Decay resistance of densified ammonia-plasticized stems of oil palm (Elaeis guineensis)
IRG/WP 3673
A H H Wong, M P Koh
When wafers of oil palm stems (Elaeis guineensis) were plasticized with 28% aqueous ammonia and immediately compressed mechanically, the treated material, gained 73% in basic density (average basic density, 0.695 g/cm³), and was highly resistant to decay by wood rot basidiomycetes. Compared with the control specimens (density, 0.403 g/cm³), resistance to decay of the densified specimens by Coriolus versicolor increased by 55%, and Gloeophyllum trabeum, 74%. Fungal decay was significantly correlated with basic density (densification effect) (r-value, between -0.77 and -0.92), mediated in part by a similar pattern of correlation (-0.86) between densification and decaying tissue moisture content. Mass losses of specimens which were plasticized but not subsequently densified, did not differ significantly (P<0.05) from the controls while basic density of such treated specimens decreased slightly (density, 0.358 g/cm³). Total nitrogen contents for the controls, specimens plasticized without densification, and densified plasticized specimens were respectively; 0.24, 0.65 and 0.63% (g/g), the control differing significantly from the rest. Substrate pH were similar among the three samples. It appeared that artificial densification (rather than total nitrogen levels) assumed an overriding influence on decay resistance of compressed ammonia-plasticized oil palm stems