Polystyrene is a versatile plastic with good electrical properties, moldability, and transparency. It exists as a homopolymer and in copolymers like HIPS and ABS. It is manufactured through mass, solution, or suspension polymerization of styrene monomer derived from ethylbenzene. Polystyrene has applications in household goods, electronics, medical devices, packaging, and construction due to its low cost, rigidity, and resistance to water absorption. It can be processed through injection molding, extrusion, and thermoforming.

2. POLYSTYRENE
(POLY VINYL BENZENE)
SPECIFICATIONS COPOLYMERS
 Low cost
 higher weight
 good electrical properties
 good mould ability
 excellent color range
 transparency
 rigidity
 low water absorption
 High Impact Polystyrene
(HIPS)
 Styrene acrylo nitrile (SAN)
 Acrylonitrile Butadiene
Styrene (ABS)

3. MONOMER PREPARATION
benzene + ethane ethyl benzene
Ethyl benzene styrene

4. MANUFACTURING
1. Mass polymerization
• Gives polymers of high clarity/electrical resistance
• Styrene monomer is heated @ 800c for 2 days till 33%-35%
polymerization occurs
• The whole mixture is run out in to a tower about 25 feet
height
• Temp. in tower
top= 1100c middle= 1500c
bottom= 1800c (boiled off residual monomers)
• Cooled and disintegrated and packed

6. 2 . Solution polymerization
 Styrene and solvent blended together and pumped
through number of reactors
 Solvent and polymer fed in to extruder
 Extrudated , granulated and stored
 Residual monomers and very low molecular weight
polymers are removed

8. 3. Suspension polymerization
 Monomer suspended in droplets
 Use soluble initiator like BPO
 Coat the droplets using suspension agents like PVA
 Polymerization takes place, unreacted monomers removed

9. GENERAL PROPERTIES
 specific gravity - 1.05
 tensile strength - 32.4-56.5 MPa
 tensile modulus - 3103-3276 Mpa
 flexural modulus - 3103-3448 Mpa
 elongation at break - 1.2-3.6 %
 Impact strength - 13.3-24 J/m
 hardness - M 60-84
 Glass transition temp.- 74-1100c
 dielectric strength - 19.7 KV/mm

10. PROCESSING TECHNIQUES
INJECTION MOLDING
Melts are medium viscous
GPPS(general purpose PS)
wall thickness – 150:1
processing temp - 200-2500c
HIPS(high molecular weight PS)
wall thickness - 130:1
Processing temp – 180*250*c
Injection pressure - 30-275Mpa

11. EXTRUSION
 Used for making sheets used in thermoforms.
 Screw L/D ratio – 25:1 to 30:1
 Compression ratio – 2:1 to 3:1
 Processing temp – 150* - 250*c
THERMOFORMING
 Forming temp 130* - 180*c
 Removal temp 85*c

12. PROCESSING CONSIDERATIONS
• The negligible water absorption avoids the need of
pre-drying
• Specific heat of PS is less, therefore higher
plasticizing machines should be used
• Due to amorphous in nature, polymer gives low
mould shrinkage
 The strong dependence of apparent viscosity or shear
rate .this necessities particular care in the designers
complex extrusion dies

13. APPLICATIONS
HOUSEHOLD AUTOMOTIVE
 Power boxes
 Combs
 Toys
 Bangles
 Decorative gift articles
 Ball pen
 Water jug
 Mugs
 Plates
 Reflector
 Doom light
 Display signs
 Automotive penal covers

14. ELECTRICAL &ETRONICS MEDICAL
 Light diffusers
 Battery case
 Electrical coil forms
 TV and transistor cabinets
 Refrigerator
 Door and body liners
 Floppy storage boxes
 Disposable syringe

15. PACKAGING INDUSTRIAL
 Thin walled packaging
 Containers
 Bottles
 Fish packaging
 Flower packaging
 Bottle caps
 Battery case
 Filling cabinets
 Blade dispenser
CONSTRUCTION
 Toilet seats
 Wall tiles
 Towel racks
 Window envelope

16. REFERENCE
 PLASTIC MATERIALS
-CIPET
• PLASTIC MATERIALS
-BRYDSON.JA
 Working with Polystyrene
-Bill Fry