Novel elastomeric polyurethane fibers modified with polypropylene microfibers

• Blends of polypropylene (PP) and thermoplastic polyurethane (TPU) were studied.
• Blending in a mixer produced generally globular PP in the TPU matrix.
• Extrusion caused fibrillation of PP both with and without compatibilizer.
• PP microfibers with diameters from 200 to 800 nm were highly oriented.
• Compatibilizer improved tensile strength, modulus and elastic recovery of blends.

Extrusion of immiscible polymer biphasic blends to form in situ microfibers of the minor component in the matrix of the major component is an elegant way to create composites with new properties. The process was used to obtain thermoplastic polyurethane elastomers modified with polypropylene microfibers. The effect of phase interaction on blend morphology and properties was studied by running a series of blends with and without a maleated polypropylene compatibilizer. Six different blends were prepared: three with compatibilizer and three without the compatibilizer. All blends contained polypropylene as a minor component (80/20; 90/10 and 95/5). Extrusion spinning of polyurethane/polypropylene blends with and without compatibilizer resulted in polyurethane fibers modified with highly-oriented polypropylene microfibrils at all component ratios. Increasing polypropylene concentration in the thermoplastic polyurethane matrix increased hardness and modulus, but did not affect tensile strength and lowered elastic recovery.

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