A SEMINAR ON
Characterization of Polymer
PRESENTED BY
Mr. A.V.PATIL
I st sem M. pharm (Pharmaceutics)
GUIDED BY
Mr . S.G.BIDKAR
Department of Pharmaceutics
AISSMS COLLEGE OF PHARMACY
PUNE
23/09/2009
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CONTENTS
INTRODUCTION
History of Polymers
Definition
TYPES OF POLYMER
Classification of Polymers
Characteristics of Polymers
Properties of Polymers
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1. Characterization of Polymer
1. Chemical properties
2. Thermal properties
3. Mechanical properties
4. Other techniques
References
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INTRODUCTION
History of Polymers
In 1920 that German chemist Hermann
Staudinger (1881–1965)
• Rewarded with the 1953 Nobel Prize in
Chemistry
Made his macromolecular hypothesis,
suggesting that polymers are molecules
formed by the permanent attachment of
countless smaller molecules.
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Definition
Polymers are substances whose molecules
have high molar masses and are composed of a
large number of repeating units
The number of repeating units in one large
molecule is called the degree of polymerization.
Materials with a very high degree of
polymerization are called high polymers.
Polymers consisting of only one kind of
repeating unit are called homopolymers.
Copolymers are formed from several different
repeating units.
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TYPES OF POLYMER
NATURAL POLYMER
EX- proteins, starches, cellulose, and latex
SYNTHETIC POLYMER
EX- Polymethyl methacrylate
Polystyrene Polyvinyl Chloride
Polystyrene
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Classification of Polymers
According to the mechanical response at
elevated temperatures
•Thermoplasts
polymers soften when heated and harden
when cooled
•Thermosets:
Thermosetting polymers become soft during
their first heating and become permanently hard
when cooled. They do not soften during
subsequent heating.
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Characteristics of Polymers:
Low Density
Low coefficient of friction
Good corrosion resistance
Good mouldability
Excellent surface finish can be
obtained
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Can be produced with close
dimensional tolerances
Economical
Poor tensile strength
Low mechanical properties
Poor temperature resistance
Can be produced transparent or in
different colors
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Properties of Polymers:
Chain length - in general, the longer the
chains the stronger the polymer;
Side groups - polar side groups give stronger
attraction between polymer chains, making the
polymer stronger;
Branching - straight, unbranched chains can
pack together more closely than highly
branched chains, giving polymers that are
more crystalline and therefore stronger;
Cross-linking - if polymer chains are linked
together extensively by covalent bonds, the
polymer is harder and more difficult to melt.
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Polymer characterization
1 Chemical structure
2 Thermal properties
3 Mechanical and dielectric spectroscopy
4 Morphology
5 Other techniques
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Chemical properties
Molecular weight distribution
Additives analysis
Volatile organic compounds and odors
Residual monomers
Identification and quantitation of formulation components
Water content
Identification and determination of structural polymer
design (branding, copolymer, composition, functionality and
end capping)
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complex chemical structure of polymers
polymeric material typically consists of a distribution
of molecular sizes and sometimes also of shapes
Chromatographic methods like
size exclusion chromatography often in combination
with Low-angle laser light scattering (LALLS)
viscometry can be used to determine the molecular
weight distribution as well as the degree of long
chain branching of a polymer,
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Thermal properties
THREE MAIN THERMAL ANALYTICAL TECHNIQUES
•THERMOGRAVIMETRY (TG).
•DIFFERENTIAL SCANNINGCALORIMETRY (DSC).
• DYNAMIC MECHANICAL ANALYSIS (DMA)
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Thermogravimetry (TG)
“It is a technique whereby the weight of
the substance, in an environment heated or
cooled at controlled rate, is recorded as
function of time or temperature.”
Types of Thermogravimetry:
1. Isothermal thermogravimetry.
2. Quasistatic thermogravimetry.
3. Dynamic thermogravimetry.
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Principle
In this method a substance is heated from lower
temperature to higher temperature at a fixed rate
of heating. The changes in weight of the substance
as it is heated to higher temperature are recorded
as a function of sample temperature.
The graphical representation of weight as a
function of temperature is called as
thermogram.The weight should be plotted on
ordinate with weight decreasing downwards &
temperature on the abscissa increasing from left
to right.
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It can be concluded that thermogravimetry is
concerned with change in weight of the
material as its temperature changes.
First, this determines the temperature at
which the material loses weight. This loss
indicates decomposition or evaporation of the
sample.
Second, the temperature at which no weight
loss takes place indicates stability of the
material. These temperature ranges are
physical properties of the chemical
compounds & can be used for their
identification.
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Instrumentation of Thermogravimetry
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Differential Scanning
Calorimetry (DSC)
Differential scanning calorimetry or DSC is a
thermoanalytical technique in which the
difference in the amount of heat required to
increase the temperature of a sample and
reference are measured as a function of
temperature. Both the sample and reference
are maintained at nearly the same
temperature throughout the experiment.
Generally, the temperature program for a DSC
analysis is designed such that the sample
holder temperature increases linearly as a
function of time.
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Heat flux DSC
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Principle
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APPLICATION
Changes in the compositional and
structural parameters of the material usually
affect its melting transitions or glass
transitions and For semicrystalline polymers it
is an important method to measure
crystallinity.
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Interpretation:-
Tolbutamide and PEG 6000 form a eutectic with a composition
of 30 % TBA and 70 % PEG 6000 with the same melting point
as the PEG 6000 used.
The peak A at about 39 0c corresponds to a solid – solid
transition of tolbutamide.
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Evaluation :- The onset temperatures and the heats of fusion
ΔH are evaluated from the melting curves.
Sample onset/ΔH Peak A0c Peak A Peak B0c Peak B Peak C0c Peak C
J/g J/g J/g
TBA 100 % 39 8 - - 127 93
TBA 90%PEG 10 % 39.1 7.4 53.7 19.8 121.1 75
TBA 70%PEG 30 % 39.3 5.8 53.2 51.6 109 48
TBA 50%PEG 50 % 39.4 3.9 54.3 93.9 81.6 22.8
TBA 30%PEG 70 % 39.5 1.5 55.9 138.8 - -
TBA 10%PEG 90 % 39.5 0.3 55.3 166.7 - -
PEG 100 % - - 55 178 - -
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Phase Diagram.
It describes relationship between melting
temperature and composition of multi
component system.
To construct phase diagram mixtures of
components with different composition are
measured with DSC & data is evaluated.
Samples:- Tolbutamide and PEG 6000 as well
as mixtures.
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The phase diagram can be constructed by plotting the
onset temperature against the concentration
of TBA (in weight present)
The solid –solid transition of TBA occurs at about 390c
Above 54 0c either the liquid or the solid phase is present depending on
the TBA concentration
The dotted lines are extrapolations.
Conclusion:- Phase Diagram of Binary mixtures can be determined by26DSC
Dynamic Mechanical
Analysis
The Q800 utilizes state-of-the-art, noncontact,
linear drive technology to provide
precise control of stress, and air bearings for
low friction support. Strain is measured using
optical encoder technology that provides
sensitivity and resolution. The Q800 is ideal
for high-stiffness applications including
composites.
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Morphology
Morphological parameters-
Osmometery
Light Scattering
Viscometry
Gel permeation chomatography
mesoscale (nanometers to microns) are very
important for the mechanical properties of many
materials.
Transmission Electron Microscopy in combination
with staining techniques,
Scanning Electron Microscopy,
Scanning probe microscopy
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OSMOMETRY
Method Is used to determine number average
molecular weight Mn.
Only osmatic pressure is sensitive enough to
measure high molecular weight characteristic
of polymer.
Semipermiable membrane through which
solvent can pass ,which exclude polymer
molecule.
One filled with pure solvent and one filled
with polymer solution
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Activity of solvent in two compartment is
different bcoz polymer molecule
Osmatic pressure driving solvent into polymer
solution compartment will develop.
Osmatic pressure for ideal solution
∏∕C≈RT/Mn
To obtain Mn, ∏/c is plotted as function of C
and extrapolated to C=0
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Osmometers (UIC)
The Model 833 Vapor Pressure Osmometer is an
effective, easy to use tool for the determination of
number average molecular weights of any non-
volatile solute in the range of 100-25,000 Daltons.
The Model 231 Membrane Osmometer has the
ability to determine number average molecular
weights of any solute in the range of 20,000-
1,000,000 Daltons
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Light scattering
Scattering of light by liquid can be related to
local fluctuation in density due to thermal
motion of molecule
With solution addition scattering arises from
local fluctuations in the conc. Of the solute.
Measurement of light scattering of dilute
polymer solution it is possible to drive the
average molecular weight Mw.
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Simultaneous dynamic and
static light scattering system
The ALV / CGS-8F Compact Goniometer is the
common platform for a variety of different
goniometer systems. Based on a rotary disk
allowing finest angular steps to be performed
(rather than a rotary arm) it has four detection
angles separated each by 34° in angular space to
allow simultaneous measurement of Staticand
Dynamic Light Scattering at higher solution.
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Rheometer
(TA Instruments)
The AR-G2 Rheometer is equipped with an
environmental chamber for determining the
rheology of a sample under controlled
conditions. It has a built in viewer so that
samples can be monitored through out the
experiment.
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Gel permeation chomatography
Polymer molecules separated according to
their size
Sephadex, Bio-Gel (cross-linked
polyacrylamide), agarose gel and Styragel
are often used based on different separation
Measuring not only molecular weight but also
molecular weight distribution
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Dilute polymer solution pumped through a
series of columns containing porous beds
with different pore sizes.
Small molecule take longest path and largest
molecule take shortest path through columns
Highest molecule weight species emerges
first and lowest mol.wt species will emerges
last.
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Mechanical properties
Determined by stress-strain relationship
Stress-stretching force applied to sample
Strain-elongation of sample under a given
stress.
stress-strain relation in polymer are time
dependent
Specimen clamped to Instron tester and
measuring force that specimen exerts on load
cell
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ig-stress-strain curve for thermoplastic material (polyethyle
STRESS
STRAIN
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Fig-characteristic stress-stain curve for five
different type of polymeric material
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Other techniques
Solid state NMR
Spectroscopic techniques: IR, FTIR etc.
The VERTEX 70 FTIR has a spectral range
from 30 cm-1 in the far IR, through the near
IR and up to the visible spectral range at
25,000 cm-1. The large sample chamber
allows for a wide range of accessories with
temperature and environmental controls.
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References
Alb, A.M.; Drenski M.F.; Reed, W.F. "Perspective automatic continu
Polymer International,57,390-396.2008
US patent 6052184 and US Patent 6653150, other patents
pending
Retrieved from
http://en.wikipedia.org/wiki/Polymer_characterization
Instrumental Methods of Chemical Analysis by B.K.Sharma,
Twenty first edition 2002 Page No.232-249
Instrumental Methods Of Chemical Analysis By Gurdeep
R.Chatwal,Sham K Anand,Reprint 2005 Page No.2.701-2.738
Remington’s Pharmaceutical Sciences,20th Edition,Lippincott
Williams & Wilkins 649,709
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Chemical structure
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