334 16.From Natural Fibers to Man-Made Plastics HOOL 4.0KU x286824mm X2500 (a) (b) 度K X58 39m前 (c) (d) FIGURE 16.2.Scanning animal fibers (except silk)are covered with an outer layer of electron micrographs unidirectional overlapping scales,as depicted in Figure 16.2(a). of (a)wool fiber(note Mechanical action in conjunction with heat and moisture the scales on the sur- causes the fibers to slide past each other and interlock.Felt is face that overlap each other;the tips point to widely used in the hat industry and for making slippers and the free end of the polishing materials. hair),(b)silk fibers Silk is spun by the larva of Bombyx mori,as was mentioned (note the thin syn- in Section 16.1.The proteins of silk contain about 80%fibroin thetic fiber that has (which makes up the filament)and about 20%sericin or silk gum been smuggled in),(c) (which holds the filaments together).Minor constituents are plant fiber at low mag- waxes,fats,salts,and ash.Silk is a continuous fiber,that is,it nification,and (d) has no cellular structure.The life cycle of Bombyx mori includes plant fiber at high hatching of the disk-shaped eggs in an incubator at 27C,which magnification.(Cour- requires about 10 days.The"silkworm,"3 mm long and 3 mg in tesy of R.Crockett and mass,eventually grows into a 90-mm-long caterpillar which R.E.Hummel,MAIC, University of Florida.) needs five daily feedings of chopped,young mulberry leaves.Af-animal fibers (except silk) are covered with an outer layer of unidirectional overlapping scales, as depicted in Figure 16.2(a). Mechanical action in conjunction with heat and moisture causes the fibers to slide past each other and interlock. Felt is widely used in the hat industry and for making slippers and polishing materials. Silk is spun by the larva of Bombyx mori, as was mentioned in Section 16.1. The proteins of silk contain about 80% fibroin (which makes up the filament) and about 20% sericin or silk gum (which holds the filaments together). Minor constituents are waxes, fats, salts, and ash. Silk is a continuous fiber, that is, it has no cellular structure. The life cycle of Bombyx mori includes hatching of the disk-shaped eggs in an incubator at 27°C, which requires about 10 days. The “silkworm,” 3 mm long and 3 mg in mass, eventually grows into a 90-mm-long caterpillar which needs five daily feedings of chopped, young mulberry leaves. Af- 334 16 • From Natural Fibers to Man-Made Plastics FIGURE 16.2. Scanning electron micrographs of (a) wool fiber (note the scales on the sur￾face that overlap each other; the tips point to the free end of the hair), (b) silk fibers (note the thin syn￾thetic fiber that has been smuggled in), (c) plant fiber at low mag￾nification, and (d) plant fiber at high magnification. (Cour￾tesy of R. Crockett and R.E. Hummel, MAIC, University of Florida.) (c) (d) (a) (b)