flammability high strength high modulus and also maintain their integrity at high temperatures polyester fibers have high strength and are resistant to shrinking and stretching nylon fibers also have high strength toughness and abrasion resistance rayon is composed of regenerated cellulose and can be formed into high strength fibers having a good hand and good aesthetic characteristics cotton is also strong and has excellent absorbency wool on the other hand blends well with both synthetic and other natural fibers to form a blend having good tensile strength while polyester nylon rayon cotton and wool are economical constituents of the blend that have been found particularly suitable for blending with modacrylic staples other synthetic polymers may also be suitably blended with the modacrylic staples the choice of one or more staple fibers to blend with the modacrylic staples depends upon other non flame resistant properties desired in the finished fabric and apparel including hairiness and hand strength flexibility absorbency etc as is conventional in staple yarn manufacture bales of staple fibers in the percentages described above are initially subjected to an opening process whereby the compacted fibers are u201c pulled u201d or u201c plucked u201d in preparation for carding opening serves to promote cleaning and intimate blending of fibers in a uniform mixture during the yarn formation process those skilled in the art will appreciate that there are a number of conventional hoppers and fine openers that are acceptable for this process the open and blended fibers are next carded using marzoli cx300 cards to form card slivers the card slivers are transformed into drawing slivers through a drawing process utilizing a process known.