Characterization of radio frequency assisted water retting and flax fibers obtained

• RF treatment enhanced the retting efficiency of flax straws.
• RF treatment improved the whiteness, greenness and blueness of fibers slightly.
• RF treatment changed the tensile properties of flax fibers.
• RF treatment should be different for flax in different stages of water retting.
• The way RF functioned is a combined effect.

Water retting used to degrade pectin in the bast of plant, release and separate fibers normally takes one to two weeks. In this study, radio frequency (RF) was introduced to enhance the retting efficiency in different stages of water retting, and different RF treatment temperatures and durations were used. The pectin loss in phloem part of the RF-treated flax straws, defined as degumming rate, was measured to evaluate retting efficiency besides Fried test. The color, linear density and tensile properties of the resulting fibers were measured. The relationships between retting results and process parameters were established using the response surface methodology, and the way RF functioned in retting process was studied. It was found that RF best improved retting quality of the 2-day, and 6- and 10-day water retting at 40 °C and 90 °C for 60 min, respectively.