Presentation Contain Classification of Polymer and various Characterization and Evaluation Parameter for Manufacturing of Polymer.

1. CHARACTERISATION AND
EVALUATION OF POLYMER
CHANDRESH PATEL
M.PHARM

2. WHAT IS A POLYMER?
A polymer is a substance composed of molecules characterized by
the multiple repetition of one or more species of atoms or groups of
atoms (constitutional repeating units) linked to each other in
amounts sufficient to provide a set of properties that do not vary
markedly with the addition of one or a few of the constitutional
repeating units.”

3. CLASSIFICATION OF POLYMER
BASED ON ORIGIN OF POLYMER
BASED ON PRESENCE OF CARBON ATOM
CLASSIFICATION BY MONOMER COMPOSITION
BASED ON MICROSTRUCTURE
BASED ON CHAIN STRUCTURE
BASED ON PHYSICAL PROPERTY RELATED TO HEATING
CLASSIFICATION BY APPLICATION
CLASSIFICATION BASED ON KINETICS OR MECHANISM
BASED ON DEGRADATION OF POLYMER

4. CHARACTERISATION AND EVALUATION
MOLECULAR WEIGHT
oAlthough in principle the measurement of any colligative property
of a solution ( such as freezing point depression, elevation of boiling
point, or osmotic pressure) can be used to determine the molecular
weight of a dissolved solute, only osmotic pressure is sensitive
enough to measure the high molecular weights characteristic of
polymeric substances.

5. TECHNIQUESTODETERMINEMOLECULAR WEIGHT METHODS
Method Measured
Parameter
M.Weight
Measured
Upper Limit (g per
mole)
Membrane osmometry Osmotic pressure of
polymer solvent
Mn 5x10⁴
Light scattering (LS) Intensity of light
scattered by dilute
polymer solutions
Mw 1x10⁸
Gel permeation
chromatography (GPC)
Elution volume of the
polymer solution
through a GPC column
packed with porous
microparticles
Mn , Mw 1 x 108
Viscometry Flow time of polymer
solution through a
capillary
M v 1 x 108

6. OSMOMETRY
Osmotic measurements use a semipermeable membrane through
which the solvent can freely pass but which excludes polymer
molecules.
If this membrane separates two compartments, one filled with
pure solvent and the other with a polymer solution, the activity of
the solvent in the two compartments is different.

7.  Osmotic pressure is a colligative property, which means that it is
proportional to the concentration of solute. The van’t Hoff equation
is often presented in introductory chemistry for calculating osmotic
pressure (Π) from the moles of solute (n solute) that occupy a given
volume (V) and the absolute temperature (T) of the solution
∏= nRT/ V
According to equation, the molecular weight of a solute can be
obtained by plotting osmotic pressure divided by c versus
concentration and extrapolating the data back to c = 0.

8. LIGHT SCATTERING
Scattering of light by liquids can be related to local fluctuations in
density due to thermal motions of molecules.
 From measurements of light scattering of dilute polymer solutions
it is possible to derive the weight average molecular weight.
It is measured by applying Lord Rayleigh’s electromagnetic theory,
which shows that the intensity of scattering is proportional to the
square root of particle mass

9. VISCOMETRY
Unlike osmometry and light scattering which are absolute methods
in that they allow molecular weight determinations of unknown
polymers, viscometry is a relative method and requires calibration
with samples of polymer of known molecular weights.
 Determination of polymer molecular weight by measurement of
the viscosity of polymer solutions is based on the fact that, as
polymer molecular weight increases, so does the viscosity of its
solutions.
The viscosity is measured by timing flow of the solution between
two marks in various viscometers

10. GEL PERMEATION CHROMATOGRAPHY
This ia a procedure whereby polymer molecules are separated
according to their size. This method, also a relative method, is
capable of measuring not only molecular weight, but also molecular
weight distribution.
 MOLECULARWEIGHT IS DETERMINED ONLY IFTHE METHOD IS
FIRST CALIBRATED WITH POLYMER SAMPLES OF KNOWNWEIGHTS
ANDA PLOT OF MOL.WEIGHTVS RETENTIONTIME IS CONSTRUCTED.

11. THERMAL ANALYSIS
A true workhorse for polymer characterization is thermal analysis,
particularly
DSC-Differential scanning calorimetry
TGA-Thermogravimetric Analysis
Narrow peaks are indicative of 1st order transitions such as melt
temperature
2nd order transition like Tg occurs at inflection points Chemical
reaction are indicated by broad peaks

12. THERMOGRAVIMETRIC ANALYSIS
This method uses a thermo balance that is capable of measuring
the weight of a sample contained in a pan.
 The pan is placed in a furnace and the temperature of the furnace
is slowly raised, usually at 5 to 10 degree Celsius/ min.
The technique is used to determine thermal stability of polymers
and the upper limit of thermal stability is usually taken as the
temperature at which loss of the sample begins.

13.  It is unable to detect
chain cleavage that
produce degradation
fragments that are too
large for volatilization

14. DIFFERENTIAL SCANNING CALORIMETRY
(DSC) measures the energy necessary to establish a zero
temperature difference between the sample and an inert substance
DIFFERENTIAL SCANNING COLORIMETER This is useful technique for
measuring  glass transition temperature,  crystalline melting
points,  heats of fusion  heats of crystallization.

15. The sample and a reference substance, which does not undergo a
thermal transition in the temperature range of interest, are placed in 2
small metal containers and heated by individual electric heaters.
The temperature of both samples, are monitored by thermocouples, is
then gradually raised in such a manner that the temperature of sample
and reference remain the same.
In this way, transition temperatures can be very accurately measured
by monitoring the electric current going to the heaters.

16. THERMOMECHANICAL ANALYSIS
This measures deformation of a substance
under a non-oscillatory load as a function of
the temperature of the sample, which is
placed on a platform and contacted with a
probe.
It can conveniently measure transitions from
a glassy to a rubbery polymer and can also
measure softening temperature.

17. MECHANICAL PROPERTIES
It is determined by measuring their stress-strain relationship. Stress
is the stretching force applied to the sample and strain is the
elongation of the sample under a given stress.
Here the specimen is clamped in a tester that is capable of
extending the specimen at a chosen constant rate and measuring the
force that the specimen exerts on a load cell.
 In the initial phase, application of stress causes a moderate
elongation to the yield point, after which significant elongation takes
place without greatly increased stress. Elongation then continues
until the specimen breaks.

18. REFERENCE
The Controlled Drug Delivery, 2nd edition revised and expanded
edited by Robinson, J.R., & Lee ,V. H , Marcel Dekker, page- 164- 176
Polymer in drug delivery by Tayler and Francis group
Hetch G. Remington : the science and practice of pharmacy, vol 2,
page no 832- 833.
http://en.wikipedia.org