木质素
纤维素
焊接
结晶度
降级(电信)
糠醛
聚合物
碳-13核磁共振
化学
材料科学
脱水
化学工程
有机化学
高分子化学
复合材料
电信
计算机科学
工程类
催化作用
生物化学
作者
Luc Delmotte,Christelle Ganne‐Chèdeville,Jean-Michel Leban,A. Pizzi,Frédéric Pichelin
标识
DOI:10.1016/j.polymdegradstab.2007.11.020
摘要
The essential chemical modifications involving the polymeric constituents of wood in friction welding occur in the first 5–6 s slowing down or even stopping afterwards. FT-IR and CP-MAS 13C NMR of the welded area of wood have shown dehydration and an apparent increase in the crystallinity of cellulose. A certain level of hemicelluloses degradation occurs, accompanied by the generation of some furfural. Cellulose degradation is instead very slight. Both analytical techniques show an increase in the proportion of lignin in the welding interphase. A proportion of methoxy groups of lignin is de-etherified to phenolic hydroxy groups. Self-condensation of lignin occurs by internal rearrangement with the formation of Ar–Ar and Ar–CH2–Ar bridges. This progresses throughout the whole process of welding. The formation of C–O–C bridges, although stopping after 6 s welding, at the start of wood carbonisation, also appears to contribute to the increase in cross-linking of the lignin network.
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