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Kevlar (para-aramid) [2] is a strong, heat-resistant synthetic fiber, related to other aramids such as Nomex and Technora.Developed by Stephanie Kwolek at DuPont in 1965, [3] [2] [4] the high-strength material was first used commercially in the early 1970s as a replacement for steel in racing tires.
The ultimate tensile strength of a material is an intensive property; therefore its value does not depend on the size of the test specimen.However, depending on the material, it may be dependent on other factors, such as the preparation of the specimen, the presence or otherwise of surface defects, and the temperature of the test environment and material.
The kenaf fibre needs to be treated properly to remove the lignin. The tensile strength of the kenaf fibre is about 800 MPa, which makes it a suitable natural fibre in engineering applications. [8] The core is about 60% of the plant and has fibre cells that are thick (≈38 μm) but short (0.5 mm) and thin-walled (3 μm). [9]
The conductive fiber is used for electronic textiles, EMI shielding in woven or knit sheets, or as a braid over wires, and for signal transmission or current conduction. This conductive fiber combines the advantages of Zylon (strength, resistance to high temperatures, durability, lightweight, etc.) with the electrical properties of various metals.
Cellulose fiber response to mechanical stresses change depending on fiber type and chemical structure present. Information about main mechanical properties are shown in the chart below and can be compared to properties of commonly used fibers such glass fiber , aramid fiber , and carbon fiber .
Compared to wood pulp, hemp pulp offers a four to five times longer fiber, a significantly lower lignin fraction as well as a higher tear resistance and tensile strength. However, production costs are about four times higher than for paper from wood, [ 71 ] since the infrastructure for using hemp is underdeveloped.
It is also known as the strength-to-weight ratio or strength/weight ratio or strength-to-mass ratio. In fiber or textile applications, tenacity is the usual measure of specific strength. The SI unit for specific strength is Pa ⋅ m 3 / kg , or N ⋅m/kg, which is dimensionally equivalent to m 2 /s 2 , though the latter form is rarely used.
Additional advantages of Vectran fiber has a 0.02% creep at 30% of max load after 10 000 hours, high chemical and abrasion resistance and high tensile strength. The UV endurance is inferior to PET and PEN, but the degradation levels off after roughly 400 hours of exposure, while the Aramids and Spectra continue to degrade.