Improvements in preventing heat- and moisture-shrink problems in specific polypropylene tape fibers are demonstrated herein. Such fibers are manufactured through the initial production of polypropylene films or tubes which are then slit into very thin, though flat tape fibers thereafter. Such fibers include rigidifying nucleating compounds that nucleate polymer crystals within the target polypropylene after exposure to sufficient heat to melt the initial pelletized polymer and upon allowing such a melt to cool. Specific methods of manufacture of such inventive tape fibers, as well as fabric articles made therefrom, are also encompassed within this invention.