Yarn tenacity

Figure 2. Thermal stabilizing activity in 240/30 denier polypropylene yarn (yarn tenacities 5.2 4%).

Figure 8 Average yarn tenacities (cNtex r) at various point across the sail...

FIGURE 4.22 Relationship between fiber (yarn) tenacity and degree of polymerization of PVA fiber. (From Ohmori, A., Sakuragi, I., and Onodera, M., Sen-i Gakkaishi, 55, 418, 1999.)... 

Yarn Tenacity Loss after Exposure to Bleaching Fluid... 

Table 2.3 Relative importance of input parameters for ring yarn tenacity [Source ...

Table 5.4. Prediction of yarn tenacity with Gaussian and triangular membership...

Relationship of Cotton Fiber Properties to Yarn Tenacity... 

Spun yarns always have a certain number of twists that determine the yarn tenacity through fiber-fiber friction. If a yarn is twisted too high, it tends to curl, whereas it can easily break if the twist level is too low. 

Standard Test Methods for Tire Yarns, Cords, and Woven Fabrics. ASTM standard D885M-94 includes test methods for characterizing tire cord twist, break strength, elongation at break, modulus, tenacity, work-to-break, toughness, stiffness, growth, and dip pickup for industrial filament yams made from organic base fibers, cords twisted from such yams, and fabrics woven from these cords that are produced specifically for use in the manufacture of pneumatic tires. These test methods apply to nylon, polyester, rayon, and aramid yams, tire cords, and woven fabrics. 

Data range for regular-high tenacity yarns, ref. 124. Ref. 260. 

Phototendering of PET and PET-co-4,4 -BPDC Filament Yarns. Both "P T homopolymer and PET-co-4,4 -BPDC copolymers were irradiated from 20 to 80 hours in the photolysis chamber. In order to account for the lamp aging, the phototendering rate curves were plotted as percent loss tenacity versus total quanta/cm2 of exposure, rather than irradiation time. The phototendering rate curves for the homopolymer PET and PET-co-4,4 -BPDC copolymers show that all the samples became weaker and showed a decrease in percent elongation to break as total quanta/cm of exposure was increased (Figure 21). 

High tenacity, tire cord yarn viscose 3.7 9.7 27.0... 

Relative scales of the spinning processes for staple and filament products are depicted in Table 12.1. The industrial filament process is intermediate to the staple and textile filament processes, in terms of both spinning throughput and fiber orientation uniformity (here measured by spun birefringence level). Industrial yarns must be uniform enough to be drawn to much higher tenacity levels than staple yams, but are not dyed and therefore not subject to the more demanding uniformity requirements of textile yams. 

As expected, the residual extensibility of the fiber decreases at higher draw ratios. What is not so predictable is that the true stress at failure increases as the draw ratio increases fiber failure strength is improved by drawing the yarn. If a curve is drawn to connect the end points of the stress-strain curves, it is seen that there is an inverse relationship between tenacity and elongation to break (eb). The form of this relationship is as follows ... 

Figure 1. Plot of percent decrease of tenacity vs. percent grafting. Key , rayon yarn O, defatted jute C, bleached jute.

FIG. 13.87 Diagram of the specific tenacity (specific dynamic tensile modulus (Ea/p), for modern high-performance filaments. The diagonal lines have the indicated ratio, which is the theoretical elongation at break (fractional) high-performance yarns have refractory materials have values between 0.025 and 0.005. (ty = tire yarn). 

FIG. 13.88 Diagram of the specific tenacity (ffb/p) versus the initial specific modulus (Ea/p) for conventional man made fibres. 0 is the limiting tangential slope in the stress-strain diagram for strain tending to zero. The diagonal lines show the indicated ffbr/ 0-ratio this varies from = 1 for elastomeric filaments and 0.2 for tyre yarns (ty) to 0.03 for yarns such as polyacrylonitrile. 

Morphology Some polymers, like PETP, are spun in a nearly amorphous state or show a low degree of crystallinity. In other polymers, such as nylon, the undrawn material is already semi-crystalline. In the latter case the impact of extension energy must be sufficient to (partly) "melt" the folded chain blocks (lamellae) in all cases non-oriented material has to be converted into oriented crystalline material. In order to obtain high-tenacity yarns, the draw ratio must be high enough to transform a fraction of the chains in more or less extended state. 

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