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SURFACE PROPERTY MODIFIERS

Additives which increase as Surface Roughness

Anti Blocking & Anti Slip Additives

Block: Ability of a layer of film to adhere to another layer of film

Slip: Ability of a layer of film to slide past another layer of film

Surface roughness reduces the intimacy of contact

By incorporation of incompatible microscopic particles causing microfractures

By incorporation of rubber particles Differential shrinkage

Excessive use of anti blocking additive adversely affects optical properties

Excessive use of anti slip additive causes wet blocking

Diatomaceous earth, Silica flour, Zeolites, Fatty Acid Amides, Waxes,Boron Nitride

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SURFACE PROPERTY MODIFIERS

Additives which form Boundary layer

By exudation of the additiveSolid Lubricants: Reduces friction & wear

Molybdenumdisulfide, Graphite, PTFE Powder

Antistatic Agents:

Static charge develops on the surface when two surfaces are separated

Static charge build up depends on rate of generation & rate of decay

Static Charge build up poses lot of problems

Dissipated by:

Grounding

Increasing moisture content

External Antistatic agents By solution application Susceptible to removal

Internal Antistatic agents Exude Forms conductive layer

Ionic materials Quaternary Ammonium Compounds

Hydrophilic Materials Polyglycols, Polyhydric Alcohols, Sulfonic,Phosphoric

acid derivatives

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SURFACE PROPERTY MODIFIERS

Additives which alter Surface Polarity

Adhesion Promoters:Adhesion depends on the type of chemical bonds at interface of

polymer & substrate

Surface tension between Polymer & Substrate should be low for good

wetting characteristics

Substrate Polar Polymer Non Polar Additive Compatible polar low m.w.

Monomolecular layer Dosage & Compatibility

Phosphorous Compounds By Chelation with metal ions Acids Stearic, Salicylic, p-chlorophenylsubstituted fatty acids

Amines Piperidines Coupling Agents ( R-O-)a-M-(R-X )4-a(Tetravalent M = Silicon,Titanium,Zirconium)

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OPTICAL PROPERTIES MODIFIER

Polymer response to visible light (400-700 nm)

Ability to transmit, absorb, reflect incident light

% Transmission = [1 (R.I. 1)2/ ( R.I.2 + 1)] X 100Transmission also depends on Light Scatter

Light Scatter depends on surface irregularities & scattering centers

(particles & voids)Particle size ~ /2 Scatter maximumParticle size

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OPTICAL PROPERTIES MODIFIER

Colorants

Surface coating or dyeing, Introducing Chromophores, Mass ColorationDyes: Soluble Bleeding, Migration, Reactive, Poor light fastness, Lack of

heat stability

Pigments: Insoluble, Heat Stability, Light Fastness, Dispersability,

Chemically inert

Pigment Dispersion Lack of dust, handling ease

Optimum particle size for color value, tinting strength, transparency,

opacity characteristics

Inorganic : Unreactive Stable TiO2, Metal Oxides, Metallic Salts

Elemental : Carbon BlackOrganic: Based on chemical structure Bright

Phthalocyanines :Stability to light, heat, Chemical agents

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OPTICAL PROPERTIES MODIFIER

Fluorescent Pigments: Fluorescent dyes incorporated into thermoset resinmatrix, cured, ground

Absorb in U.V. or Visible light & reemit at other visual wavelengths.

U.V. absorption of additives inhibit the efficiency

Brighter color reflected than incident light

Luminescent & Phosphorescent Pigments: ZnS, CdS & ZnO Crystals

Store U.V. or Visible light & reemit visible light of weak intensity for short

duration when all light sources removed. Fragile, liable to fractureOptical Brighteners:

Absorb in near U.V. ~ 350-380nm & reemit in the blue end of visible spectrum~ 430-450nm

High degree of purity & Excellent dispersion essential prerequisites

Light reflected by an objectDiffuse Reflectance at (DR) = -----------------------------------------------------Light reflected by an ideal white surface

MgO reflects light radiation almost completely

DR of PS WITH 0.5% TiO2 decreases from longer to shorter wavelengths

DR of Optical Brighteners in shorter wavelength region exceeds DR of MgO

Additives capable of U.V. absorption has an adverse effect

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OPTICAL PROPERTIES MODIFIER

Benzosulphonic & Sulphonamides der ivat ives of 4-naptho ltr iazolyl st i lbene

Vinylene b isbenzoxazoles 4-alkyl-7-dialkyl am ino coumarins

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OPTICAL PROPERTIES MODIFIER

Additives altering light transmission characteristicsAmorphous Polymers Good light transmission

Crystalline Polymers Internal haze Differences in R.I. between

crystalline & Amorphous phase

Spherulites > Internal Scatter

Reduce crystallinity

Polymorphic Maximise crystals of lowest density

Reduce the size of spherulites to < by nucleationNucleating AgentsK,Na,Li Benzoates

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FLAME RETARDANTS

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FLAME RETARDANTS

Reactives: Special intermediates (Highly Halogenated or Phosphorous

Compounds) incorporated into polymer structure during crosslinkingEpoxy, Polyesters, Polyurethanes

Free from leaching, migration, volatilization Expensive

Additives: Flexible, Less expensive

Fire Retardants function by one or more of four mechanisms

1)Chemically interfere with free radical oxidation process reducing rate of

formation of highly reactive OHHalogen Compounds with Sb2O3

I>Br>Cl>F Aliphatic > Alicyclic . Aromatic

R-X R + X+ RH HX + R + OH H2O + XRCl + Sb2O3 SbOCl(s) (245-280) Sb4O5Cl2 (s)+ SbCl3(g) 410-475Sb3O4Cl2(s) + SbCl3(g) 475565 Sb2O3(s) + SbCl3(g) 658 Sb2O3(l)Halogen transports highly active Sb trap to gas phase

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FLAME RETARDANTS

Phosphorous CompoundsSynergy with Halogen compounds

O O

(RO)2P-OR + HX (RO)2P-OH +RX

Halides function in gas phase

Acidic derivatives of Phosphorous in the condensed phase

Metal cations have an antagonistic effect stable metal phosphates

Sb2O3 converted to non volatile SbPO4

Phosphoric Acid promoteschar formation

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FLAME RETARDANTS

2) Produce large volumes of incombustible gases diluting oxygen supply

Lower rate of combustion Drop in temperature < Ignition temperatureWater, Ammonia, Nitrogen, Sulfur dioxide, Hydrogen halides

(NH4)2SO4 Al(OH)3

3)React, Decompose, Change state endothermically

Absorb heat Drop in temperature , Ignition Selfextinction

4)Forming an impervious fire resistant coating cut of oxygen supply

Intumescent Thermal Insulation Reduction of volatiles

Zinc, Calcium Borate Hygroscopic

High molecular weight Organoborates

Poly alcohol + Blowing Agent + Dehydrating Agent

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FLAME RETARDANTS

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FLAME RETARDANTS

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SMOKE SUPRESSANT

Not much success Promotes oxidation

Al(OH)3, Mg(OH)2,Zinc Borate, Zn3(PO4)2Mo &Sn compoundsFunction as catalysts Modify pyrolysis mechanism

Benzene Smoke

PVC cis,trans polyene crosslinked polymer

all trans polyene char

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