Fibers of blends with liquid-crystalline polymers: Spinnability and mechanical properties

Several blends of flexible polymers (PET, PC, Nylon-6, PP) with wholly aromatic or semi-aromatic liquid crystalline polymers (LCPs) were spun under different conditions and their melt viscosities, their spinnability (evaluated through the melt strength, MS, and the breaking stretching ratio, BSR), and their mechanical properties were studied The measured MS and BSR values of some of the blends were found to be higher than expected on the basis of the viscosity reduction brought about by the LCP minor phase, and were interpreted as being the result of good phase compatibility in the molten state. The fiber mechanical properties were appreciably enhanced over those of neat polymers only when good spinnability (granting LCP droplets fibrillation, and orientation of the matrix polymer) was accompanied by sufficient interphase adhesion in the solid state.