About distinguishing non-woven materials

1. Hand visual inspection method: This method is suitable for non-woven materials in loose fiber state. (1) Cotton fiber is shorter and thinner than ramie fiber and other hemp fiber and wool fiber, and it is often accompanied by various impurities and defects. (2) The hemp fiber feels rough and hard. (3) The wool fiber is curly and elastic. (4) Silk is long and slender, with special luster. (5) Among chemical fibers, only viscose fibers have a large difference in strength between dry and wet states. (6) Spandex yarn has very large elasticity, and its length can be stretched to more than five times at room temperature. 2. Microscopic observation method: It is to identify the non-woven fabric fiber according to the longitudinal and cross-sectional morphological characteristics of the fiber. (1) Cotton fiber: cross-sectional shape: round waist with middle waist; longitudinal shape: flat ribbon shape with natural twist. (2) Hemp (ramie, flax, jute) fiber: cross-sectional shape: round or polygonal waist, with a middle cavity; longitudinal shape: horizontal nodes, vertical lines. (3) Wool fiber: cross-sectional shape: round or approximately round, some with pith; longitudinal shape: scales on the surface. (4) Rabbit hair fiber: cross-sectional shape: dumbbell-shaped with hair pith; longitudinal shape: scales on the surface. (5) Mulberry silk fiber: cross-sectional shape: irregular triangle; longitudinal shape: smooth and straight, with stripes longitudinally. (6) Ordinary viscose fiber: cross-sectional shape: zigzag, skin-core structure; longitudinal shape: longitudinal grooves. (7) Rich and strong fiber: cross-sectional shape: less tooth shape, or round or oval; longitudinal shape: smooth surface. (8) Acetate fiber: cross-sectional shape: trilobal or irregular zigzag shape; longitudinal shape: longitudinal stripes on the surface. (9) Acrylic fiber: cross-section shape: round, dumbbell or leaf shape; longitudinal shape: smooth or striped surface. (10) Chlorine fiber: cross-sectional shape: close to circular; longitudinal shape: smooth surface. (11) Spandex fiber: cross-sectional shape: irregular shape, round, potato-shaped; longitudinal shape: dark and deep surface, showing unclear bone-shaped stripes. (12) Polyester, nylon and polypropylene fibers: cross-sectional shape: round or special shape; longitudinal shape: smooth. (13) Vinylon fiber: cross-sectional shape: round waist, skin-core structure; longitudinal shape: 1 to 2 grooves. 3. Density gradient method: Identify non-woven fibers based on the characteristics of various fibers with different densities. (1) To prepare the density gradient liquid, generally choose the xylene carbon tetrachloride system. (2) For the calibration of density gradient tubes, the precision ball method is commonly used. (3) Measurement and calculation. The fiber to be tested is pretreated by deoiling, drying, and defoaming. After making a small ball into the balance, the fiber density is measured according to the position of the fiber suspension. 4. Fluorescence method: Use ultraviolet fluorescent lamp to irradiate non-woven fabric fiber, and identify non-woven fabric fiber according to the different luminous properties of various non-woven fabric fibers and different fluorescent colors of non-woven fabric fibers. The fluorescent colors of various non-woven fibers are shown in detail: (1), cotton, wool fiber: light yellow (2), mercerized cotton fiber: light red (3), jute (raw) fiber: purple-brown (4), jute , Silk, nylon fiber: light blue (5), viscose fiber: white purple shadow (6), light viscose fiber: light yellow purple shadow (7), polyester fiber: white light blue sky light is very bright (8), Vinylon has light fiber: light yellow purple shade. 5. Combustion method: According to the different chemical composition of the non-woven fiber, the combustion characteristics are also different, so as to roughly distinguish the major types of non-woven fibers. The burning characteristics of several common non-woven fibers are as follows: (1) Cotton, linen, viscose, cupra: close to the flame: no shrinkage and no melting; contact with the flame: rapid burning; leaving the flame: continuing to burn; smell : The smell of burning paper; the characteristics of the residue: a small amount of gray-black or gray-white ashes. (2) Silk and wool fibers: close to the flame: curl and melt; in contact with the flame: curl, melt, burn; leave the flame: slow burning and sometimes extinguish itself; smell: the smell of burnt hair; residue characteristics: loose and brittle black particles Or coke-like. (3) Polyester fiber: close to the flame: melting; touching the flame: melting, smoking, slowly burning; leaving the flame: continue to burn, sometimes extinguished by itself; smell: special aromatic sweetness; residue characteristics: hard black round beads . (4) Nylon fiber: near the flame: melting and shrinking; contacting the flame: melting and smoking; leaving the flame: self-extinguishing; smell: amino smell; residue characteristics: hard light brown transparent round beads. (5) Acrylic fiber: close to the flame: melting; contacting the flame: melting and smoking; leaving the flame: continuing to burn and emitting black smoke; smell: pungent; residue characteristics: black irregular beads, fragile. (6) Polypropylene fiber: near the flame: melting; contacting the flame: melting and burning; leaving the flame: continuing to burn; smell: paraffin smell; residue characteristics: off-white hard transparent round beads. (7) Spandex fiber: close to the flame: melting and shrinking; contacting the flame: melting and burning; leaving the flame: self-extinguishing; smell: peculiar smell; residue characteristics: white gel. (8) Chlorine fiber: near the flame: melting; contacting the flame: melting, burning, black smoke; leaving the flame: self-extinguishing; smell: pungent smell; residue characteristics: dark brown lumps. (9) Vinylon fiber: close to the flame: melting; contacting the flame: melting and burning; leaving the flame: continuing to burn, emitting black smoke; smell: unique fragrance; residue characteristics: irregular scorched brown lumps.