High-strength fibres

Amorphous stereotactic polymers can crystallise, in which condition neighbouring chains are parallel. Because of the unavoidable chain entanglement in the amorphous state, only modest alignment of amorphous polymer chains is usually feasible, and moreover complete crystallisation is impossible under most circumstances, and thus many polymers are semi-crystalline. It is this feature, semicrystallinity, which distinguished polymers most sharply from other kinds of materials. Crystallisation can be from solution or from the melt, to form spherulites, or alternatively (as in a rubber or in high-strength fibres) it can be induced by mechanical means. This last is another crucial difference between polymers and other materials. Unit cells in crystals are much smaller than polymer chain lengths, which leads to a unique structural feature which is further discussed below. 

Bastiaansen, C.W.M. (1997) High-modulus and high-strength fibres based on flexible macromolecules, in Processing of Polymers, ed. Meijer, H.E.H. Materials Science and Technology, A Comprehensive Treatment, vol. 18, eds. Cahn, R.W., Haasen, P. and Kramer, E.J. (VCH, Weinheim) p. 551. 

Recently, microscopic-level research has developed very small carbon networks called nanotubes. As you can see in Figure 4.19D, nanotubes are like a fullerene network that has been stretched into a cylinder shape. Nanotubes of C400 and higher may have applications in the manufacture of high-strength fibres. In the year 2000, researchers built a nanotube with a diameter of 4 x 10 m. Up to that time, this nanotube was the smallest structure assembled. 

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

Melamine fibres are primarily known for their inherent thermal resistance and outstanding heat blocking capability in direct flame applications. This high stability is due to the cross-linked nature of the polymer and the low thermal conductivity of melamine resin. The dielectric properties and its cross-sectional shape and distribution make melamine ideal for high temperature filtration applications. It is sometimes blended with aramid or other high strength fibres to increase final fabric strength. 

Ridge, I.M.L., O Hear, N., Verreet, R., Grabandt, O., Das, C. A. (2007) High strength fibre cored steel wire rope for deep hoisting applications. Proceedings of the OIPEEC Conference. Johannesburg OIPEEC. 

T5] high-strength fibre made from carbon atoms... 

Synthesis of aromatic polyesters using bromo, chloro, methyl and methoxy substituted hydroquinones have been reported, to lower the melting temperatures relative to the unsubstituted polyesters. These polyesters have applications in fabricating thermally stable high strength fibres and moulding resins with unusual properties. 

Yang, H.H., Aromatic High-Strength Fibres, John Wiley and Sons, New York, 1989. 

SEl - Sumitomo Electric Industries, 2010. Super high strength fibre reinforced concrete SUQCEM, Newsletter SEI NEWS , v. 398. 

We take up the discussion following Section 8.2.1 above. In a conventional fibre composite a matrix of moderate stiffness ( 1 GPa) is reinforced with a stiff and strong fibre (of modulus 100 GPa). Most usually this is glass or carbon fibre, but high-strength fibres such as aramid or polyethylene fibres are also used. 

J Kretschmer, High strength fibre composite components in the automotive industry (1990, pl77). 

Fig. 9.13. The basal planes of graphite are arranged in parallel to the fibre axis in carbon fibres. In high-strength fibres, the different regions are connected, rendering slip of the planes past each other more difficult (after [29,97])...

Preferred orientation in polymers (see Sect. 1.6.1) can deliver enhanced mechanical properties, especially when the level of preferred orientation is high. Most familiar to many is the case of nylon rope. Polyethylene is another material where very high strength fibres have been used to make ropes and bullet-proof vests. Two kinds of these are commercially available, namely Dyneema from DSM and Spectra from Honeywell. 

Commercially available PAN based carbon fibres with final heat treatment temperatures of 1400 OC are so-called type II or high strength fibres and those with heat treatment temperatures of 2700 oc are type I or high modulus fibres (compare fig. 14 and table 3). 

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