EFFECTS OF EXTRACTION ON YIELDS AND CHARACTERISTICS OF BARK EXTRACTS

To develop adhesives or adhesive extenders from barks, five different southeastern tree barks: southern pine (Pinus taeda); sweetgum (Liquidambar styraciflua); white oak (Quercus alba); red oak (Quercus falcata); and yellow poplar (Liriodendron tulipifera); were obtained from sawmills in Georgia. The chemical analysis of barks was first carried out to examine their compositions. Air dried barks were ground with a hammer mill and then treated and/or extracted with various solutions at different levels of concentration and temperature. Approximately eighty different kinds of bark products were produced from the combination of these treatments. The yields and solubility, as well as contents of polyphenol and organic substances in extracts were determined for each treatment. The highest yield of bark extracts was obtained from sodium hydroxide extraction. The sodium carbonate extraction yielded the lowest amount and the extracts jelled in a few days at room temperature.