Poly Styrene (PS)

Poly styrene (PS): Polystyrene is a rigid, brittle, inexpensive plastic that has been used to make plastic model kits and similar knick-knacks. It would also be the basis for one of the most popular "foamed" plastics, under the name styrene foam or Styrofoam.

Foam plastics can be synthesized in an "open cell" form, in which the foam bubbles are interconnected, as in an absorbent sponge, and "closed cell", in which all the bubbles are distinct, like tiny balloons, as in gas-filled foam insulation and flotation devices. In the late 1950s, high impact styrene was introduced, which was not brittle. It finds much current use as the substance of toy figurines and novelties..

Applications 

Automotive

Reflectors, doom lights 

Household

Soap boxes, powder boxes, bangles, toys, decorative gift articles, crystal wears, ball pen barrels, tumblers, bowls, trays, jewellery boxes, flower vases

Industrial

Geometrical applications eg. Set square scale, storage battery casing 

Electrical/ Electronics 

Tape recorder spools, audio cassettes and covers, lamp shades, battery cases, torch light cases, TV and transistor cabinets, air- conditioner front grills, CD boxes

Building

False ceiling channels and thermal insulations for building as EPS

Packaging

Rigid containers, thin walled packaging containers, disposable transparent containers, packaging of powder dairy, meat and egg products

Strengths:

1. Low cost

2. Transparent

3. High stiffness

4. Good dimensional stability

5. Good processability

6. Good electrical properties, low dielectric loss

7. Excellent resistance to gamma radiation

8. FDA compliant

9. Low moisture absorption

10. Low mould shrinkage

11. Very low thermal conductivity

Limitations:

1. Brittle at room temperature

2. Poor mechanical properties above 70°C

3. Poor chemical resistance, especially to organic solvents

4. Susceptible to UV degradation

5. Highly flammable

6. Limited resistance to organic solvents, when compared to polyolefins.

7. Possesses tendency to stress cracking

8. Low creep strength under repeated stress

PROPERTIES 

1. Hard, rigid and transparent thermoplastic

2. Low moisture absorption

3. High dimensional stability

4. High refractive index

5. Good colourability and processability 

6. Good dielectric properties

7. Low mould shrinkage

8. Very low thermal conductivity

9. Highly inflammable and burns with a luminous sooty flame

10. Limited resistance to organic solvents, when compared to polyolefins 

11. Highly brittle

12. Degraded by UV radiation

13. Possesses tendency to stress cracking

14. Low creep strength under repeated stress.