CP-MAS C NMR and FT-IR investigation of the degradation reactions of polymer constituents in wood welding |
| |
Authors: | L Delmotte C Ganne-Chedeville JM Leban F Pichelin |
| |
Institution: | a L.M.P.C, ENSCMu, University of Haute Alsace, Mulhouse, France b ENSTIB, University of Nancy 1, 27 rue du Merle Blanc, 88000 Epinal, France c HSB, Fachhoschule für Architektur, Bau und Holz, Biel, Switzerland d LERFOB, INRA, Centre de recherche de Champenoux, Champenoux, France |
| |
Abstract: | 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. |
| |
Keywords: | Degradation reactions Wood constituents Wood welding Thermal degradation NMR FT-IR |
本文献已被 ScienceDirect 等数据库收录! |
|