total energy of reaction. The investigations showed that the activation energy of reaction between —NCO groups and free water was closed to that between —NCO groups and —OH of cellulose. This indicated that these were a couple of competitive reactions. The reaction between —NCO and —OH of cellulose in the glued system occurs relatively easier than the reaction of —NCO and —OH of lignin. Furthermore, the order of reaction in cellulose is C₆ >C₃ >C₁ >C₂ and all of reactions in cellulose are exothermic. The order of reaction in lignin is lilac propane (Lig-S)> guaiacyl propane (Lig-G)>p-hydroxyphenyl propane (Lig-H). The reactions of Lig-S and Lig-G are exothermic, but the reaction of Lig-H was an endothermic reaction.

Key words: high moisture content, density function theory, isocyanate groups, bonding mechanism

CLC Number:

TQ35

WEI Shuang-ying, LI Cun-lu, WANG Di, GU Ji-you, CAO Jun. The Chemical Reaction Process of Bonding Birch with Isocyanate at the Condition of High Moisture Content[J]. Chemistry and Industry of Forest Products, 2014, 34(1): 31-36.

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The Chemical Reaction Process of Bonding Birch with Isocyanate at the Condition of High Moisture Content

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