This document discusses different types of fibers used in surgical dressings. It begins by defining fibers and describing their origins from animal, vegetable, mineral or synthetic sources. Key fibers discussed include cotton, wool, rayon and their structures and production processes. The document emphasizes that the quality of surgical dressings depends on the fiber used and describes properties important for wound care like absorbency and strength.

2.  Fibers are fine hair like structures of animal,
vegetable, mineral or synthetic origin
 They can be defined as “elongated thick
walled cells, with pointed ends.”
 The quality of surgical dressings depends
upon the type of fiber used to prepare
dressings.

3.  Dressings make direct contact with the
wound
 Bandages used to hold dressings in place.
 However B.P classify them as same thing.

4.  Commercially available fibers have
diameters ranging less than 0.004 to 0.2mm.
 The fibers used for surgical dressings have
shorter length.
 For textile use. Fibers must have length of at
least 1000 times to its diameter.

5.  They may be of different forms.
a) Staple or chopped: they are short fibers.
b) Monofilament: it is continuous single fiber.
c) Tow: it is untwisted bundles of continuous
filaments.
d) Yarn: it is twisted bundles of continuous
filaments.

6.  These are classified based upon their origin.
These include:
1. Animal fiber
2. Vegetable fiber
3. Regenerated fibers
4. Mineral fibers
5. Synthetic fibers

7.  They are obtained from animals.
 All animal fibers are complex proteins.
 They are resistant to most organic acids and
to certain powerful mineral acids such as
H2SO4.
 They may be damaged by mild alkalies and
may be dissolved by strong alkalies such as
sodium hydroxide.
 E.g. Silk and Wool

9.  They are obtained from plants and are
generally based on the arrangement of
cellulose, often with lignin.
 These fibers are mainly made up of
cellulose.
 They resist alkalies and most organic acids.
However they are dstroyed by strong mineral
acids.
 There are four major types of vegetable
fibers:

10. i- Seed Fibers
 These are the soft hairs that surround the
seeds of certain plants e.g. Cotton, Kapoka
(Ceiba) etc.
ii- Bast fibers
 These are the tough fibers that grow
between the bark and the stem of many
dicotyledonous plants e.g. Flax, Hemp, Jute
and Sunn etc

12. iii-Vascular fibers
 These are the tough fibers found in the
leaves and stem of monocotyledonous e.g.
Agave (sisal), Henequen etc.
iv-Grass stem fibers
 They are obtained from entire stem of some
grasses and straw, such as esparto.

14.  They are prepared from naturally occurring
polysacchrides e.g. cellulose.
 The cellulose is modified to prepare a
suitable fiber form. It is prepared by
dissolving the cellulose in chemicals and
making it into fiber again.
Examples are Viscose, cellulose acetate,
oxidized cellulose, nitrocellulose etc.

16.  They are obtained from minerals.
 Examples include Glass fibers, asbestos
fibers and aluminium fibers.

18.  These are produced by polycondensation of
organic molecules i.e. cellulose
 These are stronger than natural fibers e.g.
nylon, terylens and polyethylene etc.

19.  Fibers can be distinguished by chemical
tests and by studying their microscopic
structures.
 Synthetic and mineral fibers give negative
tests of vegetable and animal fibers.

20.  Biological source: Gossypium herbeceum
 Family: Malvaceae
 Parts used: hairs and epidermal trichomes of
seeds of small trees and shrubs
 Habitat: majorly grown in india for atleast
5000 years. From india, it spread to China,
Egypt and USA and now cultivated there as
a crop.

21. Half of the cotton of the world is produced in
USA and the other important sources are
Egypt, India and Pakistan.
 Preparation: plants are shrubs or small trees
producing capsules containing numerous
small seeds. Capsules open upon maturity
and seeds get exposed. Seeds are covered
with mass having long white hairs or cotton
fibers called “lint”. Cotton fibers are collected
in the absence of rain and dew drops and
dried in shade. After drying, they are

22. ginned to remove the hairs from the seeds.
Seeds are again subjected to another type of
gin which is used to separate smaller hairs
called “Linters” from the seeds. These short
hairs are used to make cotton wools while
seeds are used in the preparation of cotton
seed or cattle cake. The cotton obtained is
called raw cotton which have various impurities
such as broken seeds, fragment, leaves etc.
most of these impurities are removed during
manufacturing of yarn.

23.  Structure and characters: cotton consists of
unicellular hairs. Each of these hairs is
flattened, tabular with spiral twist. The length
of fiber is upto 5cm with a diametet of 9-24
micrometer. The number of twists in the
indian, pakistani cotton fibers is 75 per cm.
USA cotton fibers have 150 twists per cm.
hair has cellulose wall which is covered with
waxy cuticle layer. Due to the presence of
cuticle it is non-absorbent.

24.  Identification test:
1. On ignitin, cotton burns with a flame, giving
little odour of burning leaves and fumes. The
ash leftovers easily crumbles. Small samples
of burning cotton can be blown out as in
candle.
2. Raw cotton dissolves in copper oxide
ammonia solution (cuoxam) forming a blue
color.
3. Raw cotton is soluble in cold sulphuric acid
80% w/w.

25. 4. Raw cotton is insoluble in warm HCL, in
5%potassium hydroxide solution and in
acetone.
5. It is insoluble in 90% formic acid or 90%
phenol.
6. When raw cotton is treated with cold
shirlastain-A for one minute, it gives blue or
purple color after washing.
7. When raw cotton is treated with cold
shirlastain-C for minutes, it gives mauve to
reddish-brown color after wahing.

26.  Chemical constituents:
Cellulose 91%
Wax and fat 0.4%
Protoplasm and other cell contents 0.6%
Ash 2%
Moisture 7.8%

27.  Uses:
1. raw cotton is used as filtering medium
2. It is a chief constituents of many surgical
dessings and insulating materials.
3. Used in textile industry
4. Used to manufacture explosives, cellulose
acetate and other cellulose derivatives.

29.  Synonyms: absorbent wool, purified cotton.
 Botanical source: Gossypium herbceum and
other species of Malvaceae family.
 Family: Malvaceae
 Parts used: epidermal hairs of seeds of
plants of Malvaceae family
 It is made from cotton waste i.e. fibers or
hairs (comber waste, linters, sardstrip or
cardfly) which are rejected or seperated

30. By cotton combing machine during the
preparation of cotton for spinning (to draw out
and twist into threads)
 Preparation: following steps are involved;
S1: remove impurities from comber waste
firstly.
S2: comber waste is heated with dilute sodium
hydroxide solution and soda ash (Na2CO3)
solution at 1-3 atmospheric pressure for 10-15
hours. Most of the fatty cuticle is removed and
the trichome wall becomes absorbent in this
process.

31. S3: in this step, the cotton is washed with water,
decolorizd with sodium hypochlorite solution and
treated with dilute HCl and than dried.
S4: the dried fibers are in matted condition i.e.
twisted together into a thick mass, so they are
opened up by machines.
S5: in this step the absorbent cotton is converted
into thin continuous sheets with the help of a
carding machine. Several sheets are placed upon
one another and paper is kept between the two
sheets. Finally they are packed into rolls and
sterilization.

32.  Chemical tests: same as that of raw cotton.
 Characters: absorbent cotton occurs as
white, soft, fine hairy filaments. The filaments
consists of unicellular hair of 2.5-5cm in
length. The diameter is 9-24 µm. Hairs are
cylindrical when young and becomes
flattened and twisted at maturity. The
number of twists varies from 75 per cm to
150 per cm for different species. Absorbent
cotton is odorless and tasteless.

33.  Chemical nature:
Absorbent cotton consists of cellulose.
Cellulose is compose of a number of glucose
units linked together by beta 1, 4 glucosidic
bonds.
 Uses:
a) Absorbent cottons is used for surgical
dresssings e.g, it is used to absorb blood,
mucus, pus, and for mechanism support.
b) As it is sterlized and purified, therefore used
to protect wound from bacteria.

34.  Synonyms: animal wool or sheep’s wool.
 Biological Source: Zoological name is Ovis
arries
 Family is Bovidae.
 Parts used: Wool obtained from the fleece of
domestic sheep
 Geographical Source: Wool producing
countries include; Australia, Russia,
Argentina, India and America.

36.  Preparation: The fleece of sheep is generally
cut once in a year, usually in the spring or early
summer. Wool from the different parts of the
same fleece varies greatly in length of fibers,
fitness and structure. Wool from shoulders and
sides of the sheep is usually superior to that
from other parts of the body.
The following steps are involved in the preparation
of wool.
S1: the hairs are removed from the fleece of the
sheep. As the length and quality of the hairs
varies, so they are spread on a frame, covered
with wire netting to separate it into wool of
different sizes and qualities.

37. S2: the fibers are beaten over the netting to
remove dust and dirt. The other foreign
substances are also removed.
S3: in this step, fibers are cleaned because it
contains an oily substances i.e. wool grease.
So the wool is washed in tanks containing
warm, soapy water to remove the wool grease.
S4: the wool is dried by hot air. The fibers are
loosened and drawn straight into a

38. continuous from with the help of carding
machine. This process is known as carding.
Finally these fibers are spun into yarn.
S5: The wool grease from washing process is
collected by mechanical means or by or
organic solvents. Purified wool grease is
known as “wool fat” or anhydrous lanolin. It is
used in cosmetics and ointments.

39.  Structure: wool consists of elastic, shiny and
smooth hairs or fibers. The length of hair is from
2-50cm.
Under microscope, the hair can be distinguished
into three regions;
a. Cuticle; consists of epithelial scales which are
lying over each other like “tiles”. Strong
solution of ammonia can separate the epithelial
scales in a few minutes.
b. Cortex; consists of elongated cells.
c. Medulla; consists of rounded cells containing
fatty matter or pigments.

40.  Characters:
 A single wool fiber can resist breakage when
subjected to weight of 15-30g and when
stretched as much as 25-30% its length.
 Wool is insoluble in warm HCl and in cold
concentrated H2SO4.
 Wool fiber has great affinity for dyestuffs. It
can absorb 17 times of moisture of its
weight.

41. It has good resistance to dry-cleaning solvents,
strong alkalies and high temperatures.
Wool fiber may be damaged by ageing, larval
attack such as cloth moths, carpet beetles and
exposure to sunlight.
It does not continue to burn when removed
from a flame

42.  Identification tests:
Wool is insoluble in warm HCl and in cold
concentrated H2SO4.
they respond positively with Millon’s test i.e.
wool gives thick red color with Millon’s reagent
on gentle heating.
They are stained permanently with picric acid.
With picric acid it gives deep yellow color.

43. They are dissolved in 5% aquous potassium
hydroxide solution.
Wool gives blue color when treated with
ammonia copper oxide solution.
When lead acetate is added to a solution of
wool in caustic soda, black precipitates are
formed.

44.  Chemical constituents:
Raw wool consists of;
 Woo fibers….. 31% (wool fibers are composed
of protein called keratin which is rich in maino
acid cystine. Keratin consists of C,H,O and N
elements. It gives strength and elasticity to the
wool fiber and thus the fiber can be stretched to
an extent).
 Wool sweat or suint….. 32% (suint is an oily
substancecomposed of potassium salts of fatty
acids.
 Dirt and dust….. 25%
 Wool grease or lanolin.

45.  Uses:
 wool is used in pharmaceuticals as filtering
and staining medium.
 Used to prepare crepe bandages.

46.  An artificial textile material composed of
cellulose obtained from cotton linters or from
the pulp (soft and fleshy part) of the trees such
as Spruce (an evergreen tree of the pine
family).
 In other words, rayon is regenerated cellulose
or fibers.
 Regenerated fibers are prepared from naturally
occuring polysacchrides.
 These compounds are modified to yield a
suitable fiber form.

47.  Preparation:
Can be prepared by two processes.
1. Viscose process
2. Cuprammonium process.
1. Viscose process
The process was introduced by three British
chemists Baedle, Bevan, Cross in 1892.
In this process the starting material is cellulose
obtained from the crushed wood of Spruce or
from Cotton linters.
The following steps are involved in this
process.

48. S1: the wood of Spruce is delignified to
produce white pulp. The pulp contains 80-90%
of cellulose and some hemicellulose.
S2: as hemicellulose are alkali soluble
therefore it is removed by treating product with
NaOH. The remaining alkali cellulose is
dissolved in a mixture of carbon disulphide
and sodium hydroxide solution to form a
viscous yellow liquid Viscose. The liquid is
allowed to ripen and filtered.
S3: in this step the filterate is forced through
small holes in a nozzle into liquid bath.

49. The bath contains dilute sulphuric acid and
sodium sulphate. The cellulose is regenerated
in the form of continuous filaments in the bath.
This process is called Extrusion.
S4: the filaments are spun into yarns. The
yarns are combined, twisted and treated with
sodium sulphide to remove free sulphur. After
desulphurization, the yarns are bleached
washed, dried and a 10% moisture content is
adjusted. Surgical dressings are prepared from
the viscose yarns.

50. 2. Cupramonium Process
In this process purified cellulose is treated with
cupramonium liquor then with sodium
hydroxide to form viscose. The remaining
steps are the same as that for viscose process.
Delustring and Dying
Delustring is done, when the fibers are used for
surgical dressings. The fibers can be
delustered by the addition of white pigment i.e.
titanium oxide to the solution before
preparation of yarns. The

51. delustered viscose also called mall viscose is
used to prepare surgical dressings. Similarly
the fibers may be dyed by the addition of
suitable dye instead of titanium oxide.
Preparation of Cellophane
when viscose soultion (formed in step 2) is
passed through a nozzle into a regenerating
bath, sheets of viscose are formed. These
sheets are washed bleached, treated with
glycerin solution and dried to produce
cellophane.

52. Cellophane is a valuable packing material and
is also used as dialyzing membrane. It is also
used as protective dressing.
 Characters
 Viscose is pure form of cellulose.
 It is white lustrous in color.
 Its molecule contains 450 residue units
whereas the molecules of wood cellulose
contains 9000 glucose units.
 Viscose fibers are solid, transparent, 15-
20µm in diameter and slightly twisted.

53.  Identification tests
On ignition, rayon burns with a flame, giving
little odor and fumes, it does not produce bead
and leaves a small white ash.
A blue color is produced, when rayon is
moistened with a mixture of iodine and
sulphuric acid.
Rayon dissolves in copper oxide ammonia
solution (cuoxam) forming a blue color.
Rayon is soluble in cold sulphuric acid 80%
w/w.

54. Rayon is insoluble in warm HCl, in 5%KOH
solution and in acetone.
It is insoluble in 90% formic acid or 90%
phenol.
When rayon is treated with cold shirlastain-A
for one minute, it gives blue or purple color
after washing.
When rayon is treated with cold shirlastain-C
for 5 min, it gives violet to reddish-brown color
after washing.
It does not produce red color, when treated
with phloroglucinol and HCl.

55.  Uses
Viscose rayon is used to prepare fabrics,
surgical dressings, absorbent wool, enzyme
and cellophane.
It has advantage over cotton dressings in that
they show no less of absorbance on storage.