High tenacity fibre

Polyacrylonitrile synthesized by radiation emulsion polymerization is used for manufacturing high tenacity fibres. 

Expansion of the hybridization between metals and eomposites has led to a re-examination of the role of metals in helmet systems. As expressed earlier, metals (namely steel) had been the armour material of ehoiee before the development of high-tenacity fibres. Since then, steel has been discarded from helmet material selection. While some have explored the rrse of alirminiirm, magnesium and titanium shells, the general performance gains were not substantial enough to justify the subsequent processing and interfacing, whilst concerns were also raised about their durability (Walsh et ai, 2008). 

The optical properties of interest are refractive index and molecular refraction, polarisation, double refraction (birefringence) of isotropic and oriented PE, clarity, transparency, haze, and gloss (see Tables 3.1 and 3.9). PE granules are white and translucent, but the final appearance varies from hard, rigid, brightly coloured, glossy, flexible or transparent film to high-tenacity fibre. In the melt state the refractive index is 1.4297 and 1.4432 and the molar refractivity is 0.3297 and 0.32986 for HDPE and LDPE, respectively. 

The overall properties of the composites are dependent on the matrix properties, the fibre content (Figure 10.8), its modulus of elasticity, and the various means used to improve the fibre-matrix bond. A variety of different fibre types have been studied, including monofilaments of various diameters, fibres with buttons on their ends [21], twisted tapes [21], fibrillated mats [26], textile fabrics [18] and high tenacity fibres with frayed ends [7], Even with smooth monofilament... 

Hence, the main aim of the technological process in obtaining fibres from flexible-chain polymers is to extend flexible-chain molecules and to fix their oriented state by subsequent crystallization. The filaments obtained by this method exhibit a fibrillar structure and high tenacity, because the structure of the filament is similar to that of fibres prepared from rigid-chain polymers (for a detailed thermodynamic treatment of orientation processes in polymer solutions and the thermokinetic analysis of jet-fibre transition in longitudinal solution flow see monograph3. ... 

ISO 1346 2004 Fibre ropes - Polypropylene split film, monofilament and multifilament (PP2) and polypropylene high tenacity multifilament (PP3) - 3-, 4- and 8-strand ropes ISO 1873-1 1995 Plastics - Polypropylene (PP) moulding and extrusion materials - Part 1 Designation system and basis for specifications ISO 1873-2 1997 Plastics - Polypropylene (PP) moulding and extrusion materials - Part 2 Preparation of test specimens and determination of properties ISO 3213 1996 Polypropylene (PP) pipes - Effect of time and temperature on expected strength... 

PAN carbon fibres High tenacity High modulus Improved tenacity High modulus... 

Recently elastic polyolefin fibres have also been introduced (generic name lastol), they are cross-linked and stable at temperatures up to 220 °C and above.- High-tenacity polyethylene fibres, with ultra high molecular weight (UHMW-PE, Dyneema) have been available for some time they are produced by a gel-spinning process at high dilution. 

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. 

Teijin Ltd., High Tenacity Aramids Fibre Technora TIE-05/87.5. 

There are a range of fibre types available, which cover a broad spectrum of material stiffness and strength. The most widely used and inexpensive carbon fibres (Table 15.3) are high tenacity (HT) fibres. A good... 

Most technical yams for reinforcement are based on continuous multifilament yams having linear densities typically in the 1100 dtex (1000 denier) region in singles or doubled configurations. The number of filaments per yam will vary between about 140 and 200 for melt-spun nylon 6.6 and polyester to >500 for high tenacity viscose and other wet-spun fibres, including the aramids. For instance, Kevlar 29, suitable for rubber reinforcement, is available as a 1670 dtex yam with 1000 filaments. "... 

Table 11.5 High tenacity, manufactured fibre, tensile properties... 

Ganster J, Pinnow M, Fink H-P (2006) High tenacity man-made cellulose fibre reinforced thermoplastics - injection moulding compounds with polypropylene and alternative matrices. Compos A 37 1796-1804... 

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