Separation of Fiber and Shivesfrom Decorticated Flax

Abstract

Decorticated flax contains a significant amount of shive, which limits applications of flax fiber. Separation of shive from flax fiber is essential to improve the resulting product‘s quality. The intention of this study was to use the pneumatic method for separation of flax fiber from shive. Differences between the terminal velocities of flax fiber and shive particles were investigated to assess the viability of the pneumatic method to separate these particles. Individual fiber and shive particle properties were measured and characterized vis-a -vis their width, length, mass, and terminal velocities. A generic fiber sorter was used for the sorting tests with two types of decorticated flax fibers as treatments: Grades 1 and 2 having initial fiber purity (i.e., content) of 51% and 15%, respectively. The results of the pneumatic tests showed that the length of fiber particles did not influence the terminal velocities of fiber. For shive content, an increase in mass and width showed an increasing trend in terminal velocity. The ranges of terminal velocities for shive and fiber particles were 1.22 to 4.10 m s-1 and 0.41 to 1.14 m s-1, respectively, which were significantly different. The results of the sorting tests showed that the sorting method resulted in the fiber purity of approximately 80% for Grade 1 and 66% for Grade 2, which was a significant improvement when compared to their initial purities. This study demonstrated the potential of pneumatic and sorting methods for improving fiber quality.