Download ADDITIVES

WELCOME
ADDITIVES
• Polymers unsuitable for processing in pure
unmodified form
e.g. Polyolefins – Oxidative degradation
due to heat and pressure during
processing
PVC - Degradation at processing
temperature
ADDITIVES
Any Substance that is added
generally in small concentration to
resins in order to :
• Alter their properties
• Facilitate processing
• Change the physical, chemical or
electrical properties of end products.
• Reduce the cost
Requirements of Additives
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Effectiveness in their function
Stable under processing conditions
Stable under service 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 & odour
CLASSIFICATION
Assist Processing
• Processing Stabilizer
• Lubricants - External
• Lubricants - Internal
Modify Bulk Mechanical
Properties
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Reduce Cost
Plasticizer
Reinforcing filler
Toughening Agents
Fillers
Diluents & extenders
CLASSIFICATION
Surface Properties
Modifier
Optical Properties
Modifier
Anti-Ageing
Others
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Antistatic
Anti Slip
Anti wear
Anti block
Adhesion Promoters
Nucleating Agents
Colorants
UV Absorbers
Fungicides
Blowing Agents
Flame Retarders
Processing Stabilizers
• Prevent degradation which is caused by
– Heat
– Oxygen
• What Happens ?
– Oxygen combines with Polymer under high
temp to form carbonyl compounds which
leads to yellow & brown discolouration.
Processing Stabilizers
• Primary Stabilizers – Antioxidants
• Secondary Stabilizers – Peroxide
decomposes
• Chelating Agents – Metal deactivators
• Special Stabilizers (Heat Stabilizers) – for
halogenated polymers
Antioxidants
( Primary Stabilizer )
• They inhibit or retard the oxidative degradation
of materials at normal or elevated temperature
during processing, storage or service due to
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Heat
Light
Chemical Induction
• How it works?
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It interrupt the chain reaction by combining with
the free radicals forming a non reactive products
(Amount : 0.1 – 0.5%)
Effect of Oxidation
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Loss in Tensile Properties
Discolouration i.e. yellowing,
Increase in Brittleness
Melt Flow Instability
Change in appearance.
Hardness increases.
Loss of Gloss.
loss of transparency.
Cracking.
• Hindered Phenols or Aromatic Amines
Secondary Stabilizer – Peroxide
decomposes
• How it works?
–
Peroxides are reduced to alcohols & are
deactivated.
• EX:
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Sulphur & Phosphorus Compounds such as
Sulphides, thioethers, tertiary phosphites &
phosphorates.
Chelating Agents – Metal
Deactivators
• Prevent degradation by metal ions
(impurities in polymers – ziegler-natta
redox initiators, fillers, pigments etc.)
• EX:
– Organic Phosphines & Phosphites
– Higher Nitrogenated compounds – Melamine,
diamine etc
Heat Stabilizers
• Prevent Degradation
• Absorb & Neutralize HCl gas evolved
• Prevent Oxidation reactions
• Prevent Discolouration
• Displace active substituents with stable
substituents
Heat Stabilizers
• Lead
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Tri Basic Lead Sulphate (TBLS)
Dibasic Lead Sulphate (DBLS)
Basic Lead Carbonate
Dibasic Lead Phosphite
• Organo-tin
– Dibutyltin meleates
– Dibutyltin bis mercaptides
• Cadmium / Barium /Zinc
– Cadmium/Barium laurates
– Cadmium/Barium/Zinc Complexes
Synergistic Stabilizer Systems
• The term Synergism is used to describe
the combined effect of two or more
stabilizers, which is greater than the sum
of the effects of the individual stabilizers
used in isolation.
Effect (A+B) > Effect A + Effect B
Lubricants or Flow Promoters
Functions :• To reduce friction between the material and the
processing equipment. ( Adhesive forces)
• To reduce heat & wear between two surfaces
either between the polymer molecules
( Cohesive forces) or between the polymeric
material and the equipment.
• Reduces thermal degradation of the polymer.
• Modifies flow characteristics.
• Homogenous the polymer melt with other polymer
additives.
• To prevent the plastic from sticking to the mould
surface during processing
Lubricants or Flow Promoters
• External Lubricants
• Internal Lubricants
External Lubricants
• Prevent friction between polymer melt & metal
surface
• Prevent sticking to the metal parts
• They are usually high molecular compounds and
have non-polar groups.
• They have low compatibility with the polymer but
have high affinity for the metal surface.
• During processing they form a thin film between
polymer melt & metal surface.
• They improve surface finish & gloss.
• They help to reduce melt viscosity and give a high
output rate.
External Lubricants
• Metal Soaps
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Metal Stearates
Zinc Stearates
Calcium Stearates
Magnesium Stearates
• Hydrocarbon waxes
• Stearic Acid & its calcium, lead, Ba, Cd Salt,
Hydro carbon & Esters
Internal Lubricants
• Promotes Flow by reducing cohesive forces
between molecular interfaces within the resin
• They are usually low molecular weight
compounds, having polar groups.
• They function by reducing intra-molecular friction
before and during the melt formation of the
polymer by promoting flow and reducing melt
viscosity of the polymeric mass.
• They also enhance polymer properties like heat
stability, impact strength, colour & clarity.
Internal Lubricants
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Amine Waxes
Ester Derivatives
Glyceryl mono stearate
Long chain esters
Fatty Acids & Amides
Ethylene bi stear amide
Zinc Stearates
Selection of Lubricants
• Metal Soaps – Low Compatibility with
polymer, so used as external lubricants
• Long Chain Fatty Acids – Used as Internal
Lubricants for polar polymers.
• Long Chain di-alkyl esters – Medium
compatibility, so act as external & internal
lubricants.
• High Molecular weight paraffin wax – low
compatibility with polar polymer, so used
as external lubricants.
Plasticizers or softeners
• Improve process ability by reducing Tg
• These are high boiling non-volatile
solvents
• Polar with a high Mol. Wt. ester type
organic compounds.
• Reduce internal friction between
polymer chain.
Effect of Plasticizers
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Easy melt
Improve flexibility
Increase Softness and Flexibility.
Improve Process ability.
Alters Softening point, Tensile Strength,
Elongation at break & Impact.
Types of Plasticizers
• Primary – These are highly compatible
with PVC and can be used alone.
• e.g.
– Phthalates – Di-Octyl Phthalate (DOP), Di Iso
Octyl Phthalate (DIOP)
– Phosphates – Tricresyl Phosphate (TCP),
– Sebacates,
– Adipates.
Types of Plasticizers
• Secondary – These are less compatible
with resin & and are usually employed
together with primary plasticizers.
• e.g.
– Di Octyl Sebacate (DOS)
– Adipic Acid Polyesters
– Epoxidised oil.
Extenders
• These are not used alone as plasticizers.
• They are limited compatibility with polymer.
• In conjunction with true plasticizers it enhance
the efficiency of plasticizers.
• Low Cost.
• It replaces the plasticizers without any adverse
effect on polymer.
e.g.
– Chlorinated paraffin wax,
– oil extracts.
Selection of Plasticizers
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Solvating power
Efficiency
Compatibility
Flame retardant
Toxicity
Low Temp. Performance
Cost
FILLERS
It is used to modify mechanical
properties & to reduce the cost.
Effect of Fillers
• The use of inert fillers can influence the
polymer properties in the following ways :– Increase in density.
– Increase in modulus of elasticity.
– Lower shrinkage.
– Increase in hardness.
– Increase in HDT.
– Reduction of raw material cost.
– For e.g. Calcium Carbonate,Red mud
Fillers
Purpose
Filler
Bulk
Wood Flour
Saw dust
Wood pulp
Sisal / jute
Purified cellulose
Mica / Rock
Fillers
Purpose
Filler
Hardeners
Inorganic Pigments
Mineral Powders
Metallic Oxides
Powder Metals
Graphite
Fillers
Purpose
Filler
Chemical Resistance
Glass Fibres & Fabrics
Synthetic Fibres & Fabrics
Graphite
Metallic Oxides
Asbestos
Ceramic Oxides
Silica
Thermal Insulation
Fillers
Purpose
Filler
Appearance
Colour Pigments
Dyestuffs
Carbon Flakes
Powder Metals
Phosphorescent Minerals
Woven Fabrics
Fillers
Purpose
Filler
Reinforcement
Glass fibres
Asbestos Fibbers
Cellulose Fibbers
Cotton Fibbers
Papers
Synthetic Fibbers
Fibrous Fillers & Reinforcement
Reinforcing fillers are those which enhance
the mechanical properties like :
• Tensile Strength
• Modulus
• Hardness of a polymer compound.
The product become stiffer and stronger
than the base polymer.
Fibrous Fillers & Reinforcement
Glass Fibres –
Increase (Tensile, Compressive,Flexural )
Strength ,Increase rigidity, creep resistance
hardness and decrease thermal expansion
co-efficient, elongation at break.
Minerals such as talc, calcuim carbonate,
mica – increases the compound rigidity,
improve the temperature resistance and
reduces shrinkage & warpage.
Coupling Agents
These are used to increase the adhesion
between polymer & filler, fiber by covalent
bonds.
Ex: Methacrylato-chromo chloride used for
glass fibres & Polyester resin
Organosilanes are used for PVC , ABS and
PA
Antistatic Agents
• Static charge may built up simply by friction
with the ambient air
• Most plastics have low surface conductivity
• Static charge is not discharged fast enough
Troublesome effects like:
• Heavy contamination of plastics parts
• Shock as charge flows ( floor covering ,
door handles)
Antistatic Agents
• Chemicals added to plastics to reduce built
up of electrostatic charges on the surface of
materials
Accumulations can occur during processing
and at various handling points
• Static charges are dissipated by increasing
the surface conductivity
Antistatic Agents
• Prevent electrostatic charges – mostly seen in
PE, PP, PS, Nylons, Polyesters, Urathenes,
Cellulosics, Acrylics & Acrylonitriles
• Because of insulation properties electrical
charge may get deposited on the surface of
the plastics produced during processing.
• This may cause severe damage to the
products & equipments.
• It may cause accumulation of dust.
• The accumulation of static charge can be
minimized by the use of antistatic agents.
Antistatic Agents
• EX:
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Amines
Quaternary ammonium compounds,
Phosphates,
Esters,
Polyethylene glycol esters
Slip & Anti block Agents
• Slip : Reduces coefficient of friction- They
are high molecular weight fatty alcohols
• Amount (0.05 – 0.2% )
e.g. For film of 25 micron 0.01% of
Oleamide
Slip & Anti block Agents
• Anti block Agents : Prevent adhesion
between the film surface
Amount (0.05 – 0.2%)
e.g.
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Calcium Carbonate in PVC film
Metal Salts
Fatty Acids
Natural & Synthetic Waxy Materials
Selection of Slip & Anti block Agents
• Must not spoil optical properties.
• Must not interface with the adhesion ink to
film.
• Must not prevent the sealing of film.
• Must be colour less
• Must be odour less
• Must be non toxic
Nucleating Agents
• Aiding transmission of white light in Plastics
• Forms large nos. of nuclei & reduces the
size of spherulites.
e.g.
– Sodium, Potassium, Lithium benzoates.
– Inorganic Powders – Clays, Silica Flour
Optical Brighteners
• It makes a mask over the yellowness formed
during processing.
• Optical Brighteners are organic substance
which absorb UV radation
e.g.
– Benzosulphonic & Sulphonamides
derivatives.
– Vinylene bisbenzoxazoles.
– 4-alkyl-7-dialkyl amino coumarins.
Colorants
• Produces varieties of coloured
polymers
• Also improves
– Mechanical Strength
– Specific Gravity
– Clarity
Colorants
Dyes (Soluble in Polymers)
»Impart brilliant transparent colour to
clear plastics
»Inorganic & Organic
» AZOS (,180 – 2000C) for brightness and
clarity
»Anthraquinone (AQ) –Good heat
transparent weathearibility
(Auto tube light)
Colorants
• Pigments (In-Soluble in Polymers)
– Inorganic
– Organic
Colorants
Inorganic Pigments :
• Titanium dioxide - White
• Cadmium sulphide - Yellow orange
• Lead chromate - Yellow orange
• Chromium oxide - Green
Organic Pigments :
• Benzidese – Yellow orange
• Copper phthalocyanine -Blue
• Chlorinated copper phthalocyanine
• Aniline black - BLack
Selection of Colorants
• Heat Stability
• Disperse ability
• Light fastness
• Chemical Inertness
• Opacity or transparency
Anti-Ageing Additives
• Deterioration by Atmospheric
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Radiation
Temperature
Oxygen
Water
Micro-Oranisms
Gases etc
Ultraviolet Light Absorbers
• Detected by
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Loss in Tensile Properties
Discolouration
Brittleness
• EX:
– Black in any form : Carbon Black, Black dye,
Black paints
– Benzophenones – for PE, Polyesters
– Benzotriazoles – for PS, Polyesters
Impact Modifier
• To enhance the impact properties of
certain brittle polymers so as to use in the
field.
e.g.
– Chlorinated polyethylene ,EVA are used for
PVC.
– SBR is used for polystyrene material.
– EPDM is used for PP ( Bumpers)
– Acrylic rubbers for Poyamides
Flame Retardants
• Plastics + Fire –free radical formation
combines with Oxygen – CO – CO2
• Application : Automobile, Aerospace,
Electrical,Transportation,Building,Furnit
ure, TV cabinet
Flame Retardants
• Prevent Combustion by
– Insulate
– Creating endothermic cooling reaction
– Coating the product
• EX: - Aluminium trihydrate ( Nylon)
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Antimony trioxides (ABS)
Chlorinated Paraffin
Zinc borate
Halogen Compounds
Phosphorous acid esters ( PA,POM,FRP)
Nitrogen Compounds
Blowing Agents
• Blowing agents are also known as
foaming agents. Upon heating liberate
Gas
• Are used to produce porous polymers
i.e. cellular/foam plastics.
Blowing Agents
Physical Blowing agents: Nitrogen & CO2
inert gas- Low cost, No solid residue
Trichlorofluromethane – PU foam
Pentane and Heptane - PS foam
Chemical Blowing agents: High temp, Azo
Dicarbonamide decompose on heating to
produe free radicals and N2 gas
Blowing Agents
• Blowing agents are also known as foaming
agents. Upon heating liberate Gas
• Are used to produce porous polymers i.e.
cellular/foam plastics.
• EX:
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Ammonium bi carbonates
Sodium bi carbonates
Azo Di carbonamide
Azo bis formamide
N-nitrogen Compound
Sulfonyl Hydrazides
Master Batches,Additives & Reinforced Compounds
Material
Master Batches
Master Batches &
Reinforced
Compounds
Polymer additives
Supplier
S.C.J. plastics Ltd. New
Delhi
www.scjindia.com
Aalekh Polymers (P)
Ltd.
8/30, Kirti Nagar New
Delhi =15
Ph. No. 25195193
Fine organics Bombay
022-25116900-02
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