The effect of characteristic self-generated defects on the mechanical behavior of poly(ethylene terephthalate) fibers and films

• Published in: Polymer (Guilford) Vol. 176; pp. 11 - 19
• Main Authors: Kechekyan, Petr A., Arzhakova, Olga V., Kechekyan, Alexander S., Dolgova, Alla A., Volynskii, Aleksandr L.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 02-08-2019; Elsevier BV
• Subjects: Characteristic defects; Compression; Crazes; Defects; Delayed necking; Edge dislocations; Ethylene; Fibers; Interfaces; Mechanical properties; Polyethylene terephthalate; Shear bands; Strain; Stress-strain curves; Stress-strain relationships; Yield point; Yield stress; Characteristic defects; Delayed necking; Stress-strain curves; Shear bands; Crazes
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2019.04.022

This paper addresses specific structural and mechanical behavior of poly(ethylene terephthalate) (PET) fibers and films with characteristic self-generated characteristic defects. Characteristic defects with multiple interfaces (as crazes and/or shear bands) are self-initiated in the PET fibers and films due to their benign pre-loading (loading below yield stress, uniaxial compression, etc.). Mechanical behavior of the PET samples with characteristic defects is characterized by unusual stress-strain curves, which are appreciably different from that of the pristine PET sample. The yield point and the sharp stress drop corresponding to the onset of necking appear to be markedly spaced along the strain axis by appreciable strains (even up to ∼40%). This unusual behavior of the PET fibers and films with characteristic defects is referred to as the phenomenon of delayed necking and the conditions providing this phenomenon are outlined.
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•The behavior of glassy polymers with characteristic defects is studied.•Characteristic defects are shear bands and crazes with multiple interfaces.•Different methods for nucleation of characteristic defects are used.•The phenomenon of “delayed necking” is observed for the first time.•The mechanism of this phenomenon is advanced.