Heat setting

Abstract

As-manufactured polymeric fibers are oriented semi-crystalline structures in which the macromolecules are rarely in their equilibrium state. Further instabilities are imparted when the fibers are converted to yarns and the yarns to fabrics. Heat setting is an important industrial process, since it rids them of their instabilities. This review article first considers aspects that are relevant to the broad area of heat setting, viz., the origin of instability, the durability of set, thermal and dynamic mechanical transitions, thermodynamic basis of setting, shrinkage and shrinkage stress, and characterization of the degree of set. The heat setting of major thermoplastic fibers, viz., polyester, polyamide, polyacrylonitrile, polypropylene, and polyethylene has been described in terms of the conditions of heat setting, the structural and morphological changes that occur on heat setting, and the changes in their physical properties. It is shown that heat setting affects such important properties as stress-strain and recovery behavior, dye-uptake, optical properties, and thermal properties. The structural and morphological changes have been described in terms of changes in crystallinity, crystal size and their size distribution, crystal defects, crystal orientation, the nature of the amorphous phase and its orientation, the coupling of the crystalline and amorphous phases, etc. The structural basis of property changes is then discussed.

Viscoelastically generated prestress from ultra-high molecular weight polyethylene fibres

“…For UHMWPE fibres, there is less certainty. Gupta [12] suggests that any meaningful heat-setting (to remove structural instabilities) of highdensity polyethylene fibres would be performed at *120°C; however, it may be inferred from Ref. [12] that the need to anneal UHMWPE fibres is more questionable, due to their high crystallinity.…”

“…Gupta [12] suggests that any meaningful heat-setting (to remove structural instabilities) of highdensity polyethylene fibres would be performed at *120°C; however, it may be inferred from Ref. [12] that the need to anneal UHMWPE fibres is more questionable, due to their high crystallinity. Thermal treatment (0.25 h) of UHMWPE fibres shows that tensile strength is unaffected, though modulus decreases and strain-to-break increases progressively with increasing temperature up to 130°C [13].…”

The Influence of Annealing Process on Crystallinity and Structural Properties of Cotton/Spandex Fabric

“…Heat setting, in every one of these operation, sometimes, accomplishes the basic objective in swelling agents and tension manifestation, specifically in taking the product toward equilibrium in order to see to it that resistance is attained against thermal shrinkage and dimensional changes, as well as in curling and creasing. It is possible for improvements to be attained in physical properties, specifically in mechanical properties [5]. In their work with polyester fibres [6,7], Gupta and Kumar made a comparison of slack and taut heat set yarns with regards to a non-heat set sample based in changes in their structures and mechanical properties.…”

Effects of Time of Heat Setting and Wet Processes on Tensile properties of Griege Knitted Ingeo™ Poly Lactic Acid (PLA) Fabric

“…of appropriate softening agents. The application of softeners produces a level of softness which may not be attained by mechanical finishing or modification of fabric construction [22].…”

“…Heatsetting of fibers introduces enhanced dimensional stability to the fiber thereby improving fiber morphology and orientation. Heatsetting temperature should be higher than the maximum temperature of the subsequent wet processes such as dyeing and ironing temperature so as to ensure the fabric attains dimensional stability [22][23].…”