Acrylic fibers stress-strain curve

Crazing. This develops in such amorphous plastics as acrylics, PVCs, PS, and PCs as creep deformation enters the rupture phase. Crazes start sooner under high stress levels. Crazing occurs in crystalline plastics, but in those its onset is not readily visible. It also occurs in most fiber-reinforced plastics, at the time-dependent knee in the stress-strain curve. 

FIGURE 12.44 Effect of temperature on stress-strain curve for acrylic fiber in dry medium (silicone oil). (From Rosenbaum, S., J. Appl. Polym. Sci. 9, 2071, 1965.)... 

A generalized stress-strain curve for an acrylic fiber is shown in Figure 17.16. 

The mechanical properties of acrylic fiber are deficient under hot-wet conditions. This is primarily due to the fact that the wet Tg of acrylonitrile copolymers is lower than the boiling point of water. Textile wet-processing must be carried out in such a way as to minimize yarn or fabric distortion. Shape retention and maintenance of original bulk under the lower temperatures in home laimdering cycles are acceptable. Typical stress-strain curves for acrylic fiber in air and in wet conditions are shown in Figure 3. 

Figure 15.17. Typical stress-strain curves of some synthetic polymer, natural polymer, and inorganic fibers. Data obtained at 20°C and 65% relative humidity. Acrylic fibers are made from copolymers composed of at least 85% by acrylonitrile units, -CHj-CH(CN)-.

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