Acrylic fibers specialized products

Aqueous systems have been studied by a very large number of investigators. Economy, safety, convenience and quality of product have combined to make this the method of choice for commercial production of copolymers. The industrial importance of such end products as elastomers and acrylic fibers has been a special incentive to related fundamental studies. Furthermore, the relatively high solubility of acrylonitrile monomer in water coupled with insolubility of the polymer make it a convenient test monomer for studies of initiation by redox systems (6, 25, 102). Large numbers of homogeneous chemical initiators and some heterogeneous initiators have been studied as well as initiation by photochemical means, by ultrasonics and by ionizing radiation. It will not be possible here to review the enormous world literature. Several publications (/, 92, 117) refer in some detail to the older papers, and we shall restrict our comments to recent interpretations that have received support from several quarters. 

Acrylonitrile (AN) is one of the leading chemicals with a worldwide production of about 6 million tonnes in 2003. The most important applications are acrylic fibers, thermoplastics (SAN, ABS), technical rubbers, adiponitrile, as well as speciality polymers. Details about technology can be found in the standard textbooks... 

Courtaulds introduced, specifically for the manufacture of carbon fiber, a Special Acrylic Fiber (SAF), which was made at the Coventry works using the same dope, but spun on production lines with additional filtration and individual dope spinning pumps, enabling precise d tex control for smaller tows. Courtaulds ceased production of their Special Acrylic precursor (SAF) in 1991. 

Fibrillated Fibers. Acrylic fibers are sold in the form of fibrillated pulps for use as highly efficient binders. These fibrillated fibers have a tree-like structure with limbs (fibrils) attached to the main trunk (fiber). The trunk is 20-50-fx diameter and the limbs range from a few microns to snbmicron. The product is generated from a special precursor fiber by intense mechanical action. Commercial examples are CCF from Sterling Fibers, Acri-Pulp from Solntia, and Dolanit lOD from Acordis. 

There are many different routes that the starting materials for plastics can take on the way to the user. In this book, we are concerned with those plastics that are supplied to the processor in the form of granules, powder, pellets, flake, or liquids and in turn they are transformed into plastic products. However, the same starting materials used to make these plastics can take other routes and end up in the textile industry (nylon fibers share common roots with a molded nylon gear acrylic fibers share common roots with acrylic sheet for glazing etc.), paint industry, adhesives industry, and other industries meeting their special requirements. 

Thus Courtaulds withdrew from polyester and from Nylon to concentrate on its acrylics and cellulose fibers ICI focused on Nylon and Bayer on acrylics Rhone-Poulenc withdrew from acrylics but revamped its Nylon and polyester units well-integrated in upstream intermediates Montedison decided in favor of polyester and acrylics AKZO focused on polyesters and on aramide fibers while keeping up its profitable rayon sector. Such efforts, which aimed to reduce European chemical fiber capacities by 900,000 tons and to increase productivity through specialization, undoubtedly corrected the situation. 

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