Stress-Strain Behavior of Commercial Fibers

Although un-oriented amorphous and semicrystalline polymer fibers are important and they often are the intermediate products of moleculariy oriented fibers, most commercial polymer fibers ate moleculariy oriented, except for a few elastomeric polymer fibers. The molecular orientation in natural polymer fibers occurs by itself under the control of genetic codes. For synthetic polymer fibers, molecular orientation is introduced purposely by high-speed spinning or drawing to enhance the mechanical properties of these fibers so they can be converted into useful final products. 

Based on the stress-strain behavior, moleculariy oriented polymer fibers can be divided into three groups high modulus-high tenacity (HM-HT) fibers, tough 

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