Ultra high strength

Because of their unique blend of properties, composites reinforced with high performance carbon fibers find use in many structural applications. However, it is possible to produce carbon fibers with very different properties, depending on the precursor used and processing conditions employed. Commercially, continuous high performance carbon fibers currently are formed from two precursor fibers, polyacrylonitrile (PAN) and mesophase pitch. The PAN-based carbon fiber dominates the ultra-high strength, high temperature fiber market (and represents about 90% of the total carbon fiber production), while the mesophase pitch fibers can achieve stiffnesses and thermal conductivities unsurpassed by any other continuous fiber. This chapter compares the processes, structures, and properties of these two classes of fibers. 

Holms, S. and Schwartz, P. (1990). Amination of ultra-high strength polyethylene using ammonia plasma. Composites Sci. Technol. 38, 121. 

Li, Z.F., Netravali, A.N. and Sachse. W. (1992). Ammonia plasma Ireatmeni of ultra-high strength polyethylene fibers for improved adhesion to epoxy resin. J. Mater. Sci. 27, 4625-4632. 

Metal containing polymers have emerged as a new generation material with tremendous potential in fields like superconducting materials, ultra-high strength materials, liquid ciystals and biocompatible polymers. 

Similar reactions to those used in interfacial polymerizations are sometimes carried out in solution and are employed to prepare some polymers which yield ultra-high-strength high modulus fibers. Tliese species typically contain para-linked aromatic rings and amide or ester linkages in the polymer backbone. 

Table 1 Some commercially available ultra high strength fibres and their properties.

Ingot iron Wrought iron Gray cast iron Carbon steels, SAE 1020 Ultra-high-strength steel, 300-M... 

Ultra high-strength hydraulic cement compositions... 

Wei, R. P., Talda, P. M., and Li, C.-Y., Fatigue-Crack Propagation in Some Ultra-High-Strength Steels, ASTM STP 415 (1967), 460. 

Some three decades ago, scientists from the Du Pont company developed polycondensation methods which allowed the preparation of high molecular weight wholly aromatic polyamides. The first commercially produced wholly aromatic polyamide fibre was poly(m-phenyleneisophthalamide) (Nomex, Du Pont, 1967) [la, c]. Some years later, development of the preparation and processing of poly(p-phenyleneterephthalamide) (PPTA) led to the commercialization of the para product Kevlar (Du Pont) in the early seventies [lb, c]. While Nomex shows excellent thermal stability and flame-retardance, and indeed is referred to as a heat and flame resistant aramid fibre, Kevlar fibre also has similar properties, but in addition it has exceptional tensile strength and modulus, and is referred to as an ultra-high strength, high modulus aramid fibre. 

W. Peterson, Diluhon of Weld Metal to Ehnhnate Interfacial Fractures of Spot Welds in High and Ultra-High Strength Steels, Proc. Int. Conf. Advances in Welding Technology (Columbus, OH), EWI/AWS/NJC/SME/TWI, Sept 17-19, 1997, p 331-346... 

Liquid crystalline polymers are important in the fabrication of lightweight, ultra-high-strength, and temperature-resistant fibers and Aims such as Dupont s Kevlar and Monsanto s X-500. The structural factors responsible for promoting the above classes of polymers will be discussed when we treat the structure of polymers. 

The mechanism underlying the formation of the ultra high strength and modulus of UHMW PE by means of the surface growth technique is as follows. 

P. Smith and P.J. Lemstra, Ultra-high strength polyethylene filaments by solution... 

Lohaus, L., Anders, S., 2004. Effects of polymer modification on the mechanical and fracture properties of high and ultra-high strength concrete. In ICPIC 04, 11. International Congress on Polymers in Concrete (2004), p. 183-190, Berlin BAM... 

Z. Feng, B. Ranby, Photoinitiated surface grafting of synthetic fibers. 1. Photoinitiated surface grafting of ultra-high strength polyethylene fibers. Ange-wandte Makromolekulare Chemie 195 (1992) 17. 

Matsusue, Y, Yamamuro, T, Oka, M. et al. (1992) In vitro and in vivo studies on bioabsoibable ultra-high-strength poly(L-lactide) rods Journal Biomaterial Resource, 26, 1553—1567. 

More recently, lyotropic PLCs were catapulted into the forefront of polymer research when ultra-high strength polymer fibers were commercialized by spinning mesomorphic solutions of poly(p-aromatic amides), e.g., Du Pont s Kevlar. I have recently reviewed these aspects of PLCs.(25)... 

Outside of alluding to the importance of PLCs in the fabrication of ultra-high strength organic materials, I have not addressed the applications of PLCs, a major source of the intensive interest in PLCs. The slower time scales for mesophase reorientation will limit the use of PLCs in dynamic electro-optical devices, but the possibility of locking in liquid crystal textures into stable solid polymer films renders PLCs attractive alternatives in static optical devices, e.g., as polarizers, notch filters and non centro-symmetric matrices for non-linear optical phenomena. 

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