Page 347 - Fiber Fracture

Fiber Fracture
M. Elices and J. Llorca (Editon)
0 2002 Published by Elsevier Science Ltd. All rights reserved

FRACTURE OF COMMON TEXTILE FIBRES

J.W.S. Hearle

The Old Wcarage. Melloz Stockport SK6 SIX, UK

Introduction ..................................... 33 1
Cotton and Related Fibres. ............................. 333
Structure and Stress-Strain Curves ...................... 333
Fracture ..................................... 335
Wool and Hair .................................... 337
Structure and Stress-Strain Curve ....................... 337
Fracture. .................................... 339
Melt-Spun Synthetic Fibres ............................. 34 I
Structure and Stress-Strain Curves ...................... 341
Fracture ..................................... 344
Solution-Spun Fibres ................................ 346
Structure and Stress-Strain Curves ...................... 346
Fracture ..................................... 348
Other Modes of Failure ............................... 350
References. ..................................... 352

Abstract

Cotton, polyester, nylon, acrylic, rayon, wool and some other fibres are used in
large quantities by the textile industry for a great variety of uses. Their tensile fracture
results from the total deformation up to the break point. In cotton, a helical assembly of
fibrils, with reversals and convolutions, determines the stress-strain curve. Three forms
of break are found as transverse bonding becomes weaker with moisture absorption.
In wool, extension is controlled by a special microfibril-matrix structure, with fracture
occurring when the rubbery matrix reaches its limiting extension. In melt-spun syn-
thetics, the structure is uncertain, but deformation combines plastic yielding associated
with crystalline regions and rubber elasticity in amorphous tie-molecules. Failure is
due to ductile crack propagation. Solution-spun fibres have a coarse structure that gives
granular fractures. Weakness in the transverse direction leads to axial cracks under shear