This document discusses rheology modifiers, which are additives that control the flow properties of liquid formulations. It defines rheology and viscosity, and describes different types of rheology modifiers including inorganic, organic, associative, and non-associative modifiers. Quality parameters for rheology modifiers like viscosity, yield stress, and viscoelasticity are explained. Examples of specific rheology modifiers are provided like HEUR, Caesalpinia spinosa gum, and Carbomer. Methods for analyzing rheology modifiers including their structures are also summarized.

1. DELHI PHARMACEUTICAL SCIENCES AND
RESEARCH UNIVERSITY
QUALITY PARAMETERS AND ANALYSIS OF RHEOLOGY MODIFIERS
PRESENTED BY :- PRESENTED TO :-
KUMARI SUPRIYA Dr . SUSHMA TALEGAONKAR
M.PHARMA ASSOCIATE PROFESSOR
COSMECEUTICS (2nd SEM)

2. CONTENT
• Rheology
• Rheology modifiers.
• Types of rheology modifiers.
• Rheology modifier for water based and solvent based systems.
• Quality parameters of rheology modifiers.
• Example of rheology modifiers.
• Analysis of rheology modifiers.
• References.

3. RHEOLOGY
• Rheology is the science of deformation and flow within a material. It is a branch of
physics which deals with the deformation and flow of materials, both solids and
liquids.
• VISCOSITY:-
o The viscosity of a fluid is a measure of its resistance to deformation at a given rate.
For liquids, it corresponds to the informal concept of "thickness": for example,
syrup has a higher viscosity than water.

4. RHEOLOGY MODIFIERS
• Rheology Modifiers :- These are also known as thickeners . These are organic or
inorganic coating additives that control the rheological characteristics of the liquid
formulation. In coating technology, rheology modifiers are mainly used to provide
either pseudoplastic or thixotropic properties.
• The primary functional materials of a formulation, such as emulsifiers and oils, are not
sufficient to impart long-term stability, thickening, and a desirable rheology. In this
case, polymeric rheology modifiers are typically employed.

5. TYPES OF RHEOLOGY MODIFIERS
Rheology Modifiers
Inorganic Organic
Clay
Fumed Silica
Speciality
Clays
Cellulosic
Synthetics

6. TYPES OF RHEOLOGY MODIFIERS contd.
• ORGANIC RHEOLOGY MODIFIERS :- Organic rheology modifiers are more
diverse than inorganic ones. They can be subdivided into products based on natural
raw materials, like cellulose or xanthan, and products based on synthetic organic
chemistry, like polyacrylates or polyurethanes. And synthetic one can be divides as
– a) Associative rheology modifiers b) Non associative rheology modifiers.
• Associative rheology modifiers :- These thicken by non-specific interactions of
hydrophobic end-groups of a thickener molecule both with themselves and with
components of the coating. They form a so called “physical network”.
• Non associative rheology modifiers :- These act via entanglements of soluble,
high molecular weight polymer chains (“hydrodynamic thickening”). The
effectiveness of a non-associative thickener is mainly controlled by the molecular
weight of the polymer. Formulations thickened non-associatively have
pseudoplastic rheology with highly elastic properties.

7. TYPES OF RHEOLOGY MODIFIERS contd.
• INORGANIC RHEOLOGY MODIFIERS :- The most common types of modified
and unmodified inorganic rheology modifiers are attapulgite clays, bentonite clays,
organoclays , and treated and untreated synthetic silicas . Most inorganic thickeners
and rheology modifiers are supplied as powders.
• Inorganic rheology modifiers tend to have high yield values and are characterized as
thixotropes.

8. RHEOLOGY MODIFIERS FOR WATER BASED
AND SOLVENT BASED SYSTEMS
RHEOLOGY
MODIFIERS
WATER BASED SOLVENT BASED
CELLULOSIC
ACRYLIC
HEUR
ORGANOCLAYS
POLYAMIDES
FUMED SILICA

9. QUALITY PARAMETERS OF RHEOLOGY MODIFIERS
• MAIN PARAMETERS :- VISCOSITY
YIELD STRESS
VISCOELASTICITY
 VISCOSITY :- A primary function of rheology modifiers is to increase viscosity of the
solvent, such as water. Viscosity is a measure of the resistance to flow when a shear
stress is applied. A Non-Newtonian fluid is a fluid that does not follow Newton's law of
viscosity, i.e., constant viscosity independent of stress. A Newtonian fluid is a fluid in
which the viscous stresses arising from its flow, at every point, are linearly correlated to
the local strain rate—the rate of change of its deformation over time.

10. QUALITY PARAMETERS OF RHEOLOGY
MODIFIERS contd.
• Shear-thickening liquids, whose viscosity increases with the rate of shear strain.
• Shear-thinning liquids, whose viscosity decreases with the rate of shear strain.
• Thixotropic liquids, that become less viscous over time when shaken, agitated, or
otherwise stressed.
• Rheopectic (dilatant) liquids, that become more viscous over time when shaken,
agitated, or otherwise stressed.
• Bingham plastics that behave as a solid at low stresses but flow as a viscous fluid at
high stressed.

11. QUALITY PARAMETERS OF RHEOLOGY
MODIFIERS contd.
• APPARATUS FOR MEASURING VISCOSITY :-a) Concentric cylinders/
( type of Rotational viscometer)
b) Cone-and-plate
c) Parallel plate
d) Brookfield viscometer
Concentric cylinder Cone and plate

12. QUALITY PARAMETERS OF RHEOLOGY
MODIFIERS contd.
Parallel plate Viscometer Brookfield Viscometer

13. QUALITY PARAMETERS OF RHEOLOGY
MODIFIERS contd.
• YIELD STRESS :- A fluid with a yield point begins to flow only when the external
forces acting on it are larger than a certain shear stress commonly known as yield
stress,τo.
• The yield stress of personal care formulations is used to estimate the suspending power
of the rheology modifier and to predict the shelf life of a product.
• VISCOELASTICITY :-Viscoelasticity is the balance between the viscous and the
elastic components of materials. Elastic materials deform when subjected to an applied
force, and the deformation reverses completely and spontaneously when the applied
force is removed. Viscous materials deform when subjected to an applied force, and
the deformation stops when the applied force is removed.

14. QUALITY PARAMETERS OF RHEOLOGY
MODIFIERS contd.
• Viscoelasticity can be measured with a rotational viscometer or a rheometer
using an oscillatory technique.
• The relationship between the viscous component and the elastic component is
described by the ratio, tan δ, of the storage or elastic modulus (G’) and loss or
viscous modulus (G”).
• Rheometer- A rheometer is a laboratory device used to measure the way in
which a liquid, suspension or slurry flows in response to applied forces. It is
used for those fluids which cannot be defined by a single value of viscosity
and therefore require more parameters to be set and measured than is the case
for a viscometer.
• Rotational viscometers use the idea that the torque required to turn an object
in a fluid is a function of the viscosity of that fluid. They measure the torque
required to rotate a disk or bob in a fluid at a known speed.

15. QUALITY PARAMETERS OF RHEOLOGY
MODIFIERS contd.
Rotational viscometer Rheometer

16. EXAMPLES
• FEW EXAMPLE OF RHEOLOGY MODIRIERS :-
 HEUR
 CAESALPINIA SPINOSA GUM
 WORLEE AQUA THIX 100
 CARBOMER
 HYDROPHOBICALLY MODIFIED ALKALI SWELLABLE EMULSION(HASE)
 CAPRIC TRIGLYCERIDE
 CASTOR OIL DERIVATIVES
 POLYAMIDES
 CALCIUM SULFONATES

17. ANALYSIS OF RHEOLOGY MODIFIERS
• HEUR :- Hydroxyphobically modified ethoxylated urethane
• STRUCTURE :-
• HEUR rheology modifiers are widely used in waterborne coatings for their desirable
rheological and application properties. They consist of a water soluble polymer
backbone that contains two or more hydrophobic groups . It is used in nail lacquers.

18. ANALYSIS OF RHEOLOGY MODIFIERS contd.
• Caesalpinia spinosa gum :-Caesalpinia spinosa flour an odorless white to ivory-
colored powder, has been largely used in the cosmetic industry as a thickening
agent. It is mainly used in products like – Shower gel , Hair mask , O/W foundation
etc.
• STRUCTURE:-

19. ANALYSIS OF RHEOLOGY MODIFIERS contd.
• WorléeAqua Thix 100 :- WorléeAqua Thix 100 is a liquid acrylic dispersion
designed to thicken, suspend and stabilize cleansing products containing low and
high levels of surfactants or electrolytes. It offer emulsion stability and suspending
of pigments in skin and sun care products and enhances pigment distribution in
color cosmetics resulting in pleasant aesthetics and high coverage. It is a cost-
effective and easy to handle product with numerous benefits. It is used for
thickening of shower gel.

20. ANALYSIS OF RHEOLOGY MODIFIERS contd.
• CARBOMER :- Carbomer also known as polyacrylic acid .It is one of the most
efficient and widely used thickeners in cosmetic applications, including hair styling.
Carbomer offers the best performance for thickening in combination with PVP, there
are limitations in styling performance, such as low setting power, low humidity
resistance, running of the gel on application and visible flaking on hair.
• STRUCTURE :-

21. ANALYSIS OF RHEOLOGY MODIFIERS contd.
• HASE- HYDROPHOBICALLY MODIFIED ALKALI SWELLABLE
EMULSION.
• Hydrophobically modified alkali-soluble emulsion (HASE) polymers are an
important class of rheology modifiers for waterborne coatings applications. They
are typically prepared as polymers by emulsion polymerization of ethyl acrylate
(EA), methacrylic acid (MAA), and an associative macromonomer. It is used nail
lacquers.

22. ANALYSIS OF RHEOLOGY MODIFIERS contd.
• CAPRIC TRYGLYCERIDE-
• Caprylic / capric triglyceride is an oily liquid made from palm kernel or coconut oil.
It is a mixed ester composed of caprylic and capric fatty acids attached to a glycerin
backbone. It is used as skin-replenishing agent in moisturizer.

23. ANALYSIS OF RHEOLOGY MODIFIERS contd.
• POLYAMIDES-
• A polyamide is a macromolecule with repeating units linked by amide bonds.
Polyamides occur both naturally and artificially. Example polyamides are protein and
can be made through nylon, sodium poly(aspartate).
• And used in cosmetics like creams, lotion, stick, sunscreen etc.

24. ANALYSIS OF RHEOLOGY MODIFIERS contd.
• CALCIUM SULFONATES-
• A calcium sulfonate is a salt or ester of a sulfonic acid. It contains the functional
group R-SO3−, where R is an organic group. Sulfonates are the conjugate base of
sulfonic acids.
• It is used in hair care, sun protection range and skin care products.

25. REFERENCES
• https://www.researchgate.net/publication/305903042_PART_422_RHEOLOGY_M
ODIFIERS_AND_CONSUMER_PERCEPTION.
• http://storage.dow.com.edgesuite.net/DCM/pdf/Next-Generation-HEUR-
Technology_CoatingsTech_March2014.pdf.
• https://insights.basf.com/files/BASF_ED_RheologyModifiers_download.pdf.
• https://www.coating-additives.com/product/coating-
additives/downloads/rheological-additives.pdf.
• https://www.crodapersonalcare.com/en-gb/products-and-applications/skin-
care/rheology-modifiers.