Plasticizers in Cosmetic Technology

D.P. GhoshASST. Prof.

KSOPGHAZIABAD

INTRODUCTION

A plasticizer is a substance which when added to a material,

usually a plastic, makes it flexible, resilient and easier to

handle.

They are colorless, odorless liquids produced by a simple

chemical reaction, where by molecules of water are eliminated

from petrochemical products.

They are not just additives. They are major components that

determine the physical properties of polymer products.

Introduction

3

Plasticizers are relatively low molecular weight

materials which have a capacity to alter the

physical properties of a polymer to render it more

useful as film forming agents.

The polymers used as film forming agents are

relatively brittle in nature at room temperature

and pressure.

The function of plasticizer is to make the

polymer more pliable and soft and thereby

enhancing the flexibility and plasticity to the

films.

They modify the physical and mechanical

properties of film by enhancing the mobility of the

Cont'd

4

Plasticizer are added in order to reduce the glass

transition temperature, this addition of the

plasticizer facilitates the thermal stability of the

ingredients.

The intensity of particle coalescence and the

quality of the resulting final film so formed

entirely depends on the type and the

concentration of plasticizer added to the coating

dispersion.

The efficiency of a plasticizer is intensely related

to its chemical structure and the extent and rate

of interaction with the polymeric material present

in the formulation.

Physicochemical properties of the films mainly

the water uptake and erosion, solid-state

DEFINITION :

A plasticizer or softener is a substance incorporated in a

material (usually a plastic) to increase the flexibility,

elongation, workability, dispensability.

It may reduce the melt viscosity, lower temperature of second

order transition or lower the elastic modulus of the product.

A Plasticizer is a distinct polymer additive.

There are more than 300 different types of plasticizers

available . The most commonly used plasticizers are ester like

phthalates, adipates and trimellitates.

IDEAL PROPERTIES OF PLASTICIZERS:

• It should be flexible resilient and easier to handle.

• It should be non volatile with high boiling point.

• It should not come out from materials to which it is added.

• Plasticizers used for internal purpose should be non toxic.

• Lower the tensile strength and softening temperature, of the polymeric materials to which it is added.

• Polar with a high Mol. Wt. ester type organic compounds.

• Reduce internal friction between polymer chain.

IDEAL PROPERTIES….

• It should reduce the brittleness, improve flow, flexibility, and increase toughness, shear strength, and impart resistance to the polymeric film coating.

• It should lower the glass transition temperature of the polymeric film coating. It should reduce the viscosity of materials to which it is added.

• it should impart permanent properties such as liability, shock resistance, hand drop.

• The main role of the plasticizer is to improve mechanical properties of the polymers by increasing flexibility, decreasing tensile strength and lowering the second order transition temperature.

GLASS TRANSITION TEMPERATURE(Tg):

• The temperature at which the glassy polymer becomes rubbery

on heating and rubbery polymer reverts to glassy on cooling is

called the glass transition temperature.

• Polymer in rubbery state are very viscous liquids with

relatively high freedom of rotation round the carbon-carbon

bonds in the backbone with in the constraint of tetrahedral

bond angle.

• The temperature is high enough so that most bonds capable of

overcoming potential energy barrier against rotation. This

rotational freedom results in very flexible chains.

plaPlasticizer

10% plasticizer 20%plasticizer

Triethyl citrate

Acetyl triethyl citrate

Tributyl citrate

Acetyl tributyl citrate

Triacetin

Tg of unplasticized

film is 55ºc

34.3

37.0

38.5

38.2

42.2

12.8

17.5

20.5

22.2

27.4

Tg of Eudragit RS 30D(ºc)

GLASS TRASITION TEMPERATURE OF EUDRAGIT RS 30 D POLYMERIC FILMS

Why do we need plasticizers?

Almost all the film forming agents or polymers are

brittle in nature do to their complex structure.

Most commonly used polymers are the cellulose

derivatives or cellulose related compounds like

HPMC, MC, EC, Nitrocellulose, HPMCP etc.

These polymers are widely used as film forming

materials as they:-

Produce transparent films

Produce intact films

10

Cont’d

They have lower values for water vapor

permeability rate.

They have lower values for oxygen

transmission rates.

They can be structurally modified to

achieve sustained release ,like HPMC can

be converted to HPMCP for enteric

coating.

But due to presence of multiple polymeric

strands within a single molecule of polymer

makes them brittle. 11

Cont’d

When such a material is applied as a film coat

on to tablet a smooth film is not be obtained.

This condition necessitates the addition of

plasticizers to the coating/Film forming

dispersions.

The addition of plasticizers to polymeric

material causes them to diffuse within the

polymers and cause polymer deformation and

coalescence into homogeneous films.

The effectiveness of plasticizers on polymeric

dispersion depends upon polymer

compatibility and the permanence of

plasticizer during the course of shelf life, or

12

Effect of Plasticizers

• Easy melt

• Improve flexibility

• Increase Softness and Flexibility.

• Improve Process ability.

• Alters Softening point, Tensile Strength,

Elongation at break & Impact.

Mechanism of action

14

The mechanism of action of plasticizers is

defined as to interpose between every individual

strand of polymer and thereby causing

breakdown of polymer -polymer interactions.

The tertiary structure of the polymer is modified

into more porous, flexible and with less cohesive

structure.

Plasticizers soften and swell the polymer (latex

spheres) which aids in overcoming their

resistance to deformation.

As a result the plasticized polymer would deform

at a lower tensile force as compared to without

plasticizer. This enhances the polymer -

plasticizer interaction.

Cont'd

15

This effect in turn enhances the film elongation

effect.

This interaction to a greater extend depends

upon the glass transition temperature of

polymers. Glass transition temperature, Tg is the

temperature at which hard glassy polymer is

converted into a rubbery material.

All polymers have higher glass transition

temperatures and addition of plasticizers reduces

the glass transition temperature.

MECHANISM.......

16

As plasticizers usually possess relatively long alkyl chains,they have the effect of screening the polymer chains fromeach other, thereby preventing them from re-forming thechain-chain interactions which give the unplasticized polymerits rigidity.

PLASTICIZATION THEORIES

Lubricity Theory: Plasticizer acts as a lubricant,reducing intermolecular friction between polymermolecules responsible for rigidity of the polymer.

Gel Theory: Polymers are formed by an internalthree-dimensional network

Free Volume Theory: Plasticizer lowers the glasstransition temperature (Tg) of the polymer.

Mechanistic Theory: Plasticizer molecules are notbound permanently to the polymer molecules form.

17

LUBRICITY THEORY:

A “dry” polymer, a resin without plasticizer, is rigid because friction exists between its chains, binding them into a network.

When the polymer is heated in order to be plasticized, the binding is weakened and the smaller plasticizer molecules are able to slip in between the chains.

When the polymer cools, the plasticizer molecules act as a lubricant between the chains, allowing them to “slip.”

GEL THEORY:

The plasticizer molecules break up the polymer-polymer interaction by getting in between the chains and “obscuring” these interaction sites from the polymer molecules.

THE FREE VOLUME THEORY:

• The free volume of a polymer can be described as the “empty internal space” available for the movement of the polymer chains.The free volume of a polymer greatly increases when it reaches the glass transition temperature.

• At the glass transition temperature, the molecular motion begins to occur, which corresponds to an increase in the free volume of the polymer.

• These plasticizer molecules are having low glass transition temperature than the polymer, so that Tg of the resulting mixture will be lower.

Lubricity Theory

Assumes the rigidity of the resin (pure polymer) arises from “intermolecular friction.”

Plasticizer molecules are introduced on heating.

At room temperature, these molecules act as lubricants for the polymer chains.

Gel Theory

Resin-resin interactions occur at “centers of attachment.”

Plasticizer molecules break these interactions and masks the centers from each other, preventing re-formation.

This theory is not sufficient to describe interaction– should be combined with Lubricity Theory.

Free-Volume Theory

Free volume: “internal space” available in the polymer for the chains to move.

This volume increases sharply at the glass transition temperature, Tg.

Plasticizer is meant to decrease the glass transition temperature, imparting increased flexibility to polymer at room temperature.

TYPES OF PLASTICIZERS

These are two types

Internal plasticizers

External plasticizers:

Primary plasticizers

Secondary plasticizers

CLASSIFICATION

Majority of plasticizers are Organic Esters.

24

According to technique of Plasticization

External Internal

Not physically bound to

polymer & can evaporate,

migrate or exude from

polymer.

Group constituting a part

of a basic polymer chain,

which may incorporate

bet. chain

INTERNAL PLASTICIZERS:

• A rigid polymer may be internally plasticized by chemically

modifying the polymer or monomer so that flexibility polymer is

increased.

• The process by which Tg of rigid polyvinylchloride is lowered

through copolymerization, is called internal plasticization.

EXTERNAL PLASTICIZERS:• These are high boiling liquids, non volatile and having low vapor

pressure.

• They must soluble in polymer and reduce the Tg of polymer below

room temperature rendering it softer and flexible

• They acts as lubricants between the polymer chains, facilitating

slippage of chain under stress.

Types of Plasticizer (I)

Internal vs. External

Internal plasticization occurs via chemical interactions.

Copolymerization is one type of internal plasticization.

External plasticization occurs via physical interactions.

External is the most common: cost, ease of processing.

CLASSIFICATION

Other

27

Conventionally classified as

SecondaryPrimary

Sufficient level of

compatibility to be used

give desirable effect.

directly interact with

chain.

Limited compatibility & can

exude if used alone.

Incorporate with primary

plasticizer.

PRIMARY PLASTICIZERS:

Also called as chemical plasticizers, when added to

polymer, will cause the properties of elongation and softness

of the polymer to be increased.

SECONDARY PLASTICIZERS:

Also called as plasticizing oils. They are not used

alone but when combined with primary plasticizers will

enhance the plasticizing performance of the primary

plasticizer.

Types of Plasticizer (II)

Primary vs. Secondary

Primary Plasticizer affects resin properties.

Secondary is a “Plasticizer-plasticizer”: used to increase the effectiveness of the primary plasticizer.

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.

SELECTION CRITERIA

Choice of plasticizer depends upon the properties

required in final product, the application technology

used to make it !!

Prize boundaries present for product process.

Stability in processing & service condition.

Compatibility & ease of mixing.

Toxicity. 32

PLASTICIZER EFFICIENCY..

The measure of concentration of plasticizer require

to improve a specifies softness of the polymer.

Plasticizer efficiency increases as carbon number

of alcohol chain decreases.

For phthalates,

BBP>DIHP>DOP>DINP>DIDP

Linear plasticizer is more efficient.

33

Plasticization in Cosmetics

Polymers used in cosmetics are generally amorphous in nature.

Unfortunately Glass transition temperature of most of the polymers are in excess of conditions exposed for the cosmetic manufacturing.

Thus one needs to incorporate plasticizer basically for two main reasons:-

1. Modification of polymer properties so as to impart flexibility which reduces the Tg of amorphous polymer.

2. To facilitate the processing of dosage form at substantial temperature conditions to protect the integrity of active ingredient.

Timeline (history)

FirstPlasticizer

1860 1930

Phthalates Introduced

1980’s

DEHP Declared Carcinogenic

2001

IARC Re-classifies DEHP

as non-carcinogenic

1998

European Parliament calls for alternatives to phthalates

Limitations

36

(A) LEACHING EFFECT-

The major trouble encountered during the

plasticizing of polymers is the leaching of the

plasticizer from the film.

This leaching effect of Plasticizer is dependent on

the type and concentration of dissolution medium.

This eventually results in drastic alteration of film

properties.

This tendency of plasticizers can be well

demonstrated from the In vitro dissolution studies

with cast films of Eudragit® RS/RL had leached

out the water-soluble plasticizers when the

amount of hydrophilic polymer in the film was

increased than the normal.

Cont’d

37

Permanence is an attribute taken in

consideration as loss of plasticizer during storage

of plasticizers which in turn can hamper integrity

of coated tablets.

The mechanism by which permanence occurs is

said to be migration via diffusion process.

The molecular size and shape of the plasticizer

are highly important as small molecules migrate

faster than large ones. Also linear molecules

migrate faster than bulky, branched ones.

The highly solvating ones that produce an open

gel structure migrate at a faster rate.

Cont’d

38

Volatility was found to be one of the major cause.

Thus permanence due to leaching tendency of

plasticizers can be controlled by diffusion control.

This diffusion of plasticizer can be controlled by

incorporating a more non volatile plasticizer or

switching to a higher molecular weight plasticizer.

PLASTICIZERS IN FILM COATING:The commonly used plasticizers can be categorized into three groups:

1. Polyols:

(a) Glycerol (glycerin);

(b) Propylene glycol;

s(c) Polyethylene glycols PEG (generally the 200–6000 grades).

2. Organic esters:

(a) Phthalate esters (diethyl, dibutyl);

(b) Dibutyl sebacete;

(c) Citrate esters (triethyl, acetyl triethyl, acetyl tributyl);

(d) Triacetin.

3. Oils/ glycerides:

(a) Castor oil;

(b) Acetylated monoglycerides;

(c) Fractionated coconut oil

TYPES OF PLASTICIZERS:

• Phthalates

• Adipates

• Citrates

• Phosphate esters

• Polymerics

• Esters of glycol and polyhydric alcohols

• Sebacate nad azelate esters

• Secondary plasticizers

• Trimellitates

Plasticizers: Classification

Class Examples

Polyhydric alcohols Propylene glycol

Glycerol

Polyethylene glycol

Acetate esters Glyceryl triacetate

Triethyl citrate

Acetyl triethyl citrate

Phthalate esters Diethyl phthalate

Glycerides Acetylated monoglycerides

Oils Castor and mineral oil.

42

Classification of plasticizers

Depending on their properties they can be

classified as:-

Polyols

Glycerol

Propylene glycol

PEG 200-6000 grades.

Organic esters

Triacetin,

Diethyl phthalate (DEP),

Dibutyl phthalate (DBP) and

Tributyl citrate (TBC) 43

Cont’d Oils/ glycerides

Castor oil

Fractionated coconut oil

Acetylated monoglycerides.

Newer Plasticizers – DBS (Dibutyl Sebacate).

Can be used for the very plasticizing effect in

both aqueous and solvent based pharmaceutical

coatings.

Under this category both the hydrophilic as well

as lipophilic esters are available.

44

Properties of commonly used

plasticizers.

(A) PEGs

These are hydrophilic substances and soluble in

water.

In the conventional film coating the solid grades

of PEGs are used alone as hydrophilic

plasticizers.

Rate of release of water soluble drugs

decreases with increase in the molecular weight

of PEGs.

The PEG with molecular weight of 6000 and

above decreases plasticizing effect and

increases lubricant effect.

45

PHTHALATES

46

Most widely use as plasticizer.

Phthalates accounts 92% of all plasticizers.

A Phthalate ester derived from phthalic acid by an

esterification reaction.

Properties: Colorless Oily liquid ( like vegetable oil)

Ester odor, High boiling point, Inert and very stable over

long periods

PHTHALATES:

• Both ortho-phthalic and terephthalic acids are used to react with

alcohol to produce phthalate esters

• Alcohol used in the range from methanol(c1 up to c17.)

• When added to vinyl, phthalate molecules are tightly bound up

between the long vinyl molecules, making them slip and slide

against each other without sacrificing strength.

ADVANTAGES:

• Migration is less

• Readily biodegradable

• Does not cause any harm to body.

Cont’d

(C) DEP- Di ethyl Phthalate.

Used both as a solvent and plasticizer.

Non toxic, non irritant.

DEP is used as a plasticizer in film coating of

tablets , beads and granules at a concentration of

10-30% W/W of polymers.

Its is insoluble in water, soluble in ethanol, ether

and orgainc solvents.

It is volatile in nature.

48

Cont’d

(D) DBP- Dibutyl Phthalate.

Also known as kodaflex DBP.

Very soluble in acetone, benzene, ethanol, ether

and soluble in water.

Is principally used as a plasticizer.

But it has limited compatibility with the cellulose

acetate polymers.

49

A) DI-2-ETHYLHEXYL PHTHALATE:

Also known as di-octyl phthalate.

It is considered as the industry standard.

It is phthalate ester of alcohol 2-ethylhexanol.

Advantages

Low cost

Posses reasonable plasticizing efficiency, fusion rate , viscosity

Disadvantages:

It is toxic

DOP/DEHP

51

Primary use as plasticizer.

Insoluble in water, Boiling point: 386.9oc,Density:

0.9732 g/L, Molecular weight: 390.5618 g/mol.

Production: Phthalic anhydride with 2-ehaxenol:

C6H4(CO)2O + 2 C8H17OH → C6H4(CO2 C8H17)2 + H2O

Used in medical devices ,Toys, Pacifiers, Vinyl

Upholstery, Food containers, Table cloths, Shower

curtains.

B) DIISODECYL PHTHALATE(DIDP) AND DIISONONYL

PHTHALATE (DINP) :

These are prepared from oxo alcohols of carbon c9 and c10

These are used for heat resistant electrical cards, leather for car

interiors and PVC flooring in concentration of 25 to 50%.

ADIPATES:

Adipates are prepared from alcohols in the c8 to c10 range.

They are having improved low temperature performance and low

viscosity.

They are highly volatile, having high migration rate and are high

priced.

DINP

53

Mixture of chemical compounds consisting of various

isononyl esters & phthalic acid.

Properties :Insoluble in H2O,Soluble in most organic

solvents, Boiling point: 250Density: 0.98g/cc, Molecular

weight: 418.6 g/mol.

Use in Replacing DEHP in toys when initially

determined to be carcinogenic.

DIDP

54

Mixture of compounds derived from the esterification of phthalic acid & isomeric decyl alcohol.

Properties: density:0.96g/cc, melting point: -50, boiling point: 250-257c at 0.5KPa.

Uses in plastisol application, provides good initial viscosities & excellent viscosity stability.

CITRATES:

These include triethyl citrate, acetyl triethyl citrate, tributyl

citrate and acetyl tribuyl citrate

Tri butyl citrate is heat stable and does not discolour when

processed in compound resins.

These esters used in electrical coatings, food industry, hair

sprays and inks.

PHOSPHATES:

They show good compatibility with PVC.

They are having good low temperature performance, migration

resistance and improved fire retardency relative to phthalates.

Cont’d

(E) Triacetin

Also known as Triethyl glycerin or glycerol

triacetate.

Used as both plasticizer and a solvent.

Its an hydrophilic plasticizers.

This plasticizer is suitable for both aqueous and

solvent based polymeric coating of tablets,

granules and beads in concentration of 10-35%

by weight of polymer.

Miscible with water as well as in ether, ethanol,

chloroform etc.

56

Cont’d

(F) TEC- Triethyl Citrate.

It is a citric acid ethyl esters.

Also known as Citroflex 2.

Its is principally used as plasticizer.

It is effectively used in aqueous based coating in

Oral sustained or enteric coated tablets .

Miscible with water.

57

SEBACATES & ADIPATES

58

Dibutyl Sebacate is an organic chemical , a dibutyl ester of

sebacic acid.

Properties: density: 0.94g/cc, boiling point:344.5c , melting

point:-10c, flash point: 178c.

Used in food packaging industry, in plastics used for medical

devices, and for pharmaceutical applications,

TRIMELLITATE PLASTICIZERS -

59

Synthesized using one mole of trimellitic anhydride and 3

moles of an alcohol. The third alkyl group, compared to

phthalates, contributes higher molecular weight (low

diffusivity);the third ester group contributes sufficient polarity

to enhance compatibility with PVC.

Tri (2-ethylhexyl) Trimellitate

FATTY ACID ESTERS

Esters of fatty acids & monocarboxylic acids can be

used as viscosities depressant for PVC pastes &

also as secondary plasticizers for plasticized PVC.

Present in liquid form.

Stearic acid esters are used as plasticizers &

processing agent for various plastics & also as

lubricants for PS.

60

OLIGOMERIC/POLYMERIC PLASTICIZER

These extend the life of PVC products considerably

They reduce migration, extraction & volatility.

In these adipates are generally used in mixture with

other plasticizer to increase plasticization & improve

low temp. Properties.

Epoxied plasticizer (soybean oil & linseed oil) are

used as stabilizing plasticizer offering properties of

migration resistance in PVC compounds.

61

POLYMERICS:

• These are produced by reacting a dibasic carboxylic acids with one or more glycols.

• These are manufactured in a wide range of viscosities. With increasing viscosity, handling become more difficult.

• The optimum viscosities of some acids are

adipates-5600 cps, glutarates-12000 cps.

ESTERS OF GLYCOLS AND POLYHYDRIC ALCOHOLS:

• polyhydric alcohols are propylene glycol, glycerol, polyethylene glycol and Esters of glycols are glyceryl triacetate, tri ethyl citrate.

• These are water soluble and used in aqueous film coatings.

SECONDARY PLASTICIZERS:

• They are also known as extenders.

• The majority of these plasticizers include chlorinated

paraffin's, which are hydrocarbons chlorinated to a level of 30-

70%.

• The fire retardency and viscosity increases with chlorine

content.

• Other materials used are epoxidised soya bean oil and

epoxidised linseed oil.

• They acts as lubricants to pvc due to their epoxy content.

TRIMELLITATES:

• Common esters in these family are tris-2

ethylhexyltrimellitate,L810TM, an ester of mixed c8 and c10

linear alcohols.

Advantages:

• Low volatility

• Low migration rate.

SEBACATE AND AZELATE ESTERS:

• Di-2-ethylhexyl sebacate (DOS) and di-2-ethylhexyl azelate

(DOZ) are the most common members of this group, but

Diisodecyl Sebacate (DIDS) is also used. They give superior low

temperature performance than adipates.

Cont’d

(B) DBS- Dibutyl Sebacate.

These are esters of n-butanol and saturated

dibasic acids.

Principally used as plasticizers in film coating.

For film coating as a plasticizer, DBS is used in

10-30% concentration by weight of polymer.

Insoluble in water but soluble in ethanol, mineral

oil etc.

Quite suitable for solvent based coating

dispersions.65

Classification on basis of water

solubility.

(A) Water soluble

PEG

TEC

Triacetin

(B) Water insoluble are

DEP

DBS

DBP

ATEC –Acetyl-triethyl-citrate.

66

Cont’d Water soluble plasticizers make solutions

whereas the insoluble plasticizers are

emulsified into dispersions.

With insoluble plasticizers, their dispersion is

described as a 3 phase systems containing

water phase, polymer phase and plasticizer

emulsified droplets.

The rate and the extend of plasticizers uptake

by the colloidal polymers was explained by

conducting the effect of type and

concentrations of plasticizers on Aquacoat

and the plasticized films so formed were

characterised by HPLC.

It showed that the water soluble plasticizers

67

Cont’d Whereas the water insoluble plasticizers i.e.

DBS partitioned about 90% or more into the

polymer phase. And the rest form was present

as emulsified droplets.

Under such conditions when the plasticized

droplet containing coating dispersions are

sprayed onto the tablets they generate rough,

brittle and uneven films which potentially

alters mechanical properties and release

profile of drug from the coated dosage forms.

The rate of uptake of plasticizers by the

polymers is a function of plasticizing time. But

in case of water soluble plasticizers like

triacetin or TEC uptake is not affected by the

agitation time or mixing time.

68

Cont’d

But for water insoluble plasticizers like DBS

incomplete plasticizing is observed even after

long plasticization time for ethylcellulose latex.

To overcome this undesired effect we carry

out an additional step called “Curing Step” .

69

Conclusion Plasticizers play a very significant role on

mechanical properties, permeability of films and

release of drug from the coated products.

They do enhance flexibity and plasticity of films.

Therefore, the selection of a plasticizer for a film-

coating formulation is very important in the

process development and optimization of a

coated dosage form.

Curing conditions can facilitate the uniform

distribution of plasticizers.

Therefore, one needs to strike a balance between

the desired and undesired effects of the

plasticizer and optimize its concentration in the

coating formulation.

70

CONCLUSION:

Plasticizers are necessary for almost all polymers that are

currently used for film coating of tablets and beads.

Plasticizers reduce the brittleness, improves flow, impart

flexibility, and increase flexibility, and increase toughness,

strength, tear resistance of polymers.

Although there are many plasticizers used in chemical

industry, only a few plasticizers have been approved for

pharmaceutical applications due to environmental and human

health concerns attributed to plasticizers toxicity.

References1. Harry R.G., Reiger M.M., Harry’s Cosmeticology, Chemical publishing company.

Newyork

2. Balsam M.S., Sagarin E., Cosmetics: Science and Technology. Wiley Interscience.

Newyork

3. Rao Y.M., Shayeda, Cosmeceuticals, Pharma Med Press. Hyderabad

4. Paye M., Basel A.O., Maibach H.I., Handbook of Cosmetic Science & Technology,

Informa

Healthcare. Newyork

5. Sharma P.P., Cosmetics Formulation, Manufacturing and Quality control, Vandana

Publication Pvt. Ltd. Delhi

6. Poucher W.A., Butler H., Poucher’s Perfumes, Cosmetic & Soaps, Springer India Pvt.

Ltd. New

Delhi.

7. Nanda S., Nanda A., Cosmetic Technology, Birla Publication, Delhi.

8. SCCS's Notes of Guidance for the Testing of Cosmetic Ingredients and their Safety

Evaluation, 7th Revision. European Commission.

9. Indian Pharmacopoeia 2014(7th edition), Ministry of Health and Family Welfare,

Published by

Govt. of India.

THANK YOU

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