High-tenacity fiber

Chemically Resistant Fibers. Fibers with exceUent chemical resistance to corrosive and/or chemical warfare agents or extreme pH conditions (eg, very acidic or very alkaline) were initially used for protective clothing. However, appHcations for filtration of gases and Hquids in numerous industrial faciHties are now the more important. For example, PPS is suitable for use in filter fabrics for coal-fired boilers because of its outstanding chemical and heat resistance to acidic flue gases and its exceUent durabUity under these end use conditions. Many high tenacity fibers are also chemically inert or relatively unaffected under a variety of conditions. Aramids, gel spun polyethylene, polypropylene, fluorocarbon, and carbon fibers meet these criteria and have been used or are being considered for appHcations where chemical resistance is important. 

Fig. 20. Stress(er)-strain (ai) dependence for high density polyethylene samples. 1 reference sample, 2 sample obtained if molecular orientation exists, 3 super high tenacity fiber-fibril. Asterisks denote the points of fiber failure...

Analogously, for polyethyleneterephtalate, drawing procedures in multiple steps, with preliminary drawings at room temperature generating a mesomorphic form [127], have been suggested by several authors [128-130], in order to get high modulus and high tenacity fibers. 

High tenacity fibers High test molasses High touch fibers High voltage cables... 

TP polyester offers a low density, high tenacity fiber with good impact resistance but low modulus. It is used in areas where high stiffness is not required, but where low cost, lightweight, and high impact or... 

High-tenacity fibers have been demonstrated by dry-jet wet-spinning of anisotropic solutions of cellulose triacetate, but a product has not yet been commercialized [113,114], Nanofiber composites have been demonstrated by electro-spinning dilute cellulose acetate and triacetate solutions. These composites have exceptionally high specific surface area, and exciting new applications are envisioned [115], There are many new specialty applications, and research is continually finding new applications that take advantage of the unique balance of properties of cellulose acetate [107,109,110,116],... 

Polyamide fibers with much higher softening points than nylon 66 or nylon 6 were produced by a team of DuPont chemists who used aromatic reactants instead of the aliphatic reactants used to produce nylon 66. The aramids which were the first liquid crystal polymers, were spun to produce high tenacity fibers which were sold under the trade names of Kevlar and Nomex. 

The as-spun fibers produced from the polymer with a high melt viscosity of MFI = 12 g/10 nun show a highly oriented a-monoclinic structure. As indicated by the X-ray diffraction patterns and equatorial traces, these fibers are more oriented than the fibers produced with MFI = 35 g/10 min. In fact, the subsequent drawing of the fiber produced from the polymer with low melt viscosity leads to high-tenacity fibers. The overall molecular orientation of as-spun fibers from polymer with high melt viscosity is found to be higher than the fibers produced from... 

Maret et al., 1981). Besides the scientific interest in all of these findings their practical relevance should also be stressed in that they may lead the route to the preparation of high modulus, high tenacity fibers. 

After spinning, the filaments need to be drawn so as to achieve a regular orientation of the chain molecules. The drawing procedure improves the fiber properties such as tenacity and abrasion resistance. The total draw ratio is about 20% for standard fibers and up to 150% for high-tenacity fibers. 

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