Drawing behavior of polyblend fibers from polypropylene and liquid crystal polymers

Polyblend fibers were made from mixtures of polypropylene (PP) and thermotropic liquid crystal polymers (LCPs). The as-spun fibers were drawn to produce the oriented structure for the PP matrix. The LCPs were found to exist in thin and long fibrils in the as-spun fibers; after drawing, they were split into short fragments. From a simplified model whereby a single LCP fibril is embedded in a PP matrix fiber, it was calculated out that the length of the LCP fibril in the drawn fiber is directly proportional to the fibril diameter and tenacity, and is reversely proportional to the compressional stress on the fibril and the friction coefficient between the fibril and the surrounding matrix. With regard to the drawing conditions, it was found that a long length of the LCP fibrils can be preserved by increasing the drawing temperature, or by reducing the draw rate. The effect of two-stage drawing on the LCP phase morphology was also studied in the present work. © 1994 John Wiley & Sons, Inc.