Changes in Chemical Composition and Microstructure of Bamboo after Gamma Ray Irradiation

Abstract

Changes in bamboo composition and microstructure following 60 Co gamma (γ) ray irradiation were investigated by solid state 13 C crosspolarization (CP) magic-angle spinning (MAS) spectroscopic nuclear magnetic resonance spectrometry (NMR) and a field emission scanning electron microscope (FESEM). The results indicated that irradiation doses lower than 100 KGy resulted in the degradation of hemicelluloses via scission of molecular chains, but there was also repolymerization and condensation in lignin. Irradiation doses higher than 100 KGy resulted in the degradation of cellulose, hemicelluloses, and lignin by significant oxidation reaction and partial scission of biopolymer chains to yield more small fragments with carbonyl groups.

Changes in mechanical and chemical wood properties by electron beam irradiation

“…grinding in a micro-vibration mill) treatments the differences in irradiated wood structures can be observed. Also, the gamma irradiation doses up to 300 kGy did not change the structure of bamboo [7]. Therefore, in this study the analysis of the wood microstructure was not the main objective.…”

“…The results show that the relative crystallinity index did not change strongly, and that is in accordance with the results from X-ray diffraction analysis (Table 2). Also the results from other studies depicted that the crystallinity of cellulose is not significantly affected by gamma ray irradiation [7,27]. Nevertheless, Baccaro et al [28] and Charlesby [8] analysed the influence on the cellulose crystallinity of high ionising radiation.…”

“…The most important Calkyl O ether vibrations (methoxyl and b-O-4) were assigned to the 1047-1004 cm −1 region [40]. Also, Sun [7] concluded that the increase in methoxyl groups after a 100 kGy gamma ray irradiation indicates condensation reactions of lignin. All EBI treated samples showed positive FT-IR difference spectra in the range from 1200 to 800 cm −1 , which implies that a higher content of functional groups can be observed than in the reference measurements.…”

“…The results from Su et al [7] indicated that the cellulose and lignin contents of gamma irradiated bamboo were stable, whereas the holocellulose content decreased dramatically until irradiation doses was lower than 300 kGy. Therefore, the electron beam irradiation may alter the polyoses (hemicellulose) composition resulting in partial polymerisation of cellulose and lignin.…”

“…Ionising irradiation is one possible method to alter the wood properties [4][5][6][7]. The irradiated wood undergoes various changes in properties.…”