Modified acrylic fiber

Recently, nitrilases have been applied to polymer modification, specifically to the modification of polyacrylonitrile (PAN). Nearly 3 x 106 tons of PAN are produced per annum and used in the textile industry. However, there is a great need to improve moisture uptake, dyeability with ionic dyes, and feel of this acrylic fiber. The cyano moieties of PAN have been successfully modified to carboxylates with the commercial Cyanovacta nitrilase, thus enhancing the aforementioned properties of PAN [98]. Nitrilase action on the acrylic fabric was improved... 

Improved Comfort Properties. Wear comfort generally means cotton-like properties, The ability lo absorb moisture from the skin and ihe softness of cotton fabrics are considered to be the two key properties for comfort. The extremely line denier of cotton fibers accounts for its softness. Both properties can be achieved in acrylic fibers. Improved moisture retention can be achieved by incorporating hydrophilic comonomers that decrease ultimate fiher density, by modifying the fiber spinning process, ur by using after-treatments such as modified finishes. 

Acrylic Fibers. Table VII shows that crystallinity of poly acrylonitrile is only slightly modified by heat treatments. The fraction of crystalline material seems rather distorted, as judged by the k values. Wet treatments alone allow substantial amounts of distortions to be removed. Water molecules could enter the ordered regions and relax dipole-dipole interactions, allowing some molecular motion. 

Pure acrylonitrile may polymerize at room temperature to polyacrylonitrile (PAN), a compound that, unlike polyamides and polyesters, does not melt at elevated temperatures but only softens and finally discolors and decomposes. Nor is it soluble in inexpensive low-boiling organic solvents. Because fibers made from it resist the dyeing operations commonly used in the textile industry, the usual practice is to modify it by copolymerization with other monomers, for example, vinyl acetate, styrene, acrylic esters, acrylamide, or vinyl pyridine in amounts up to 15 percent of the total weight (beyond which the final product may not be termed an acrylic fiber). The choice of modifier depends on the characteristics that a given manufacturer considers important in a fiber, the availability and cost of the raw materials in the manufacturer s particular area of production, and the patent situation. 

This product is a modified quaternary type retarding material found to be especially useful in the dyeing of acrylic fibers with cationic and basic dye-stuffs. This product is quite useful in dyeing carpet yarns to give retarding and leveling. 

Aoryiic fibers have a market share of about 20% in the tremendous woddwide production of synthetic fibers, which presently amounts to some 7x10 metric tons par year The acrylic fibers are made from pdymers con >osed of at least 85% by weight of acrylonitrile, modified by one or more other monomers. Elespite the large volume production of acrylic fibers, much of the polymer chemistry and fiber phyrics involved, and particularly of the inter-relations between both, is still far from being fully understood. 

Table 1 shows the specifications of the concrete, carbon fiber sheet and adhesive resin investigated in the present work. The concrete blocks of 30 x 20 x 90 mm were made of normal grade Portland cement and cured in water for 4 weeks. The carbon fiber sheet (UT70-30, Toray) was a unidirectional cloth bound with a few lateral fibers. The adhesive resin (DK-530, Denka) was a modified acrylic resin of two component system. 

Can Bond SPA. [Astro Industries] Modified acrylic polymer slij roofing agent for dl fibers. 

Yoracryl. [Yorkshire Pat-Chem] Cationic basic dyes for acrylic, modified acrylic, and other fibers. 

Acrylonitrile is used in the production of acrylic fibers, resins, and surface coating as an intermediate in the production of pharmaceuticals and dyes as a polymer modifier and as a fumigant. It may occur in fire-effluent gases because of pyroly-ses of polyacrylonitrile materials. Acrylonitrile was found to be released from the acrylonitrile-styrene copolymer and acrylonitrile-styrene-butadiene copolymer bottles when these bottles were filled wifh food-simulating solvents such as water, 4% acetic acid, 20% ethanol, and heptane and stored for 10 days to 5 months (Nakazawa et al. 1984). The release was greater with increasing temperature and was attributable to the residual acrylonitrile monomer in the polymeric materials. 

Bonnets for mini excavators manufactured by Kobe Steel, Japan, are molded by RTM using a modified acrylic resin and glass fiber fabric. The 850 mm wide x 420 mm high component has double curvature and is molded with a glass fiber strand preform with surface mat on the outer surface, preformed with an organic binder. The resin system contains 100... 

Railway carriage interior components molded by RTM have been developed by Kobe Steel Europe with Transintech, UK, and Compin, France. A lightweight (5 kg) seat back shell with high static load and absorption capacity is molded in a modified acrylic resin (from Ashland) with a filler combination to achieve low fire, smoke and toxicity (FST) properties (which is easy to mold by RTM, with little effect on mechanical properties). A combination of glass fiber-based fabrics of 45° non-crimp (936 g/m ) with unidirectional reinforcement and continuous filament mat (450 g/m ) is used. 

Major technical problems were solved by these companies to keep their commercial efforts alive. Difficulties in dyeing were overcome by developing cationic dyes and by modifying the fiber morphology with comonomers, such as methyl acrylate (MA) and vinyl acetate (VA). 

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