Polyacrylonitrile filaments

Diazoazoles, pyrazoles, and imidazoles also found applications in the photographic processes as precursors of triazenes, which are useful as additives for developers in color photography (73GEP2253615). In the texile industry, azo dyes obtained from diazopyrazoles showed dyeing properties on cotton, wool, and nylon 6 (47USP2420791 82MI1). Also, 1,3-ditetrazolyltriazene improved dyability and the feel of polyacrylonitrile filaments (58BRP796294). 

Process. Any standard precursor material can be used, but the preferred material is wet spun Courtaulds special acrylic fiber (SAF), oxidized by RK Carbon Fibers Co. to form 6K Panox B oxidized polyacrylonitrile (PAN) fiber (OPF). This OPF is treated ia a nitrogen atmosphere at 450—750°C, preferably 525—595°C, to give fibers having between 69—70% C, 19% N density less than 2.5 g/mL and a specific resistivity under 10 ° ohm-cm. If crimp is desired, the fibers are first knit iato a sock before heat treating and then de-knit. Controlled carbonization of precursor filaments results ia a linear Dow fiber (LDF), whereas controlled carbonization of knit precursor fibers results ia a curly carbonaceous fiber (EDF). At higher carbonizing temperatures of 1000—1400°C the fibers become electrically conductive (22). 

P.R.176 provides very lightfast polyacrylonitrile spin dyeing products. The samples equal step 6-7 on the Blue Scale. Dry and wet crocking may affect the objects to a certain extent. P.R.176 is also used in polypropylene spin dyeing, especially for coarse textiles, such as carpet fibers, split fibers, filaments, bristles, or tape, but also for finer denier yams. A special pigment preparation for this purpose is commercially available. 1/3 SD samples tolerate exposure to up to 300°C for one minute or up to 290°C for 5 minutes. In terms of lightfastness, 0.1% colorations equal step 5-6 on the Blue Scale, while 2% samples match step 7. 

Carbon fibers have been used as filaments for lamps for nearly a century, since Edison first used them. In the early 1960s, Shindo developed the first modern carbon fiber when he pyrolyzed polyacrylonitrile (PAN) fibers [5]. 

The first continuous filaments were rayon, and these, as well as polyacrylonitrile (PAN) fibers, have been pyrolyzed to produce graphite fibers. High-modulus reinforcing filaments have also been produced by the deposition of boron atoms from boron trichloride vapors onto tungsten or graphite filaments. 

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. 

The first high-strength carbon fibres were produced in the 1950s (see Donnet and Bansal, 1984). The early carbonized products were rayon-based, but it was soon found that the mechanical properties and the carbon yield could be improved by the use of polyacrylonitrile (PAN) as the precursor. Also, less expensive fibres of somewhat lower strength and modulus could be made from various other precursors including petroleum pitch and lignin. However, cotton and other forms of natural cellulose fibres possess discontinuous filaments and the resulting mechanical properties were consequently found to be inferior to those of the rayon-based fibres. 

The intrazeolitic polymerization of acetylenes and of several heteroaromatics, including pyrrole, thiophene, and aniline, has been explored to the greatest extent. Furthermore, intrazeolite carbon filaments based on the pyrolysis of intrazeolite polyacrylonitrile have been prepared, and some of the reported structures show significant electronic conductivity. Based on this knowledge, encapsulation of additional polymers and other conducting structures in this family of hosts is anticipated. 

These fibers, obtained by pyrolysis of polyacrylonitrile, have a tensile strength of 2.41 GPa and tensile modulus of 391 GPa. Tows containing several thousand THORNEL 50 filaments were woven into three dimensional, orthogonal preforms in one of two manners, illustrated in Figure 1. Weave 2 (W2) was relatively coarser than weave 1 (Wl), although fiber volume in the preforms was similar (30.0% for W1 and 31.2% for W2). 

ST staple F filament yarn PA polyamide PAN polyacrylonitrile PVC polyvinyl chloride PU polyurethane. Source From Chinese Chemical Fiber Association, Fiber Organon, 2003, 6. 

Man-made fibres.ThesQdo Qtiihexsynthetic (nylon, poly(ethylene terephthalate), polyacrylonitrile, polypropylene, aramide, etc.) or cellulosics (viscose, cellulose acetate). They are available in the form of continuous yarns (filament, filament yarn) or staple fibres. Inorganic fibres as glass and carbon are also man-made fibres. 

Carbon fibers were first made by Thomas Alva Edison in 1879 from cellulose for lamp filaments. In Great Britain in 1961 the Royal Air Force produced a high-value carbon fiber from polyacrylonitrile (PAN). 

The existence of carbon liber (CFs) came into being in 1879 when Thomas Edison recorded the use of carbon fiber as a filament element in electric lamp. Fibers were first prepared from rayon fibers by the US Union Carbide Corporation and the US Air Force Materials Laboratory in 1959 [41 ]. In 1960, it was realized that carbon fiber is very usefirl as reinforcement material in many applications. Since then a great deal of improvement has been made in the process and product through research work carried out in USA, Japan and UK. In 1960s, High strength Polyacrylonitrile (PAN) based carbon fiber was first produced in Japan and UK and pitch based carbon fiber in Japan and USA. 

This study demonstrates the inclusion synthesis of polyacrylonitrile in the channel systems of NaY and Na-mordenite zeolites, and its pyrolysis to yield a conducting material consisting of nanometer size carbon filaments. These and related systems are promising candidates for low-field conductivity at nanometer scale (timensions. 

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