Heat setting is a process used to stabilize manufactured fibers like polyester and nylon. It involves heating the fibers above their glass transition temperature to allow the polymer chains to relax into a new configuration, then cooling to fix them in place. This process reduces shrinkage and distortion. There are different types of heat setting that provide varying levels of dimensional stability. Care must be taken to ensure uniform heating and avoid issues like loss of dye uptake or hand feel. Heat setting improves properties like crease resistance and shape retention in thermoplastic fibers.

1. HEAT SETTING OF
MANUFACTURED FIBRES
• SUBMITTED TO- PROF. MUKESH KR. SINGH
• SUBMITTED BY- ARUN KR. MISHRA

2. INTRODUCTION TO HEAT SETTING
 Heat setting is carried out to bring the material to it’s thermal
equilibrium the material wouldn’t changes it’s morphology
it’s kept at that temperature for a long.
 Heat setting is also known as ANNEALING.
 The degree of set, a term often used to describe the extent
of heat setting is the measure of how close the material has
moved to a thermal equilibrium. A 100% set material is
considered to be at its thermal equilibrium at a given
temperature.

3. Mechanism of Heat Setting
• The setting temperature used is
above Tg. In heat setting, inter-chain
bonds, such as hydrogen and dipole
bonds, break. This allows the
molecular chains to move and adopt
new, stress-free positions. New
intermolecular bonds then form with
the fabric in a relaxed condition at
the setting temperature. After
cooling, the polymer molecules in
the filaments become frozen in
place. The new bonds are stable up
to the heat setting temperature. The
reorganized internal polymer
structure, and the material’s
dimensions, will be stable.

4. Purpose of Heat Setting
 The purpose of heat setting is to dimensionally stabilize fabrics
containing thermoplastic fibers.
 Polyester and nylon are the principal fibers involved. Blended
polyester/cotton fabrics are produced in large quantities. These
fabrics may shrink, or otherwise become distorted either during
wet processing or in the consumer's hands. Heat setting is a way of
reducing or eliminating these undesirable properties.
 The process is relatively simple - pass the fabric through a heating
zone for a time and at a temperature that resets the thermoplastic
fiber's morphology memory.

5. Purpose of Heat Setting
 The new memory relieves the stresses and strains imparted to the fiber by the
yarn - making and weaving processes, and makes stable the configuration it finds
itself in flat smooth fabric.
 This newly imparted memory allows the fiber to resist fabric distorting forces
and provides a way to recover from them.
 The time and temperature needed for the heat treatment depend on fabric
density and previous heat history of the polyester. Time and temperature must
exceed that imparted by previous heat treatments.
 Usually 15 - 90 seconds at temperatures of 385 – 415˚F. will suffice. The heat
setting equipment can be hot air in a tenter frame, or surface contact heat from
hot cans. While the process is simple, careful control is required.

6. WHY HEAT SETTING IS DONE ….?
Heat setting is a heat treatment by which shape retention,
crease resistance & elasticity are imparted to the fibres.
It also brings changes in strength, stretchability, softness,
dyeability & sometimes on the colour of the material.
All these changes are connected with the structural &
chemical modifications occurring in the fibres.

7. TYPES OF HEAT SETTING
Heat setting
Temporary
heat setting
Semi-
permanent
heat setting
Permanent
heat setting

8. TEMPORARYHEAT SETTING-
This type of heat
setting is destroyed by
regular use of material.
For ex:- A steam
pressed cotton textiles.

9. SEMI-PERMANENTHEATSETTING-
In this tye of heat setting
material is raised above
their glass transition
temperature & then set
into a new form.
This type of set is
maintain in normal use
of material however the
setting is lost when the
material is subjected to
severe condition of use.
For ex:- hot washing or
steaming of material above
Tg.

10. PERMANENT HEAT SETTING
• This type of heat
setting involves
change of internal
morphology of the
material in such a
way that it would not
revers till the
material is destroyed
by taking it above it’s
melting point.

11. Heat Set Temperature of some Fibres
Fibre Min T. °C Max. T. °C Time (in seconds)
Polyester (PE) 170 210 15-50
Polyamide PA 6.6 170 210 15-40
Polyamide PA 6 160 180 15-40
Triacetate 160 180 15-40
Acrylic (PAC) 160 180-200 15-40
Elastomers 170 180-200 15-40

12. Mechanism used for Heat Setting
Machines used: Stenters.
 Fluctuating temperatures inside the stenter cause a consistent variation of
crystallinity in the fibre structure, which leads to different affinity for dyes.
 The moisture in the fibre produces soft hand, but variable moisture
percentages in the different fabric sections create the above mentioned defect
(variable crystallinity).
 Too low temperatures do not allow a good setting while too high
temperatures and too long
 setting times cause yellowing (PA and elastic fibres), stiff hand (acrylics), and
loss of elasticity (elastic fibres).

13. Mechanism used for Heat Setting
 5. The presence of combustion gas (NOx) produces a yellowing of
the elastomers.
 6. The heat setting process carried out before scouring could fix
the stains on the fabric or make the scouring process more difficult
due to the modification of the lubricating products (cracking with
emission of polluting gas).
 7. Heat setting after dyeing could lead to the sublimation of
disperse dyes (if not accurately selected).

14. Points of Concern
 Heat setting reduces polyester's dye up take. Heat -set goods dye lighter and
slower than non heat -set good.
 For uniform shades, side to center, front to back and beginning to end exposure
to heat must be controlled and uniform, otherwise these differences will show
up in the dyed cloth.
 Heat - setting can be done either at the end of wet processing or at the
beginning.
 At either point, the goods must be free of wrinkles and other distortions
otherwise the distortions will be permanently set.
 Care must be taken when heat -setting greige goods sized with polyvinyl
alcohol.

15. PointsofConcern
 At high temperatures, PVA will dehydrate, becoming discolored and
insoluble in water.
 While greige heat -setting may be particularly beneficial when
preparing easily distorted fabrics, one may have to settle for less than the
full heat -setting benefit in order to still remove the size.
 For these cases, alternate mechanical handling preparation equipment
may be the answer.
 Heat -setting harshen the hand and stiffens the fabric. The condition is
more prone to happen when contact heat is used.
 The fabric may become flatter and develop an unwanted gloss or sheen.

16. References
• Book- VB Gupta & VK Kothari.
• http://www.slideshare.net/sheshir/heat-
setting?qid=51840e8d-4fdc-4c2f-a012-
753c10478363&v=&b=&from_search=1
• file:///D:/Forms,%20Results%20&%20docs/SEMINAR/NPTEL
%20__%20Textile%20Engineering%20-
%20Textile%20chemical%20Processing_%20Theory%20and
%20practice%20of%20Preparatory%20Processes.html

17. ThankYou!