Chemical Retting of Flax Straw Under Alkaline Conditions

Abstract

More controllable retting procedures to produce quality fibers from flax are sought by applying chelators at high pH and enzyme chelating formulations at lower pH. Using the Fried Test as an in vitro method for evaluating fiber separation from shive, EDTA (ethylenediaminetetraacetic acid) at 8 mM levels and sodium tripolyphosphate at 50 mM levels, both with 25 mM NaOH, effectively ret flax stems. Sodium gluconate, trisodium phosphate, and sulfuric acid are ineffective as retting agents. In 50 g laboratory scale retting trials, chemical retting at high pH with EDTA or sodium tripolyphosphate produces fine fiber yields (as produced through the Shirley Analyzer) that are about half that with enzyme chelator formulations; fibers are coarser with chemical versus enzyme retting. Chemical retting is influenced by chelator type and level, sodium hydroxide levels, and plant condition and maturity. These factors plus resultant fiber properties require consid eration when optimizing chemical retting with chelators at high pH.