CHARACTERIZATION, ANALYSIS, AND TESTING Flashcards
analytical branch of polymer science
Polymer characterization
technique used to determine the
molecular properties, structure, and behavior of polymers
Polymer characterization
The information obtained from polymer characterization can also be
used for
process control and product quality assessment.
Characterization techniques are typically used to determine
molecular mass, molecular structure, morphology,
thermal properties, and mechanical properties
____________ molecular weights are observed in polymers with
very long chain
extremely large
The distribution of molecular masses can be summarized by the
number average molecular weight, weight average molecular weight,
and polydispersity
Some of the most common methods for determining these
parameters are
colligative property measurements, static light
scattering techniques, viscometry, and size exclusion
chromatography
There are four molecular weight
averages in common use
number-average molecular
weight, Mn
; the weight-average
molecular weight, Mw
; the zaverage molecular weight, Mz
;
and the viscosity-average
molecular weight, Mv
involves a count of the number
of molecules of each species, NiMi
, summed over i, divided by the total
number of molecules
The number-average molecular weight, Mn
If all species in a polymer sample have the same molecular weight (that
is, the polymer is
monodisperse
commonly used
as a simple measure of the polydispersity of the polymer sample
Mw/Mn polydispersity index (PDI)
Determination of
Molecular Weight
- end group analysis
- measurement of colligative properties
- light scattering
- Ultracentrifugation
- dilute solution viscosity
- gel permeation chromatography (GPC)
chemical method use for calculating the numberaverage molecular weight of polymer samples whose molecules contain
reactive functional groups at one end or both ends of the molecule.
end-group analysis
end-group analysis is limited to the determination of polymers with a molecular
weight of
less than about 20,000
methods of analysis under end-group analysis
✓Titrimetric method
✓Nuclear magnetic resonance (NMR)
✓mass spectrometry
✓vibrational spectrometry, like infrared and raman spectroscopy
Properties of solutions that depend on the number of molecules present
and not on the kind of molecules are called
colligative properties.
colligative properties include
boiling point elevation, freezing point depression,
and osmotic pressure.
Boiling point of the solution is __________ than
the pure solvent.
higher
the boiling point of a
solution of known concentration is compared
to that of the solvent at the same pressure
Ebulliometry (Boiling Point Elevation
It works by analyzing the melting behavior of a
substance as it is frozen. By measuring the time it
takes for a specific substance to melt at a certain
temperature, its molecular weight can be calculated.
Cryoscopy (Freezing Point Depression)
most important among
all colligative properties for the determination of
molecular weights of synthetic polymers
osmotic pressure
technique for the
determination of molecular masses of polymers
by means of osmosis.
Membrane osmometry
Membrane osmometry is useful to determine
Mn about
20,000-30,000 g/mol and less than
500,000 g/mol
important
technique for the determination of weight-average molecular weight, M
Light-Scattering
Method
absolute method of molecular weight
measurement
Light-Scattering Method
When polarizable particles are placed in the oscillating electric field of a
beam of light, the ____________ occurs
light scattering
The intensity of scattered light relies on the
concentration, size and polarizability
technique that measures the
intensity of the scattered light to obtain the average
molecular weight Mw of a macromolecule like a polymer or a
protein in solution.
Static light scattering
The scattering intensity of the laser beam is then measured
at a fixed angle
90 degrees
measure of the opposing force of material to
flow
viscosity
gives the relationship between viscosity and
average molecular weight:
Mark-Houwink equation
most common type of
viscometer that is used for the
determination of viscosity of polymer
solution
Ubbelohde
viscometer
extremely powerful method for determining the
complete molecular weight distribution and
average molecular weights
Gel permeation chromatography (GPC)
used to purify and characterize
low-molecular-weight polymers
Ultracentrifuges
The ultracentrifuge is operated at extremely high
speeds up to
70000 rpm
microscale property that is
largely dictated by the amorphous or crystalline portions
of the polymer chains and their influence on each other
Polymer morpholog
CHEMICAL
ANALYSIS OF
POLYMERS
- Mass Spectrometry
- Gas Chromatography
The
polymer is allowed to react to form low-molecular-weight fragments that are
condensed at liquid-air temperature
Mass Spectrometry
an ionization
technique that uses a laser energy-absorbing matrix to
create ions from large molecules with minimal
fragmentatioN
matrix-assisted laser
desorption/ionization (MALDI)
a method of separation in
which gaseous or vaporized components are
distributed between a moving gas phase and fixed
liquid phase or solid adsorbent.
Gas Chromatography
t is an analytical technique used to separate the
chemical components of a sample mixture and then
detect them to determine their presence or absence.
Gas Chromatography
analytical method that combines the features
of gas-chromatography and mass spectrometry to
identify different substances within a test sample
Gas chromatography–mass spectrometry (GC–MS)
SPECTROSCOPIC METHODS
- Infrared Spectroscopy
- Nuclear Magnetic Resonance
(NMR) spectroscopy - Electron Paramagnetic
Resonance Spectroscopy - Ultraviolet–visible
spectroscopy - Raman spectroscopy
analysis
of infrared light interacting with a
molecule. This can be analyzed in
three ways by measuring absorption,
emission and reflection.
Infrared Spectroscopy
non-destructive analytical technique that
measures the absorption or transmission of
infrared radiation by a sample as a function of
frequency or wavelength.
Fourier transform infrared spectroscopy (FTIR)
reliable and cost-effective analytical tool
for identification of polymers and assessment
of the quality of plastic materials
Fourier transform infrared spectroscopy (FTIR)
powerful analytical technique used to study the molecular
structure, dynamics, and composition of organic and inorganic
compounds.
Nuclear Magnetic Resonance (NMR) spectroscopy
The major use of___________ lies in the detection of free radicals
Electron Paramagnetic
Resonance Spectroscopy
works by measuring the presence of paramagnetic ions or molecules with unpaired electrons,
and by observing the resonant absorption of microwaves within a static magnetic field
Electron Paramagnetic
Resonance Spectroscopy
valuable technique for analyzing
polymers, providing insights into their electronic structure,
composition, and molecular interactions.
UV-Vis spectroscopy
powerful qualitative and
quantitative tool with some particular advantages for the
analysis of polymers
Raman spectroscopy
analytical technique used to
study molecular vibrations in materials by measuring the
scattering of light when it interacts with a sample
Raman spectroscopy
Nondestructive
technique that provides detailed information about the
crystallographic structure, chemical composition, and
physical properties of a material
X-Ray diffraction analysis (XRD)
go-to tool for
identifying the type and crystallinity of polymer materials
X-Ray diffraction analysis (XRD)
MICROSCOPY
1, Light
2. Electron
valuable for examining the
texture of solid opaque
polymers
Light Microscopy
technique used to observe the
orientation of molecules in a sample under a microscope. It is
often used with polymers to study their structure, as the
orientation of the polymer chains can reveal information about
their molecular organization.
Polarized light microscopy
type of
microscopy that uses interference patterns
produced by the incoherent light scattered by
specimens to create an image.
Phase-contrast microscopy
t is commonly used in materials science and
polymer science to observe changes in the
morphology of polymers during phase
transitions or in response to external stimuli.
Phase-contrast microscopy
powerful tool in the
study of the morphology of crystalline polymer
Electron Microscopy
beam of
electrons and their wave-like characteristics to
magnify an object’s image, unlike the optical
microscope that uses visible light to magnify
images
electron microscope
type of electron microscope that produces
images of a sample by scanning the surface
with a focused beam of electrons
scanning electron microscope (SEM)
type of electron microscope that transmits
electrons through a thin sample, resulting in an
image of the sample’s interior structure at the
atomic level.
transmission electron microscope (TEM)
THERMAL ANALYSIS
- Differential Scanning Calorimetry
- Differential Thermal Analysis
- Thermogravimetric
Analysis - Thermomechanical
Analysis
thermoanalytical technique in which the difference in
the amount of heat required to increase the
temperature of a sample and reference is measured
as a function of temperature
Differential Scanning Calorimetry
used widely for examining polymeric materials
to determine their thermal transitions.
Differential Scanning Calorimetry
mportant
thermal transitions include the
glass transition temperature (Tg),
crystallization temperature (Tc),
and melting temperature (Tm)
the material under study and an inert reference
are made to undergo identical thermal cycles, (i.e.,
same cooling or heating programme) while recording
any temperature difference between sample and
reference
Differential Thermal Analysis
sensitive balance is used to follow the
weight change of the sample as a function of
temperature
Thermogravimetric
Analysis
measures the mechanical
response of a polymer system
as the temperature is changed.
Thermomechanical
Analysis
MECHANICAL
PROPERTIES
a. Stress-Strain
Properties in
Tension
b. Fatigue Tests
c. Impact Tests
d. Tear
Resistance
e. Hardness
f. Abrasion
Resistance
sually
takes the form of a scratch test, in which
the material is subjected to many
scratches, usually from contact with an
abrasive wheel or a stream of falling
abrasive material.
Abrasion
Resistance
composite property
combining concepts of resistance to
penetration, scratching, marring, and
so on
Hardness
When plastics are used as films,
particularly in packaging applications,
their resistance to
tearing
measure the ability of a
material to resist deformation in response
to a sudden load.
Impact tests
Four commonly used types of impact tests
include
Charpy, Izod, drop-weight, and
dynamic tear tests.
When subjected to cyclic mechanical
stresses, most materials fail at a stress
considerably lower than that required to
cause rupture in a single stress cycle. This
phenomenon is called
Fatigue
performed to measure the
reduction in stiffness and strength of
materials under repeated loading and to
determine the total number of load cycles to
failure.
fatigue tests
he maximum
stress that a material can withstand
while being stretched or pulled
before breaking.
Tensile strength
material property
and is the stress corresponding to
the yield point at which the material
begins to deform plastically.
Yield strength
mechanical property of solid
materials that measures the tensile
or compressive stiffness when the
force is applied lengthwise
Young’s modulus (or Young modulus)
THERMAL
PROPERTIES
a. Softening
Temperature
b. Flammability
usually tested
as the burning rate of a specified
sample.
Flammability
defined as the
temperature at which the resin flows under a
given load on heating.
Softening
Temperature
OPTICAL
PROPERTIES
a. Transmittance and Reflectance
b. Color
c. Gloss
d. Haze
e. Transparency
defined as the state permitting perception of objects through or
beyond the specimen
Transparency
degree of clarity or opacity, or how much
they allow light to pass through them.
Transparency
that percentage of transmitted
light that in passing through the
specimen deviates from the
incident beam by forwar
haze
In commercial hazemeters only
light deviating more than __________
from the transmitted beam
direction is considered haze.
2.5o
geometrically selective
reflectance of a surface responsible
for its shiny or lustrous appearance.
gloss
subjective sensation in
the brain resulting from the
perception of those aspects of the
appearance of objects that result
from the spectral composition of the
light reaching the eye
color
one that transmit part and reflects part of the
light incident on it.
translucent
the ratio of the intensities of light passing through and light
incident on the specimen
transmittance
ELECTRICAL
PROPERTIES
a. Resistivity
b. Dielectric
Constant
c. Dielectric
Strength
d. Arc Resistance
ability of the plastic material to resist
the action of a high voltage electrical arc and resist the
formation of a conducting path along its surface under a
given time.
Arc resistance
material is a
measure of its ability to sustain high-voltage
differences without current breakdown.
dielectric strength
measure of a
material’s ability to store electric charge.
dielectric constant
ability of a polymer material to resist the flow of electrical current.
resistivity
CHEMICAL
PROPERTIES
a. Resistance to Solvent
b. Vapor Permeability
c. Weathering
refers to the process of
degradation of polymers, or large molecules, due to
exposure to external factors such as sunlight,
temperature, and chemicals.
weathering
product of the solubility of the gas or vapor
in the polymer and its diffusion coefficient.
Vapor Permeability
directly measured as the rate of transfer of vapor through unit thickness of the
polymer in film form, per unit area and pressure difference across the film
Permeability
ability of a polymer material to allow certain gases or vapors to
pass through it.
Vapor permeability
he effects of solvents on polymers may take several forms:
Solubility;swelling; environmental stress
cracking,;crazing
which the specimen fails by breaking when exposed to
mechanical stress in the presence of an organic liquid of an aqueous
solution of a soap or other wetting agent
environmental stress
cracking
in which a
specimen fails by the development of a multitude of very small cracks
in the presence of an organic liquid or its vapor, with or without the
presence of mechanical stress.
crazing
