1. Iqra abdul rashid Polymer Engineering department

2. Polymer Science & Engineering TM-2052 Lecture # 03

3. 0utline Additives Plasticizer Fillers and reinforcements
Thermal stabilizers
Flame retardants
Processing additives
Curing agents
colorants

4. Additives
Additives are used for thermoplastics, thermosets and elastomers
Additives include
Plasticizers
Thermal and light stabilizers
Flame retardant agents
Fillers
Colorants
Processing aids
Impact modifiers

5. Additives Largely used additives are fillers and plasticizers
These are mixed with the polymer before processing by a variety of techniques such as
Dry blending
Extrusion
Compounding

6. Plasticizers
Plasticizers are used to reduce the modulus of a polymer at the use temperature by lowering its Tg
By increasing the concentration of the plasticizer causes the transition from the high modulus (glassy) plateau region to the low-modulus (rubbery) plateau region to occur at progressively lower temperatures
Plasticizers are low molecular weight organic compounds having a Tg in the vicinity of -500C

7. Fillers These are inert materials for thermoplastics and thermosets
They reduce the cost and improve the process ability or dissipate heat in exothermic thermosetting reactions
Fillers are used to improve the mechanical properties such as modulus, tensile or tear strength, abrasion resistance and fatigue strength
Fibers in the form of continuous strands, woven fabrics, and chopped fibers are used to reinforce thermoplastics and thermosets

8. Fillers
Fiber content of a polymer composite range from 20% to 80% of total weight

9. Fillers Two broad classifications Black fillers Non-black fillers
Carbon black
Non-black fillers
Calcium carbonate
Silica
Kaolin clay
Talc
Precipitated silicates
Mica
Sand

10. Fillers
Effect of filler depends on

11. Fillers

12. Fillers
Particle surface area
Particle size
Surface area

13. Thermal stabilizers
Used to protect a polymer against the effects of temperature and oxygen during processing
Typically low molecular weight compounds such as hindered phenols and aromatic amines
Having high diffusivity in the polymer melt and serve as free radical scavengers
Polymers will absorb UV radiation in the wavelength from 290 to 400 nm

14. Thermal stabilizers
Carbon black is widely used in tire manufacture provides good absorption in the UV range and serving as a low cost filler
Transparent thermoplastics like polycarbinate can be protected against yellowing by adding compounds like benzophenone derivatives

15. Additives Flame retardants Processing additives Curing agents
Internal lubricants
External lubricants
Curing agents
Colorants

16. Typical green passenger car tire tread formulation
Ingredients
phr
Styrene-butadiene rubber (SBR) 75
Polybutadiene (BR) 25
Silica 80
Coupling agent (liquid)
6.4
Elemental sulphur 2
N-tert-butyl-2- benzothiazole sulfenamide(TBBS)
Diphenylguanidine (DPG)
Zinc oxide (ZnO) 3
Stearic acid
Aromatic oil 34
Antidegradant (Santoflex-13)
Wax