Geraniol and natural rubber

1. Maria Johny
GERANIOL AND NATURAL RUBBER

2. Topics Covered
Geraniol -
Introduction
Chemical reactions
Uses
Natural rubber -
Introduction
Coagulation process
Marketable forms
Latex processing methods
Structure of rubber
Rubber Processing
Uses
Points to remember

3. Geraniol

4. It is an acyclic monoterpenoid
alcohol.
It occurs in a large number of
essential oil, particularly in rose oil.
Geraniol and nerol ( naturally
occurring alcohol) are geometrical
isomers

5. Oxidation Reduction
1 2 3
Cyclisation

6. α

7. Oxidation
On oxidation with mild oxidizing agents geraniol forms
geranial which on further oxidation gives geranic acid.

8. Reduction

11. white or
slightly
yellowish
liquid

13. 35% rubber hydrocarbons
1
60% water
2
2.5% sugar & other resinous
materials
4
2- 2.5% proteins
3
latex
Composition

14. Title Page with Photo
Write a date or subtitle

15. Bacteria in air also attacks protein membrane
to produce lactic acid. Therefore, when left
overnight, these lactic acid produces hydrogen
ions and causes latex coagulation.
Alkali such as ammonia solution added to
latex. Hydroxide ion from ammonia neutralise
the hydrogen ion from lactic acid.

17. preserved field latex & latex
concentration
sheet rubber
crepe rubber
block rubber
Crop
Marketable forms
latex (80%)
Field coagulum
(tree lace, shell
scrap, earth scrap)
Rubber

18. Latex can be processed into any of the form. But field coagulum
rubbers can be processed only into crepe or block rubbers.
Latex with suitable preservative ( eg: ammonia ) - preserved field latex.
Latex concentration is carried out by increasing gravitational force of
rubber particles
1. Centrifugation - By centrifugal force.
2. Creaming - By adding creaming agents like ammonium alginate
For processing into sheet rubber
Latex is coagulated using formic acid in suitable containers into thin
slab of coagulum and sheeted through smooth rollers followed by
grooved set and dried.
( Depending on drying )

19. When coagulated latex or any form of field coagulum rubber is passed
through several times through a minimum of 3 mills with heavy rolls , a
crinkly lace like rubber is obtained and it is dried - Crepe rubber
Types of crepe rubber
• Pale latex crepe ( PLC)
• Sole crepe
• Estate brown crepe (
EBC)
• Remilled crepe
• Smoked blanket crepe
• Flat bark crepe
Processing of natural rubber
into block rubbers
• Size reduction
• De- watering
• Dirt removal
• Drying
• Baling
• Grading

20. Latex Processing Methods
Latex concentration by centrifugation
Latex concentration by creaming
Latex processing into sheet rubber

21. Production of NR concentrate by
centrifugation
Preserved
field latex
>
Bulking and
testing of
field latex
Continuous
centrifuging
Concentrate
storage
Concentrate
ammonium
and testing
Skim latex processing
to crepe rubber
>
>
>
>
Centrifugation
1 2 3
4
5 6

22. Field latex
Adding creaming agents
Allowing latex to
separate
Upper layer
concentrated latex (50-55% drc)
Latex
concentration
by creaming
Lower layer
Serumcontaining verylittle latex

23. Latex processing into sheet rubber
Latex
Strained through
40 and 60 mesh
stainless steel
sieves
Drc is
estimated
Diluted
( consistency of
½ kg of dry
rubber for every
4 L of diluted
latex )
Transfer
latex
bulking
tanks
Allow to stand
(15-20 min)
to settle heavy
dirt particles
Transfer
diluted latex
to
coagulation
pans
Dil. Formic
or Dil.
Acetic acid
is added
Coagulation
Coagulum is
washed with
water
Coagulum is
sheeted (3 mm
thickness )in
sheeting battery
or smooth rollers
Passed
through
grooved
roller
wet sheet to drip
under shade for 4-6
hrs
Sheet is
transported to
smoke house with
temp b/w 40° &60°c
Completely
dried sheet

24. Structure of rubber
n = 3000 - 5000

25. Destructive
distillation of rubber
Isoprene
( major product)
Rubber is a polymer of
isoprene & (C5H8)n
Structure Elucidation
Osmotic pressure, viscosity,
ultra centrifuge measurements
Molecular weight is of order
2,00,000 - 4,00,000
Halogens & halogen acid readily
react with rubber.
Hydrogenation of rubber give
fully saturated hydrocarbons.
Rubber form ozonide, ( C n
H
5 8O3 )
Unsaturated compound
Formulae of addition products
One double bond for each
isoprene unit present

26. Ozonolysis
of rubber
Laevulaldehyde, it's
peroxide, laevulic acid - (
major product by
pummerer) - 90%
small amount of carbon
dioxide, formic acid and
succinic acid
This is
explained only
if the structure
is composed of
isoprene unit
joined head to
tail

27. Rubber Processing
Raw rubber
Rubber compound
Vulcanize rubber
Masticating process
Compounding
Vulcanisation process

28. Reduce molecular weight
Reduce the viscosity
To soften the raw rubber
Mastication of
rubber
It is mechanical shearing
process using two roll mill to
After mastication - The processing
will be much easier and increased
the effectiveness of the dispersion
of compounding ingredients
The speed of the two rolls are usually different,
the front roll having a slower speed. For natural
rubber mixing, fraction ratio of 1:1.2 for front to
back roll is used.

29. •
•
•
•
•
•
Rubber compounding

30. Vulcanisation of rubber
The process of treating rubber with sulphur and
heating is called vulcanisation.

31. During this process, sulphur react with rubber
molecules to effect crosslinking as follows
To speed up the process, accelerators are added.
For example :mercaptobenzothiazol (MBT),
teramethyl thiuram disulphaide (TMTD) and zinc
diethyldithiocarbamate (ZDC)

32. Hard
More elastic
More heat resistant
High melting point
High tensile strength
Soft
Less elastic
Non heat resistant
low melting point
low tensile strength
Natural rubber Vulcanised rubber

33. Uses
In automobiles ( tyres, tubes,etc...)
Mixtures of latex cement and rubberized bitumen for
tarring roads.
Insulators for electrical appliances and cables.
Friction enhancers such as shoe soles and door
stopper.
Rubber caps, rubber band, gloves, adhesives, pipes and
tubing.

34. Points to remember
Structure of geraniol & nerol
Reactions of geraniol
Latex concentration methods
Vulcanisation of rubber