Twaron Aramid

Twaron SRM uses silicone carbide particles as a protective coating deposited onto a special matrix composition that coats the Twaron aramid fabric substrate (Fig. 7.16). The major function of the carbide particles is to dull the blades and make the blade... 

Sheu G S and Shvu S S (1994) Surface modification of Kevlar 149 fibers by gas plasma treatment. Part II Improved interfacial adhesion to epoxy resin, J Adhes Sci Technol 8 1027-1042. de Lange P J, Akker P G, Maeder E, Gao S L, Prasithphol W and Young R J (2007) Controlled interfacial adhesion of Twaron aramid fibers in composites by the finish formulation. Compos Sci Technol 67 2027-2035. 

Conventional air gap wet spinning of the as-polymerized solutions of polymers with Mw 60,000-150,000 (Twaron aramid calibration SEC in methane sulfonic acid) at 180°C into a water or dilute phosphoric acid bath, proceeded readily spindraw ratios attainable depend on spinning orifice diameter and the result normally delivers filaments with a diameter of about 10 mm, which are further washed to a low phosphorus content and drawn (by a few percent at most) at high temperature (>400°C) to produce the final, high modulus product. It is unclear whether the crystal solvate can form... 

A well-known example of a lyotropic LCP is the aramide fibre (Twaron or Kevlar), an aromatic polyamide with the structure ... 

Poly-aramides (ARAMIDS) PPTA nh 0 nh ° 0 ° f Kevlar Twaron ... 

Kevlar (Du Pont) and Twaron (Enka/Akzo) are trade names for the all para aramid, poly(p-phenylene terephthalamide), produced by these companies (Eq. 21.18). 

Fig. 3.5 Structural hierarchy in liquid-crystalline fibers. The mechanical performance of highly oriented polymers can approach the ultimate theoretical properties at high degrees of elongation. Anisotropic, rod-like macromolecules, like aromatic copolyesters composed of 2,6-naphthyl and 1,4 phenyl units, often form oriented structures, which can exhibit liquid crystallinity. Extensive structural studies of fibers of these oriented copolyesters showed a hierarchical structure like the one depicted in this Figure. In aramids (Kevlar or Twaron) similar structures may exist. Adopted with permission from [17]...

Fibrillated aramid (Kevlar and Twaron ) pulps are widely used as a moderately heat-resistant reinforcement in friction formulations. Aramid pulps provide briquettability for preforms, improve friction and wear characteristics, help modify compressibility, and aid in noise damping. However, these flbers are one of the most expensive raw materials used in friction materials. 

Aerospace composite structures can also employ high-performance polymeric fibres such as the aramids Kevlar (DuPont) or Twaron (Teijin Twaron), poly(p-phenyl-ene-2,6-benzobisoxazole) (PBO) (Toyobo) and high-modulus polyethylene (PE) (Dynema, Certran and Spectra). Generally ultra-high-molecular-weight PE (UHMWPE) can be considered to be inert to most environments except that the service temperature is limited to <130 °C. 

C. K. Bottger, R. Harteit, K. R. Stolze, J. Jager, H. van de Ven, and P. G. Akker. Method for producing a hydrophobically finished aramid fabric and use thereof. US Patent 7132131, assigned to Teijin Twaron GmbH (Wuppertal, DE), November 7, 2006. 

H. Werlich, W. ZwUling, and U. Wecker. Process for preparing p-aramide paper, p-aramide pulp, and the use of the paper and the pulp. EP Patent 1277 880, assigned to Teijin Twaron Gmbh (DE), January 22, 2003. 

The situation is very similar on the para side of chemistry. The first and the largest producer—DuPont—has three facilities throughout the world. The largest one in the United States produces essentially all product forms except films. Fiber is also produced in Ireland and Japan. The other producer of p-aramids is Teijin Co., which produces two basic fibers Twaron based on PPTA and Technora based on a copolymer. Twaron is produced in the Netherlands while Technora is manufactured in Japan. 

Source From DuPont Technical Guide for Kevlar Aramid Fiber, H-77848, 4/00 DuPont Technical Guide for Nomex Brand Aramid Fiber, H-52720, 7/01 Teijin Ltd., Teijinconex Heat Resistant Aramids Fiber 02.05 Teijin Ltd., High Tenacity Aramids Fibre Technora TIE-05/87.5 Akzo Nobel, Twaron—Product Information Yarns, Fibers and Pulp. 

Glass and carbon/graphite fibres do not absorb significant quantities of moisture, although glass fibres are eventually attacked, the rate of attack being signihcant with hot water. Aramid fibres (e.g. Kevlar, Nomex, Twaron) in contrast are polymers, just like the matrix resins and therefore they absorb water. The amount is typically about 5% w/w. The fibre/matrix interface is weak, even in the dry condition. 

Primitive reinforced plastics products were known in the 1920s and 1930s, but the more advanced fibre reinforced materials we know today only became significant commercially as structural materials in the 1950s, and even then, the more recent reinforcing fibres such as carbon/graphite, aramid (e.g. Kevlar , Twaron ) and polyethylene (e.g. Dyneema ) fibres were all still completely unknown. The great majority of reinforced plastics articles we use today have been manufactured since 1975. 

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