The Relationship Of Extractive Content To Particle Size Distribution In Milled Yellow-Poplar (<i>Liriodendron Tulipifera</i> L.) Bark


  • Steven P. Ottone
  • R. C. Baldwin


Tulip-poplar, bark, anatomy, particle size, extractives, SEM, porosimetry


A method of separating milled yellow-poplar (Liriodendron tulipifera L.) bark into five sieve fractions containing representative inner and outer bark, cells, tissues, and fragments was developed. Anatomical composition of the fractions was examined by light microscopy. Each fraction was sequentially extracted with ether, ethanol-benzene, hot water, and cold water to investigate the relationship between the extractive content and the anatomical composition of the fraction. A statistically significant relationship was found between the amount of extractive and the particle size distribution of material in each fraction. Additionally, extractive content was found to be dependent not only on the absolute amount of bark retained but also on the relative amounts of inner and outer bark in each fraction. Total extractive content was found to increase with decreasing particle size. Examination of SEM micrographs following each stage in the extraction process revealed sequential changes to cell structure. The magnitude of the changes appeared to be closely related to the amount of extractive recovered in each fraction. Changes in porosity and void volume, as an indication of the removal of extractives by fraction, were investigated with a mercury porosimeter. Data indicated significant and sequential changes in porosity and void volume following extraction.


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