Upgrading of PVC as an important engineering ma

1. CORPORATE TRAINING AND PLANNING
Polyvinyl Chloride
 Polyvinylchloride (PVC) is the world’s most versatile
thermoplastics with a wide range of applications than any
other plastics.
 It plays an important role in every field such as
agriculture, electrical, irrigation, house roofs, shoe soles
and many other fields .
 It is having limited thermal stability.
Introduction
Polymerization
CH2=CH CH2-CH
Cl
Cl
n
n

2. CORPORATE TRAINING AND PLANNING
Polyvinyl Chloride
Introduction
 Vinyl Chloride was first synthesized and reported by
Reghawlt in 1835 .
 The first report of polyvinyl bromide was published by
Hoffmann in 1860.
 The full scale commercial production of PVC resin began in
1931 in Germany.
 In India the manufacturing of PVC began in 1961 when
Calico started its plant in Mumbai.

3. CORPORATE TRAINING AND PLANNING
Preparation of Monomer
Commercial Method
- Vinyl chloride monomer is prepared by cracking 1,2-dichloro
ethane.
- Vinyl Chloride may be produced by the addition of HCl to
acetylene.
CH2-CH2 CH2=CH
Cl Cl
Cl
+ HCl
HC CH + HCl CH2=CH
Cl
+ 95.5 KJ/mol

4. CORPORATE TRAINING AND PLANNING
Polymerization
 Suspension Polymerization
 Emulsion Polymerization

5. CORPORATE TRAINING AND PLANNING
 About 85% of the world’s PVC production are by
suspension polymerization.
 Dr. Berg at Wacker-Chemie Polymerization developed
this technique in 1935.
 Vinyl chloride is dispersed in water with stirring.
 Monomer soluble organic peroxides are used as initiators.
 Protective collides such as Cellulose ethers are added to
prevent the monomer droplets from coalescing.
 After the polymerization reaction, unreacted vinyl chloride
is removed and is passed to monomer recovery plant.
 The polymer is then centrifuged to remove free water and
resulting wet polymer is dried by hot air.
 The particle size of PVC resin is about 100-150µm.
Suspension Polymerization

6. CORPORATE TRAINING AND PLANNING
Suspension Polymerization
Vinyl chloride
monomer
Water
Suspending
agent
Polymerization
Vessel
Stripping Centrifuging
Water
Drying
Water
PVC

7. CORPORATE TRAINING AND PLANNING
Emulsion Polymerization
 The system consists of the monomer- water containing
emulsifier and water soluble initiator.
 In presence of the emulsifier, agitation of the charge in the
autoclave disperse the monomer into very fine droplets.
Initiator starts polymerization.
Monomer-Water containing
Emulsifier Conc(2-3%)
Water soluble initiator
Autoclave
Drying
Grinding
Final Size
Classification
Packing

8. CORPORATE TRAINING AND PLANNING
Structure Property Relationship
- PVC is polar in nature due to presence of C-Cl dipole.
- Resistant to non- polar solvents.
- Flame retardant and self extinguishing.
- Presence of chlorine atom causes an increase in inter
chain attraction and increase hardness and stiffness of
polymer.
CH2-CH
Cl
n

9. CORPORATE TRAINING AND PLANNING
Properties of Poly Vinyl Chloride
Name Value Unit
Specific gravity 1.18-1.70 --
Tensile Strength 5.5-26.2 MPa
Tensile modulus 4.8-12.4 MPa
Flexural modulus 30 MPa
Elongation at break 150-450 %
Hardness A85 ---
Glass transition temperature 80-85 °C
Dielectric Strength 9.9-15.8 KV/mm

10. CORPORATE TRAINING AND PLANNING
Dilute Solution Viscosity
(K Value Of PVC)
 PVC is heat sensitive material and therefore instead of
melt flow index, K-value is calculated.
 The K-values of PVC for processing lie between 55
and 60.
 Higher K-values lead to better mechanical and
electrical properties of the moulded material at the
cost of decreasing processibility.
 Optimum results can be achieved in each type of
processing using products of suitable K-value.

11. CORPORATE TRAINING AND PLANNING
The value of ‘k’ is calculated by the relationship
Log10 ηrel = 75 k2 x 10-6
+ (k x 10-3) C
1+ 1.5 kc x 10 -3
ηrel = relative viscosity = η/ ηo
k = k-value
C= concentration in gm/ml.
From K-value one will know the grade of PVC material
K-Value 60-65 Injection Moulding
65-67 Extrusion Process
67-70 Calendaring Process
Dilute Solution Viscosity
(K Value Of PVC)

12. CORPORATE TRAINING AND PLANNING
Additives and Compounding
A PVC compound may contain the following ingredients.
- Polymer
- Stabilizers
- Plasticizers
- Polymeric Processing Aids
- Impact Modifiers
- Fillers
- Pigments
Some other miscellaneous materials include flame (fire)
retardants, optical bleaches and blowing agents.

13. CORPORATE TRAINING AND PLANNING
Stabilizers
- Heating of PVC at temperature above 70°C has a
number of adverse effects on the properties of the
polymers. Sufficient degradation may take place
during standard processing operations (150-200°C)
making the product useless.Therefore to avoid
degradation ‘stabilizers’ are found useful.
- The compounds of Cd, Ba, Ca and Zn are
prominent as PVC stabilizers.

14. CORPORATE TRAINING AND PLANNING
Plasticizers
Plasticizers are used
- For reducing processing temperature of polymer
below the decomposition temperature.
- To modify the properties of finished products such as
flexibility.
- To modify processability.
All PVC plasticizers have a solubility parameter to that of PVC.
Di-iso-octyl phthalate (DIOP) and di – ethyl
hexylphthalate (DEHP) are most important plasticizers
used in PVC.

15. CORPORATE TRAINING AND PLANNING
Extenders
- Sometimes plasticizers are not found useful in PVC
because of their limited compatibility with the polymer.
- When mixed with ‘true plasticizer’ (commercially called
extenders), a reasonable compatibility is acquired.
- Extenders are cheaper than ‘plasticizers’.
- Plasticizers can often be used along with ‘Extenders’
without any adverse effects on the properties of
compound.
Commonly used extenders in PVC are
- Chlorinated paraffin waxes
- Chlorinated liquid paraffin fraction
- Oil extracts

16. CORPORATE TRAINING AND PLANNING
Lubricants
- Two types of lubricants are generally used in PVC
- internal lubricants and external lubricants.
- External lubricants prevent sticking of the compound to
the processing equipments by forming a film
between the bulk of the compound and the metal
surface of the processing equipment.
- Internal lubricants improves flow behaviour of the
materials.
- Calcium Stearate, normal Lead Stearate, Dibasic Lead
Stearate, Graphite are employed to improve flow
properties.

17. CORPORATE TRAINING AND PLANNING
Fillers
Fillers are commonly employed in order to reduce cost.
They may also be incorporated for technical reasons
such as;
 To increase the hardness of a flooring compound,
 To reduce tackiness of highly plasticized compounds,
 To improve electrical insulation properties
 To improve the hot deformation resistance of cables.
For electrical insulation, china clay is commonly
employed while various carbonates are used for general
purpose work.

18. CORPORATE TRAINING AND PLANNING
Pigments
To add a pigment, firstly the following facts are to be
considered
- Will it decompose, fade or plate out?
- Will the pigment adversely affect the
functioning of stabilizer and lubricant.
- Will it fade, bleach out or will it bleed.
- Will the pigment adversely affect properties that are
relevant to the end usage (because many pigments
will reduce the volume resistivity of a compound).

19. CORPORATE TRAINING AND PLANNING
Polymeric Impact Modifiers & Processing Aids
- Unplasticized PVC has a high melt viscosity leading to
some difficulties in processing. The finished product is also
too brittle for some applications. In order to overcome
these problems ‘impact modifiers’ are generally added.
- Impact modifier are semi-compatible and often somewhat
rubbery in nature.
- Examples for Impact modifier are ABS graft copolymers,
Methacrylate – butadiene - styrene (MBS) terpolymers,
Chlorinated Polyethylene, EVA-PVC graft polymers.
- Chlorinated Polyethylene is being widely used as an
‘impact modifier’ particularly where good aging properties
are required.

20. CORPORATE TRAINING AND PLANNING
Formulations
The formulation given below is intended as a
general guide but not for a specific application
(Flexible Pipe).
Suspension polymer ( K- 65) 100
DIOP 40
Trixylyl Phosphate 20
China clay 20
Tribasic lead sulphate 7.0
Stearic Acid 0.5
Pigment 2.0

21. CORPORATE TRAINING AND PLANNING
Compounding of PVC
 This is the most important operation in the PVC
processing where the PVC resin is formulated into
a compound with the desired properties with
respect to processing and end product by addition of
selected additives. Adding and mixing additives into
plastics is an integral part of a much broader operation
called compounding in which ingredients including the
colorants are intimately mixed together into a
nearly homogenous mass.
Compounding operation can be classified into following two
Categories;
 Melt blending , where the mix is fluxed or fused.
 Dry blending, where the resultant compound is a dry
relatively free flowing powder containing the liquid
ingredients absorbed on the polymer particles.

22. CORPORATE TRAINING AND PLANNING
Melt compounding
 In this process a premix is prepared which is then
fluxed.
 The fluxed mixture is made into pallets and fed to
process equipment.
 Simple mixers like ribbon or tumble blenders are used
for the preparation of premix of the ingredients.

23. CORPORATE TRAINING AND PLANNING
Dry Blending
The dry blending process constitutes the following steps
 Addition of polymer to blender and heating it at a
temperature of 80-105°C.
 The premixed and heated plasticizers are added to
blender through a spray spread over a period of 10-20
minutes.
 The stabilizer, pigments are added.
 Other compounding additives are added and the
mixture is allowed to dry up.
 The lubricants dissolved in the plasticizers are added
and the mixer is agitated thoroughly.
 The mixture is then cooled to below 60°C, screened
and transported to storage.

24. CORPORATE TRAINING AND PLANNING
Processing Considerations
 Polymer lacks thermal stability and degradation is rapid
during processing evolving hydrochloric acid. All the
metal surfaces that come in contact with the melt should be
resistant to this acid. Good ventilation of the working area
is also essential.
 Polymer doesn’t absorb water but some plasticizers may do
so.
 uPVC melts are viscous and typical flow path ratio is in the
order of 60 : 1 viscosity of plasticized PVC depends on
plasticizer level.
 Polymer is amorphous in nature so that shrinkage is low.

25. CORPORATE TRAINING AND PLANNING
Processing Techniques
Injection Moulding
Typical Injection Moulding Conditions
 Recommended melt temperatures are 180-200 °C for
uPVC and 150-190 °C for PPVC.
 Mould temperature is 20-60 °C.
 Injection pressures are in the range of 100-175 Mpa for
uPVC and 80 – 120 Mpa for PPVC.

26. CORPORATE TRAINING AND PLANNING
Extrusion
Typical Extrusion conditions are
 Temperature profile is 150-180°C for uPVC and 140-
175°C for PPVC.
 Recommended screw L/D ratio 14:1 to 17:1 for uPVC
and 17:1 to 20:1 for PPVC.
 Recommended compression ratio is 2:1

27. CORPORATE TRAINING AND PLANNING
Blow molding
- UPVC has a much lower average specific heat between
the processing temperature and room temperature than
polyethylene.
- Because of this much less heat is removed on cooling of
mouldings and hence very short cycle times are possible.
- Blow molding is confined to UPVC using general
conditions given under extrusion.

28. CORPORATE TRAINING AND PLANNING
Calendaring
 Calendaring is an important process for making UPVC film
or sheet.
 High molecular weight PVC is compounded and partly
agglomerated in an extruder mixer.
 The heated mix is then fed to an L- type calendar mixer.
The hot calendar rolls simply partly consolidate the
granules so that the resulting film or sheet is strong enough
to be drawn over a train of heated drums which are well
above the fluxing temperature of the compound.
 The PVC is therefore subjected to only a very short but
intense heating process. The resulting films with the high
mechanical properties are used for packaging applications.

29. CORPORATE TRAINING AND PLANNING
PVC Plastisol and Organosol
 Plastisol and organosol are pastes types obtained when the
voids between particles are completely filled with a plasticiser
so that the polymer particles are suspended in it.
 A typical plastisol includes paste making polymer, plasticizer,
small mount of stabilizer and filler.
 Organosols are distinguished by the presence of volatile
diluent used for reducing the paste viscosity.
 Most PVC pastes are used in the manufacture of leathercloth.
 Coating of objects are also done by pastes.
 Rotational casting , paste injection moulding processes have
been developed for making flexible products.

30. CORPORATE TRAINING AND PLANNING
Trade names
IPCL, India - Indovin
Reliance, India - Relcair
Mitsubishi gas Ind, Japan - Vinylfoil
Mitsui toatsu chemical, Japan - Vinychol
B.F. Goodrich, US - Vynaloy
Goodyear, US - Vycell
ICI - Vynide
Solvay - Benvic

31. CORPORATE TRAINING AND PLANNING
Applications of PVC
Automotive
 PVC is widely used in air filters, boat bumpers, mats,
seat belts, head and arm rests, spark plug covers, seat
covers, transmission covers.
Agriculture
 PVC is used in manufacturing of irrigation pipes and
profiles, pipe fittings, drip irrigation systems, reservoir
liners, horticultural and green house irrigation system,
sprinkler system fittings.
Building
 Floor tiles & covering, fencing, wall coverings, furniture
covers, sofa seats, house sidings, windows, doors, cabinets,
swimming pool liners, carpet backing, heat seal adhesives,
foil coatings.

32. CORPORATE TRAINING AND PLANNING
Electrical/ Electronics
 Pipe and profiles, wire extrusions, cable insulation, TV
back, cable fittings, wire sacks, electrical parts, plating
racks, tool handles.
Industrial
 PVC is used in manufacturing of film, fittings, printing
plates, screens, steel strip coatings, profiles, printing
inks, conveyor belting, battery separators, storage tanks,
gloves.
Medical
 PVC is used in medical sector to manufacture of blood
bag, glucose bag, urine bag, syringes, infusion set, tubing,
catheter tubes.

33. CORPORATE TRAINING AND PLANNING
Applications of PVC
Vinyl records PVC flexible blood bag
PVC Automobile interiors PVC wire and cable

34. CORPORATE TRAINING AND PLANNING
Applications of PVDC
- Copolymers may be used in the manufacturing of
extruded pipe and moulded fittings and in chemical plants.
- Copolymers are used in the manufacture of filament
which may be extruded from steam heated extruders with
L/D ratio 10:1 and compression ratio 5:1 into a quench
bath. These filaments are used for deck chair fabrics, car
upholstery, decorative radio grills, dolls hair, filter
brushes.
- Biaxially oriented film is used in packaging for
exceptional clarity, brilliance, toughness, and water and
gas impermeability.