polycarbonate

1. POLYCARBONAT
E
Presented by:-
Himanshu Kr. Bhatt
1508003

2. Introduction
• Polycarbonates (PC) are a group
of thermoplastic polymers containing carbonate
groups in their chemical structures.
• Polycarbonate, an amorphous thermoplastic, is
considered to be a well proven technical plastic.
• PC used in engineering are strong, tough material, and
some grades are optically transparent.(Lexan* 9030)
• Alternative titles :Lexan, Merlon, ZELUX ,PC

3. History
 In 1953, polycarbonate was discovered
independently by Dr. H. Schnell of Bayer AG,
Germany and by D. W. Fox of General Electric
Company, USA. It has been used in commercial
applications since the late 50's.
 Polycarbonate was initially used for electrical and
electronic applications.
 polycarbonate’s outstanding combination of
beneficial characteristics made it the material of
choice for many other applications like CD/DVD, all
type of data storage device, water bottles , car head
lamps and many more.

4. Structure
 A polycarbonate molecule is composed by a
Bisphenol A part and a carbonate group.

5. Structure cont.
 Bisphenol A contains two aromatic rings, which are
responsible for PC’s stiff backbone.
 The Bisphenol A group also contributes to PC’s
inability to crystallize. This amorphous structure gives
the polymer its particular transparency.
 The Characteristic high glass transition temperature
(Tg = 145ºC) of PC is caused by the minimal
molecular rotation about the bonds .

6. Synthesis
 Polycarbonate is synthesis by two ways :
1- Transesterification (or ester exchange)
2- Phosgene method

7. Transesterification
 Transesterification is the process of exchanging the
organic group R″ of an ester with the organic group
R′ of an alcohol. These reactions are
often catalyzed by the addition of
an acid or base catalyst .
Alcohol + ester diff. alcohol + diff. ester

8. Cont.
In the transesterification mechanism, the carbonyl
carbon of the starting ester (RCOOR1) undergoes
nucleophilic attack by the incoming alkoxide (R2O−) to
give a tetrahedral intermediate, which either reverts to
the starting material, or proceeds to the transesterified
product (RCOOR2).

9. Cont..
 Here in case of polycarbonate the reaction takes
place between Bisphenol-A (alcohol)and
diphenylcarbonate (ester) gives a polycarbonate
as follows:-

10. +
Bisphenol-A diphenylcarbonate
carbonateBisphenol-A
POLYCARBONATE
NaOH

11. Mechanism

12. 2 +
+
-

13. +

14. Phosgene method
 The main polycarbonate material is produced
by the reaction of bisphenol A (BPA)
and phosgene COCl2
 The overall reaction can be written as follows:

16. Mechanism

21. Advantage and Disadvantage
Transesterification
 Advantages
• Solvent Free
• Potentially Phosgene
Free
 Disadvantages
• Intermediate Molecular
Weight
Phosgen
 Advantages
• High Molecular Weight
• Excellent Optical Clarity
and color
 Disadvantages
• Phosgene based
• Uses H2O and CH2Cl2

22. Processing

23. Process description
 BPA and DPC are fed into the preparation tank
where they are thoroughly molten.
 In order to achieve the high-purity monomer
required for the production of high-quality
polycarbonate suitable purification steps such as
distillation, filtration and melt crystallization are
considered.

24.  The pre-heated raw materials are fed in liquid form in
a defined molar ratio into the transesterification
reactor where they are mixed with catalysts and
heated up to the desired transesterification
temperature.
 During the formation of polymer chains phenol
begins to split-off.
 After the transesterification has been finished the
short polymer chains, the so-called oligomers, are
discharged and fed into the prepolycondensation I
reactor for the next reaction step

25.  Using higher temperatures and a lower vacuum,
molecules of mid-size chain length are built-up.
 The product is then transferred to the
prepolycondensation II reactor for further chain
growth and subsequently to the final
polycondensation reactor.

26.  The final polycondensation reactor is used to
achieve the desired polymer chain length and
hence the desired properties of the Polycarbonate
 Both the prepolycondensation II stage and final
reactor are equipped with a horizontal disc-ring
agitators that provide a high surface area to
ensure easy mass transfer and chemical reaction.

28. Manufacturing
 Extrusion
The molten PC is passed
through a die that gives
the material its final
shape. After this, the melt
is cooled rapidly. Long
pipes and sheets are
created by this process
 Molding
The PC melt is pressed into
a mold with the defined
shape of the final product.
The melt is then cooled
inside the mold. This
process is ideal for specific
parts such as automotive
and computer parts

29. Characteristics of PC
 High mechanical stability
 Good thermal stability
 Excellent impact toughness
 Good weathering stability
 High light transparency (panels are transparent)

30. Cont.…
 High dimensional stability
 Low moisture absorbtion
 Good dielectric properties
 Self-extinguishing
 Good resistance to high energy radiation

31. Physical and Mechanical
Properties
 Good tensile strength without excessively high rigidity.
 Exceptionally good impact resistance.
 The stress-strain behavior of PC is characterized by a
wide creep range between the yield point and fracture
 The sear module is temperature dependent and shows
rapid reductions in rigidity above +120ºC.

32.  Due to their high impact resistance, PC panels
are some of the most shatter-proof glazing
materials.
 Uncrystallized polycarbonate has excellent
transparency and have high refractive index of
about 1.584.
 The relative rigidity of the chain causes high
viscosity in the liquid state.
 Non- toxic in nature and easily coloured.
 Highly recyclable and cost effective.

33.  Benzene rings restrict the flexibility of the molecule.
 Due to bisphenol-A it Is amorphous in nature.
 Due to rigid backbone Tg =145 °C and Tm =
225-250 °C
 Excellent resistance to shock even when cold.

34. Chemical Properties
 Resistance to dilute mineral acid but poor resistance to
aromatic, alkali, chlorinated hydrocarbons.
Dilute Acid (good)
Alcohols (good)
Aliphatic Hydrocarbons (good)
Oils and Greases (moderate)
Dilute Alkalis (poor)
Aromatic Hydrocarbons (poor)
Halogenated Hydrocarbons (poor)

35.  PC absorbs only small quantities of water (<0.6%)
and its mechanical properties are not affected by it.
 PC can be used for making objects frequently
washed with hot or sterilized water, but a long
period of time in hot water (0 > 60°C) causes a
decomposition resulting in a drop in shock
resistance.
 PC is fairly stable in the presence of ozone.
Stability in UV light is not exceptional and PCs turn
yellow fairly quickly.
 Certain grades are approved for medical use.

36. Thermal properties
 PC has good heat and cold stability.
 Above the glass transition point of +140ºC
however, PC starts to soften rapidly.
 PC is practically self-extinguishable i.e.,
resistant to fire.

37. Dimensional properties
 Polycarbonate, as other amorphous polymer ,
offer limited retraction when molded(>0.6%)
 Its low absorption of humidity gives it good
dimensional stability in a humid atmosphere.
 PC has good creep resistance, especially
when reinforced with fiber glass.

38. Electrical properties:
 Polycarbonate has good insulating properties
little affected by variations in temperature
or humidity.
 Dielectric constant is higher than PTFE and
polyolefin

39. Application
 Electrical and Electronics components:-
due to good insulating and high dielectric
strength pc is used for making of-
Protective case for mobile
phones

40. Switch board
Film capacitors
Electric charger
LED

41. TRANSPARENT
ENCLOSURES

42. Construction materials
PC’s outstanding strength makes it suitable for
bullet-resistant or shatter-resistant glass
application.
PC wall for sound
insulation

43. STRUCTURAL GLAZING

44. Data storage
Compact disk Digital versatile disc

45. Medical application
 Filters housing, tube connectors, surgical
staples
(due to strength, purity, transparency,
ability to stand all sterilization(steam,
gamma-rays etc..) ) which shows its bio-
inertness

46. General application.
 Due to its low weight and high
impact resistance, polycarbonate
is the dominant material for
making automotive headlamp
lenses.
 The cockpit canopy of jet fighter
is made from a piece of high
optical quality polycarbonate.

47.  Passenger cars fleet of train is
made of polycarbonate.
 PC’s relatively low weight in
comparison to other high
strength materials and its high
ductility make it attractive to be
used in lenses and windows

48. Polycarbonate Blends
Polycarbonate is blended with other polymers to
enhance its properties. Some of which are :-
1. PC/ABS blend
In a compounded blend of Polycarbonate and ABS.
The PC contributes impact and heat distortion
resistance, while the ABS contributes processability
and chemical stress resistance, and cost reduction
below PC.

49. Properties of PC/ABS
 Impact resistance between ABS and PC
 Strength and stiffness between pc and abs
 Heat resistance superior to ABS, less than PC
 Flame retardant system more stable in processing
than ABS

50. uses
 Portable appliances,
flashlights, phones
 Laptop computer cases
 Keyboards, monitors,
printer enclosures

51.  automotive instrument panel
retainers
 wheel covers
 small tractor hoods
 non-professional safety
helmets

52. PC/PBT(polybutylene terephthalate)
 In a compounded blend of Polycarbonate and
PBT. The PC contributes impact, stiffness and
heat resistance, while the PBT contributes
chemical resistance. The usual moisture
sensitivity of the crystalline PBT is overcome by
the PC in the blend.

53. Properties of PC/PBT
 impact resistance
 low temperature impact resistance, ductility
 heat resistance
 chemical resistance

54. What is made with PC/PBT
 Automotive bumpers
 Automotive side
moldings
 Lawn and garden tractor
hoods

55.  Hand tool housings
 Irrigation components
 Wire connectors

56. How do these properties
compare to other materials?
 One of the biggest advantages of
polycarbonate is its impact strength. The
following diagram compares the impact
strength of polycarbonate to other commonly
sold plastics.

57.  Polycarbonate does have its disadvantages. It has
only fair chemical resistance and is attacked by
many organic solvents.
 It is also fairly expensive compared to other plastics.
It has been as much as double the price of ABS.
 In applications where lower heat and impact are
needed, ABS can be quite a bargain compared to
polycarbonate.

58. How is polycarbonate sold?
 In general, the primary distinguishing
characteristic of a grade of polycarbonate is
its melt flow.
 The only exceptions are glass fiber reinforced
grades, which are sold based on the
percentage of glass fiber used in the
production of the plastic.

59.  There are two major types of polycarbonate sold.
1. Virgin polycarbonate is polycarbonate which has
not been altered from the time of original
manufacturing to the purchase of the product.
2. Polycarbonate regrind comes from polycarbonate
that is taken from an end-user and ground into
pellets

60. Thank you for
your Attention!