Drafting dynamics of fine denier polyester fibers

In synthetic fibers, the influence of the fiber fineness and its interaction with the roller drafting process has not been thoroughly studied because controlling of other fiber properties could be difficult. This study was aimed at illuminating the effect of fiber fineness on drafting. In this research, the three different fiber fineness used were 0.8, 1.0 and 1.2 denier. In order to monitor the fineness effect, fibers and slivers were produced almost identically except in fineness.; In the first experiment, static cohesion properties of three finenesses were tested. During this test, card sliver stretched until it was torn apart. The microfiber slivers were found to be slightly different from the card slivers of 1.0 and 1.2 denier fibers.; The second experiment measured the dynamic cohesion force of a single sliver at different roller speeds by using a Rothschild Cohesion Meter. The cohesion force of regular fibers increased with increasing roller speed while microfibers had a decreasing trend at the same delivery speeds.; Movements of fibers in the three over three roller drafting system were investigated by using a high-speed camera, which allowed direct observations of randomly chosen fibers as they pass through the drafting zones. Results showed that fineness influenced the acceleration of fibers. Microfibers had higher average speed but the 1.2 denier fibers usually had higher variation in speed. A different local acceleration of fibers may indicate that a clustering formation in the card sliver caused different drafting behavior for different fiber fineness in the various draft combinations and roller settings. Results from drafting force in the break and main drafting zones showed significant differences between finenesses. Drafting force in the break drafting zone had a curvilinear relationship with break drafting ratio. In the main drafting zone, each fiber fineness had different magnitude of friction force at different drafting conditions. Sliver irregularity, which was measured as fibers were coming out of the drafting zone, highly depended on fiber fineness and drafting conditions.; Previous theories have assumed that all fibers entering the drafting zone were straight and parallel to the sliver axis with a random distribution. However, video recordings and the results from drafting force experiments revealed that clustering effect might be a crucial factor for dynamics of drafting.; High-levels of fiber entanglement in card sliver and fiber fineness both increased cluster formation in the sliver. Since the bending rigidity is dependent on the fiber diameter, finer denier fibers are more flexible than regular fibers. This may result in an increasing number of clusters and fiber contact points.