1. PLASTIC ADDITIVES BY
D.Surendra,Lecturer in chemistry, D.K.W(A),G.D.C,Nellore
VI Sem, Polymers (Cluster A)

2. Additives
Any substance that is added generally in small concentration to resins in order to:
Alter their properties
Facilitate their processing
Change the physical, chemical or electrical properties of end products.
Reduce the cost

3. Features of Plastic Additives
Effectiveness in their function
Stable under processing conditions
Economic
Compatibility with polymer Matrix-at molecular level
Neither volatile nor extrude to the surface
Neither bleed nor bloom
Must have low vapour pressure at high temperature
Non- hazardous, non-impart taste & colour

4. Types of Additives Fillers Plasticizers and softeners
Lubricants and flow promoters
Anti-aging additives
Flame-retardants
Colourants
Blowing-agents
Cross-linking agents
Photo stabilizers and Nucleating agents

6. Fillers Fillers are usually solid additives.
To give the plastic better hardness, tensile strength, finish and work ability to the product.
To reduce the combustibility and increase water resistance.

7. Classification of fillers
Perticulate rubbery resins fibrous cork
Inert & Reactive& non-reactive Laminar &
Reinforcing Random
Organic Inorganic

8. Organic fillers:
cellulosic fillers-wood floor,cotton,paper pulp etc.,
carbonaceous fillers-carbon black and graphite.
Inorganic fillers:
mineral fillers-Asbestos, powdered-mica, talc, silicate
clays etc.,
powdered metals-Iron,lead,copper and aluminium

9. Examples of fillers
Air fillers- Foam, Porous and honeycomb plastics, expended polystyrene etc.
Fillers in powder form: Phenoplasts, phenoliths and aminoplasts.
Fiber filled plastics :Phenol resins, fiber glass materials etc.
Filler in the sheet form: Hardened paper, cloth laminate,asbestos-cloth laminates and wood laminates,etc.

11. Plasticizers and softeners
Plasticizers are generally cyclic or acyclic organic chemicals that are added to synthetic plastics and results.
These are high boiling, low molecular weight, non –volatile liquids.
Reduce internal friction between polymer chains.

12. Effect of plasticizers
Easy melt
Improve flexibility
Increases softness and flexibility
Improve process ability
Alters softening point, tensile strength, elongation at break and impact.

13. Types of plasticizers
A. Cyclic plasticizers :They are used in the manufacture of synthetic plastics and resins.
Ex: Dibutyl phthalate,try cresyl phosphate,Dioctyl sebecate.
B.Acyclic plasticizers:These are less compatible and are usually employed together with plastics. Ex:Adipic acid esters,Epoxidised esters,oleic acid esters

15. Lubricants and flow promoters
To reduce friction between the material and the processing equipment(Adhessive forces)
To reduce heat and wear between two surfaces either between the polymer molecules.(cohesive forces)
Reduces thermal degradation of the polymer
Modifies flow characteristics
Homogeneous the polymer melt with other polymer additives.
To prevent the plastic from sticking to the mould surface during processing.

16. Ex: Silicone fluids, metal soaps,hydrocarbon waxes,amine waxes,ester derivatives,
Long chain esters,glyceryl monostearate,fatty acids and amides

17. Flow promoters Low molecular weight materials.
Impact better flow properties to the polymer mix under processing conditions without effecting the main properties under service conditions.
EX: Chlorinated polyethylenes, acrylate copolymers

19. Anti aging additives
The properties of the most plastic materials change with time in an adverse manner. These changes are a result of structural modifications.
Causes for structural modifications:
oxidation
Attack by ozone
Dehydro chlorination
UV attack

20. For controlling structural modifications certain anti aging additives are added to the polymer materials. These are
Anti oxidants ----peroxide decomposers
metal deactivators
UV light absorbers
Anti ozonants: Derivatives of Para phenylene diamine

21. Stabilizers against Dehydrochlorination:
Ex: Alkali earth oxides,epoxy compounds etc.
UV Absorbers:o-hydroxy benzophenones,o-hydroxy phenyl benzotriazoles and salycylates.

22. Flame Retardants Prevent combustion by - insulate
- creating endothermic cooling reaction
-coating the product
Types of Flame retardants:
1.Additive flame retardants-mineral flame retardants
2.Reactive flame retardants –organo halogen,o-phosphorous
EX: Antimony trioxides, chlorinated paraffins , bromine compounds, substances containing N, B , Si , P , Cl , Br etc.

24. Colourants Dyes (soluble in polymers)
Impart brilliant transparent colour to clear plastics
Inorganic &organic
AZOS for brightness and clarity
Pigments (insoluble in polymers)
Inorganic- Titanium dioxide(white)cadmium sulphide(yellow orange)
Organic-Bennzidese(yellow-orange),copper pthalocyanine(blue),aniline black(black).

26. Blowing agent Or Foaming agent
It is a substance which is capable of producing a cellular structure via a foaming process in materials that undergo hardening or phase transition. Types: Physical blowing agents Ex: Nitrogen and carbon dioxide, inert gas –low cost, low boiling liquids chemical blowing agents Ex: Azodicarbonamide, Azonitriles-decompose on heating and produce free radicals.

28. Cross-linking agents
Cross-linking or curing or vulcanizing agents are important and essential ingredients for the above composition in the formation of thermo set plastics and vulcanized rubber.
Processing types
Molecules which bridge two polymer molecules during cross-linking. Ex: sulphur, selenium diene rubbers
Formaldehyde Phenolics
Molecules which initiate cross-linking reaction.
Ex: peroxides poly esters

29. Molecules which purely catalytic in their reaction.
Ex: Acids-- phenolic resins,
Amines ---epoxides
.Molecules which attack the polymer chain to generate active -cite. Ex: peroxides

31. Photo stabilization
Photo stabilization is the retardation or elimination of the photodegradation of any polymer during storage, processing and performing conditions.
Stabilizers are classified as
Anti-oxidants
UV Absorbers

32. 1.Preventive anti-oxidants----to prevent generation of radicals
Anti-oxidants :protect the polymer from degradation by oxygen attack (oxidative degradation)
These are two types
1.Preventive anti-oxidants----to prevent generation of radicals
Ex: peroxide decomposers- Dilauryl thioprpianate, P-substituted phenyl phosphate
Metal deactivators------Anti ozonants, wax additives
2.Chain-breaking anti-oxidants----these are interrupt the propagation of oxidative chain degradation.
Ex: Styrenated phenols,phenyl napthylamines

33. UV Absorbers:
These interact with the bfirst step of the photo oxidation process.
Absorbs the harmful uv radiations before it reaches to the photo active chromophoric species in the polymer molecule.
Hence, energy dissputes in the manner that does not lead to photosensitization.
A uv absorber should be light stable, non-toxic and chemically inert.
Ex: Phenyl salycilate,2,4-hydroxy benzophenone etc.

36. Nucleating agents
Nucleating agents increase the rate of crystallization.
Promote the formation of more spherulites.
Enhanced properties such as flexural modulus and heat deflection temperature.
Improved moulding productivity of polymer
Increased transparency of polymer.
Ex: Sodium, potassium, lithium benzoates
Inorganic powders- clays, silica flour etc.

39. THANK YOU