2. What are
additives ?
Materials dispersed polymer
matrix without affecting
significantly the molecular structure
of the polymer to attend certain
desirable properties
3. Why to use additives in
plastics ?
• Improve processing conditions
• Increase resin’s stability to oxidation
• Obtain better impact resistance
• Increase or decrease hardness
• Control surface tension
• Facilitate extrusion moulding
• Control blocking
• Reduce cost
• Increase flame resistance.
5. What are fillers?
• Mostly needed by thermosets,
sometimes also needed by
thermoplastics.
• Added to reduce cost.
6. Classification of fillers
• Mineral fillers : e.g. CaCO3 , kaolin, feldspar, talc etc.
• Metallic, conductive & magnetic fillers : iron, copper,
zinc & lead
• Fire retarding fillers : Sb2O3
• Organic and special purpose fillers : carbon black, wood
flour, walnut flour
• Flake reinforcement : mica
• Continuous filament reinforcement : fibre glass,
carbon graphite filaments etc.
• Short fibre reinforcement : asbestos
7. Heat stabilizers
• To prevent degradation that occur during high
temp processing/fabrication.
• PVC largest consumer.
• e.g.- family of lead salts, complex barium cadmium
solids, non toxic Ca & Zn salts
8. • Type: Ba / Cd - Clear calendered products, Injection
moulded flexible products, blown film
• Type: Ba / Cd / Zn – Clear calendered products, blown film,
flexible products, plastisol processing
• Type: Ba / Zn – Flexible calendered products, unsupported
films for garments, artificial leather for automotive
• Type: Ca / Zn (Non-Toxic) – Children’s toys, packaging films,
base coat for artificial leather, top coat for floor
coverings, conveyor belts, sealing compounds
• Type: Ba / Cd / Pb – Calendered, injection moulded
products, extreme high temp, and application.
• Type: Lead Complex – Rigid PVC pipes, casing capping,
electric wires.
9. UV STABILIZERS
• UV light 280-400nm polymers unstable
• To overcome this UV stabilizers are used.
Classification-:
1)UV absorbers: Hydroxy benzophenones
2)UV quenchers: Piperidines
3)Pigment: carbon black
Applications -:
1) carpenting outdoor/seatings
2) Acrylic coating used on outdoor sign boards
3) Light diffusers
4) Used in outer liners of HMHDPE
10. Antioxidants-:
• Polymers when subjected to oxygen attack & if
1)there exists high concentration of unsaturated c-c bonds
2)residual polymerisation catalyst
3)it is subjected to highly oxidising conditions,then it undergo
oxidation.
-to overcome this problems long service life, antioxidants
are used.
Classification -:
1)primary: hindered phenolics acryl amines
2)secondary: phosphurous &
sulphur containing compounds
11. Colorants
Colorants
Pigments (forms dispersion)
Dyes (completely soluble)
properties :
1) hiding power
2) particle distribution
3) fastness to light,heat,chem.
e.g. Benzidine yellow, red 2B pigments,
Alumina hydrate, iron oxide .
Applications:
Packaging, domestic articles, space research ,
m/c switches, transportation
12. Antistatic agent
• Due to low surface conductivity have poor
conductivity accumulation of static charge.
Which is undesirable because
1) attracts dust particles wear & abrasion &
unsightly look.
2) charged metals results into powdering.
3) it can generate spark, which can become
hazardous.
e.g. butyl stearate, tri -ethanol-amine
13. Fire retardants
• Polymers being organic compounds burn or
decompose on exposure to fire, generates toxic
fumes, smoke.
• Two techniques: 1)use fire retardant raw material.
2)use fire retardant additives.
e.g. inorganic :zinc borate
halogenated :chlorinate paraffins
applicable to polymers to be used in mines,
automobiles, air vehicles, railways, etc.
consumed by - polyesters, polycarbon
polyurethanes.
14. Cross-linking agents
• Thermosets cure either on application of heat or cross
linking/curing/ hardening agents.
• In some cases agent triggers off the reaction & therefore
linking the resin molecules or
• It enters into the parts between molecules and completes
the chain.
Classification :
1)free radical intiator : Isobutyl nitrile, Alkyl peroxide .
2)non free radical agents : Isocynate with polyol
Used : Manufacture of Thermosets like polyurethane,
Urea Formaldehyde, etc
15. Blowing agent
• Polymeric foams preparation(2 ways)
1) mechanical
2) chemically
• substances called blowing agents, which on heating
decompose giving N & CO2
• Rigid PVC,ABS,Polystyrene, polyolefins being chief
consumers.
Applications:
mattresses, pillows, insulation, foam pipes
for non-p conditions.
e.g.para toluene sulphonyl hydrazide.
16. Lubricants
• Hot processing of polymers need lubricants either internally
or externally.
• Internal lubricants decreasing normal cohesive forces
between polymer moleculesgood flow conditions by
lowering viscosity.
• External lubricant don’t let melt to stick to hot surface of
processing. By forming a thin layer at melt-solid interface.
e.g. butyl stearate, octyl stearate, stearic acid
17.
18. Impact modifiers
• To upgrade physical properties of polymer to the extent
prescribed by consumer, the additives added to polymers
are called as strength (impact) modifiers.
• They impart breakage resistance, rigidity, ease of post
fabrication, strength to sheets
• The strength imparted depends on time & temp conditions
of processing .
• Rigid PVC for prolonged outdoor exposure needs I.m.,
similarly epoxy & polyester thermosets require impact
modifiers.
