The relation of lignin and polyphenol content of tasmanian alpine ash (Eucalyptus delegatensis R. T. Bak.) to shrinkage and recovery

Summary

Specimens of Eucalyptus delegatensis timber showing different degrees of shrinkage and recovery on reconditioning have been examined by staining and analysed for lignin and polyphenol content. Collapsed specimens did not stain normally for lignin but this was shown to be caused by masking of staining reactions by polyphenol. Cross sectional area shrinkage before reconditioning did not show any significant correlation with either lignin or polyphenol content but shrinkage after reconditioning showed highly significant negative correlation with lignin and polyphenol content. Amount of recovery showed positive correlation with both lignin and polyphenol content. It is clear that low lignin and low polyphenol content is associated with lack of recovery and that polyphenol does tend to promote recovery. No evidence could be found to support the hypothesis that the rheological properties of the collapse specimens were influenced by esterification of the lignin with extraneous substances causing blocking of the normal lignin-polysaccharide bonding. The evidence suggests that polyphenol acts only as a bulking agent.