Significance of acid and heat treatment on non-conventional bonding of gian ipil-ipil (Leucaena leucocephala)
2000
Mari, E.L. (Forestry Products Research & Development Institute, Laguna 4031 (Philippines)) | Kiguchi, M. | Suzuki, M.
Chemical treatments, which induce changes in wood to make it self-bonding, are essential in non-conventional bonding. In this study, chemical changes in wood due to nitric acid and heat treatments were analysed to elucidate the mechanisms involved in the formation of bonds. Electron Spectroscopy for Chemical Analysis spectra showed that the treatments caused an increase in carbonyl (C3) fraction which represents bonds due to some insoluble acids in wood. The increase in the amount of insoluble acids was high in the early stages of heating but decreased with longer heating times suggesting decarboxylation. In comparison, soluble acids decreased progressively with heating. Infra-red spectral analysis confirmed that heating used up or reduced unreacted acids. Slight increases in lignin content after heating suggested partial resinfication of degraded wood components. From the above mentioned mechanism, composite boards produced from milled wood rich in water-soluble fraction had superior qualities in modulus of rupture and thickness swelling.
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