Viscose rayon is a manufactured fiber made from regenerated cellulose. It is produced through a process involving treating cellulose pulp with chemicals to create a viscous solution called viscose, which is then forced through spinnerets into an acid bath to harden into filaments. Viscose rayon is inexpensive to produce, with properties similar to cotton. It can be used to make fabrics for apparel, home furnishings, and nonwoven materials.

1. Viscose Rayon

2. Rayons
According to FTC (Federal trade
commission):
A manufactured fiber composed of
regenerated cellulose in which
substituent have replaced not more
than 15 % of hydrogen of hydroxyl
groups

3. Viscose Rayon
 Rayon is the oldest commercial manmade
fiber.
 The process of making viscose was
discovered by C.F.Cross and E.J.Bevan in
1891
 It is now manufactured abundantly as its
raw material is cellulose and is available in
large quantities in timber and vegetable
matter

4. Viscose Rayon
 The viscose method is relatively
inexpensive and of particular significance in
the production of nonwoven fabrics.
 It is not synthetic.
 Its properties are more similar to cotton and
flax rather than polyester and nylon.
 Viscose Rayon has silk like aesthetic and
good feel.
 The name viscose was derived from the
word viscous, which mean liquid state of
spinning solution.

5. Manufacturing of viscose
rayon
 Preparation of wood pulp
 Steeping and pressing
 Recovery of Caustic soda
 Shredding
 Aging
 Churning (Xanthation or Sulphidising)
 Mixing
 Ripening
 Spinning

7. Preparation of Wooden pulp
 Soft wood trees are used
 Wood is chipped into pieces about
0.9’’ X 0.5’’ X 0.25’’
 Chips are treated with Calcium bi sulphite
Ca(HSO3)2 for 8 -12 hours
 Chips are cooked with steam under
pressure for 14 hours to convert into pulp
form
 Pulp is washed with water to remove
Calcium bi sulphite
 Pulp is bleached with sodium hypo chlorite
(NaOCl) solution
 Pulp is converted into paper board

9. Steeping and
pressing
 The cellulose pulp sheets are steeped
in 17.5 % NaOH solution for 1-4 hours
 It is then pressed to remove excess
solution
 This process is called “ steeping”
 Cellulose is swollen and liquid turn
brown
 Excess of alkali is pressed out
 This process is known as “ pressing”
 Moist soda cellulose mass is obtained

10. Recovery of caustic soda
 Moist soda cellulose is allowed to
diffuse through parchment
membranes to obtain pure caustic
soda
 Recovery of caustic soda is important
for economic purpose
 Used Caustic soda is concentrated
and mixed with fresh caustic soda to

11. Empirical formulae of cellulose =
(C6H10O5)n
Steeping:
(C6H10O5)n + NaOH = [C6H9O4-ONa]n
(Soda cellulose)
Xanthation:
[C6H9O4-ONa]n + nCS2 → [C6H9O4-
OCS2Na]n

12. Shredding
 The shredding machine consists of
drum inside which high speed
revolving blades with serrated edges
are installed
 Moist soda sheets are shredded and
converted into fine crumbs

13. Shredding Machine

14. Ageing
 Carried out in stirring vessel
 Very important for properties of fabric
 Polymeric chains of cellulose are
degraded in the presence of
atmospheric oxygen at temp 20-25
degree centigrade
 Completed in 1-2 days

15. Churning
 Stainless steel air-tight rotating drum
 It can rotate at about 2 rpm
 Soda cellulose crumbs contain about 30%
cellulose
 10% CS2 solution is added to soda cellulose
crumbs
 Soda cellulose and CS2 are churned
together to form deep orange gelatinous
mass of sodium cellulose xanthate
 Churning is completed after 3 hours
 After completion of churning, sodium
cellulose xanthate is discharged

16. Mixing and blending
 Dilute NaOH soln is added in sodium cellulose
xanthate and mixing is carried out for 4-5 hours
 A clear viscous liquid is obtained which is
known as viscose
 Viscose contains 6.5 % NaOH and 7.5 % of
cellulose
 Different viscose solutions obtained from
different mixers are blended together along with
TiO2 to balance inequalities and to obtain

17.  Uniform homogeneous mixture produces
better quality of Rayon
 It is filtered to remove any un dissolved
particles
 Air bubbles are removed

18. Ripening
 It is very important part of manufacturing
process
 The uniform homogenous viscous solution
is stored in stainless steel vessel at 10-18
◦C for 4-5 days for ripening
 During ripening, first of all the viscosity of
solution falls down and then again reaches
to its original viscosity

19.  When original viscosity reaches, this is
the proper time to spin the solution
and solution is immediately spun

20. Spinning
 A ripened viscose solution is forced to a
centrifugal pump by compressed air, which
delivers it to filtering media and then glass
tubing which carries a spinneret jet
 The centrifugal pump delivers the viscose
solution constantly and regularly
 The spinneret is submerged in acid bath
 Viscose solution comes out into acid bath
after passing through “spinneret” solidifies
into filaments owing to regeneration of
cellulose
 Temp. of acid bath = 40~55 ⁰C

21. Longitudinal view

22. Cross sectional view

24. Properties of viscose rayon:
Tensile strength:
The tensile strength of normal viscose
rayon is 30000 – 46000 lbs per square
inch.
Elongation:
Normally it will elongate 17-25 % of its
original length before breaking.

25. Elastic properties:
At 2% extension it has elastic recovery of
60%
Specific gravity:
1.50 to 1.52
Effect of moisture:
It has moisture regain of 13%.

26. Effect of heat:
It begins to lose strength at 150
degree centigrade and decomposes at
205 degree centigrade.
Effect of sunlight:
It can withstand exposure to sunlight
without discoloration.

27. Chemical properties:
It can be attacked by oxidizing agents
like hydrogen peroxide.
Effect of Acids:
Can be attacked by hot dilute acids
and cold concentrated acids.
Effect of alkali:
It has high resistance to dilute alkali
and can be attacked by strong alkalis.

28. Resistance to insects:
Resistance to insects is good but can
be attacked by silver fish.
Microorganisms:
Resistance to mildews is much better
than cotton.

30. Major uses of Rayon:
 Apparel: Accessories, dresses,
jackets, sport shirts, sportswear,
suits, ties, work clothes etc.
 Home Furnishings: Bedspreads,
blankets, curtains, sheets,
tablecloths.