Effect of enzyme retting conditions on bast bundle differentiation and mechanical properties of flax technical fibers

Abstract

Compared to conventional dew retting, enzymatic retting has the potential to control fiber extraction process and produce high quality plant fibers for industrial scale composite applications where low Family videovariation in properties are desired. While most studies depend upon retting duration and fiber fineness as measures for effective retting degree, in this study we report the effect of enzyme concentration and enzyme retting duration on the flax bast-woody core bond strength and resulting technical fiber fineness. Fiber peel tests and microscopy coupled with statistical analysis showed that while only retting duration has significantly effect on fiber fineness, the bond strength between the bast-woody core interphase is significantly affected by both enzyme concentration and time. Single fiber tensile tests were conducted on flax fibers from different retting conditions at 10 mm and 30 mm gauge lengths. Fibers extracted from a high degree of enzymatic retting performed well at 10 mm gauge length but showed lower tensile strength at 30 mm gauge length, indicating over-retting. These findings can guide optimizing the enzyme retting process conditions at industrial scale for improved fiber properties with reduced variability.