Aramid definition

Modem three layers pressure vessels are under study, which consist of a stressbearing component - an inner polymer liner over-wrapped with a carbon-fibre composite - and an outer aramid-material layer, mechanical and corrosion damage resistant [1]. A system for the gaseous hydrogen storage at room temperature has also been designed, adopting a definite number of linked cylindrical pressure vessels [13]. 

Also, fibers are controversial. In one currently used handbook, natural, inorganic fibers such as wollastonite or asbestos have been included among fillers whereas other fibers were included in a separate group with only three materials glass, aramid, and graphite. But, mixtures of fibrous and particulate materials are found in many composites today and various natural materials having fibrous structures are considered fillers in technical papers. Again our definition includes these examples. 

Aramide fibers, according to a definition issued by the US Federal Trade Commission, consist of long-chained synthetic polyamides in which at least 85 % of the amide groups are bound directly to two aromatic rings. DIN specifies that such aramides can also contain imide groups. The worldwide production volume of aramide fibers is 40,000 t/a. 

Conductive fibers are a cross between the world of electric wires and the world of textiles, with attributes of each. Conductive fibers consist of a nonconductive or less conductive substrate, which is then either coated or embedded with electrically conductive elements. Substrate fibers typically include cotton, polyester, nylon, and stainless steel to high-performance fibers such as aramids, HOPE, PBl, PBO, PTFE, carbon nanotubes, and so on. Straddling the worlds of textiles and wires, conductive fibers are sold either by weight or length and measured in denier and AWG. Nanowires are often included in the definition of conductive fibers either because nanotechnology is used by some conductive fiber producers or because the nanowires constitute an electrical conduction means, which does not fit the conventional definition of a wire. 

The superior properties of aramid materials were the reason why significant research effort has been devoted to their synthesis. In 1989 there were at least 100 different chemical compositions of aromatic and aromatic-aliphatic polyamides [5] and there are indications that the number has doubled until today. This fact led the U.S. Federal TVade Commission to adopt a definition for aramid designating fibers of the aromatic polyamide type in which at least 85% of the amide linkages are attached directly to two aromatic rings. The compounds corresponding to this definition that have reached commercial stage are only four (Scheme 8.1) poly(r vphenylene isophthalamide) (MPDI), poly(p-phenylene terephthalamide) (PPTA), copoly(p-phenylene-3,4-diphenyl ether terephthalamide) (ODA-PPTA), and poly[5-amino-2(p-aminophenyl) benzimidazole terephthalamide] (SVM).The process of commercialization of every compound has always been the result of a constant trade-off between properties, processability and price. 

Aramid is the name given to a class of polymers that are aromatic polyamides. The definition of an aramid fiber is a manufactured fiber in which the fiber forming substance is along chain synthetic polyamide in which at least 85% of the amide linkages are attached directly to two aromatic rings . There are various aramid fibers, including poly-m-phenylene isophthalamide known for its flame resistant characteristics (Dupont Nomex ). A second aramid is poly-p-phenylene terephthalamide developed by Akzo and DuPont, which consists of oriented para-substituted aromatic units. This makes polymer chains rigid and rodlike. 

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