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Fibre reinforcements
Published in A.R. Bunsell, S. Joannès, A. Thionnet, Fundamentals of Fibre Reinforced Composite Materials, 2021
R. Bunsell, S. Joannes, A. Thionnet
Fibres with an enhanced cyclic molecular structure based on polyester chemistry are less well known than the aromatic polyamides but show potential for some composite applications (Pegoretti and Traina, 2018). Polyethylene naphthalate contains two aromatic rings which however are not collinear. The result is fibres with moduli about double that of PET. They can be used as reinforcement for rubber and other plastic materials. They are however more expensive to produce which has limited their use. A liquid crystal aromatic polyester which can be melt spun is produced by Kuraray in Japan as a high-performance fibre called Vectran™. It has a specific gravity of 1.4; a tensile modulus of 103GPa; strength of 3GPa; melting point around 300°C and high thermal stability with a degradation temperature of the polymer above 400°C.
Materials
Published in Ever J. Barbero, Introduction to Composite Materials Design, 2017
The aforementioned advantages and disadvantages of aramid fibers are shared by all polymeric fibers. PBO based fibers are represented by Zylon™ [100] produced by Toyobo, which feature higher strength and stiffness than aramid and excellent tenacity. Polyethylene fibers, the most known being Spectra™ [101] produced by Honeywell International Inc., have lower moisture absorption, lower density, and stiffness-strength properties comparable to aramid fibers, but they also have lower maximum operating temperature (about 120∘ $ 120^{\circ } $ C). They are attractive for construction of radomes because they are highly transparent to electromagnetic waves. Potential applications for structural components are limited because of their low maximum operating temperature. Polyester polymeric fibers such as Vectran™ [102], produced by Kuraray Co., have outstanding properties as shown in Tables 2.3–2.4but they lose about 50% of their strength at about 150∘ $ 150^{\circ } $ C.
Soft body armour
Published in Textile Progress, 2019
Unsanhame Mawkhlieng, Abhijit Majumdar
The tensile strength and modulus of Vectran™ are at par with those of aramids. It has a tensile strength of 24–27 gpd (around 3–3.4 GPa) and a modulus of 600–838 gpd (74–104 GPa). Because of its molecular structure, Vectran™ does not lose its mechanical properties at low temperature or when wet, the latter being attributed to the inherently low moisture absorption tendency of the fibre. With a moisture regain less than 0.1%, its affinity to moisture is lower than that of aramids (3.5% for high modulus, 7% for high tenacity aramids). Its high decomposition temperature in the range of 400 °C enables it to withstand high temperatures and heat. Owing to its excellent tensile properties, Vectran™ may be an alternative choice of material for ballistic applications although its utilization for such applications is not as extensive as aramids and UHMWPEs. Besides, it is another fibre that can compensate for the shortcomings of carbon fibres in fibre-reinforced plastics (FRP) [19].