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- TRƯỜNG ĐẠI HỌC BÁCH KHOA ĐÀ NẴNG
KHOA HOÁ
♣♣♣
PHÂN TÍCH POLYME
(POLYMER ANALYSIS)
TS. Đoàn Thị Thu Loan
- Polymer analysis
üIs a branch of polymer science dealing with analysis and characterisation of
polymers.
üThe complication of macromolecular chains, the dispersion in molecular
weight, tacticity, crystallinity, orientation, composition of polymers etc. and
complex morphological systems
⇒ analysis of polymer ≠ the small organic materials
⇒ Focus on viscoelastic properties, dynamic mechanical testing.
- Methods of polymer analysis
Chemical, Molecular and Structural Surface Mechanical and Physical
Characterisation Characterisation Properties
-Molecular weight determination, -Surface roughness, -Tensile, flexural, impact,
-Microstructural characterisation and -Chemical compression, hardness tests,
compositional analysis, composition, -Rheological and viscoelastic
-Crystallinity, -Interface properties, stiffness and
-Investigation of polymer morphology, modulus, surface tension,
characetrisation
particle size, permeation and diffusion in
-Contact angle and wettability polymers, adhesion tests,
measurements density
Instruments
-AFM, SEM
FT-IR Instron mechanical tester
• •
•
IR-microscope -FT-IR Vicker hardness tester
• • •
GPC ( size exclusion chromatography -Pull-out test DMA
• • •
SEC) Melt flow indexer
•
-Viscosimetry Torsions Rheometer
• •
-X-ray (WAXS and SAXS)
• •
-EM, SEM, TEM, AFM
•
-Dynamic and static methods for contact
•
angle measurements.
- Methods of polymer analysis
Electrical and Optical
Thermal Behaviour Miscellaneous (hon tap)
Properties
Conductivity, electric -Melting point, glass transition Purity and molecular
current in solution, temperature, free rotation temperature, weight of small
light emitting and -Degradation and stability behaviour of molecules, water content
electromagnetic polymers in organic solvents,
surface tension
properties
measurement, pH
Instruments
Inolab conductivity GC
Thermogravimetric analyser (TGA) •
•
meter pH meter
TGA-FTIR coupled technique
•
HPLC
•
• •
Differential scanning calorimetry (DSC) Karl-Fischer titration
•
•
Modulated differential scanning
•
calorimetry (ADSC)
Dynamic thermomechanical analyser
•
(DMTA)
Dielectric relaxation
•
- Purpose of polymer analysis
-For quality control
-For predicting service performance
-To generate design data
-To investigate failures
Essential to identify the purpose of testing, because the requirements for each
of the purposes are different.
-Complexity
-Precision Balance of these attributes,
-Automated test
-Reproducibility according to the purpose of
-Nondestructive test
-Rapidity the test
-Cost
- Quality Control Tests
üNondestructive methods are advantageous and indeed essential when
100% of the output is being tested.
üThe tests should be simple and inexpensive, and automation will
probably aid the rapidity of testing.
üTests related to product performance are preferred.
- Tests Predicting Product Performance
üThe most important factor is that the tests relate to service conditions
and to aspects of product performance.
üshould not be too complex, although rapidity and cheapness are less
important than was the case with quality control.
üNondestructive tests are not always appropriate when predicting product
performance, as it may be necessary to establish the point at which failure
occurs.
- Tests for Producing Design Data
üUsually test pieces are of a simple shape and a specified size, whereas
the product may be of a different geometry and size
üData must be presented in a form that enables the designer to allow for
changes in geometry, time scale, etc.. which implies detailed and
comprehensive understanding of material behavior
üIt follows that data of this type are expensive to produce and that results
are unlikely to be obtained with great rapidity.
üHowever, automation may be advantageous, particularly in the case of
tests running for a long time (creep tests)
- Tests for Investigating Failures
üSome understanding of the various mechanisms of failure is necessary before
suitable tests can be chosen.
ü Tests need not be complex but must be relevant
Ex: a simple measurement of product thickness may establish that there has
been a departure from the specified design thickness.
üThe absolute accuracy of the test may not be important, but it is essential that
it be capable of discriminating between the good and the bad product.
- What are our expectations of polymer materials?
Mechanical and Physical Properties
•Excellent Characteristics:
Thermal Behaviour
Electrical and Optical Properties
•Safe to use
Surface and interface Characteristics
•Light weight
•Reliable, durable
•Low cost
•Less adverse environmental impact
•Good resistance to environmental attacks
- Mechanical Testing
of Polymers
- Types of Mechnical Tests
(h)
(i)
Flexural test (d) (e) (f)
Tensile test (a) Impact test (h) (i)
Compression test (b) Shear (g)
- Tensile test
Scope:
üMeasure the force required to break a specimen and the extent to which the
specimen stretches or elongates to that breaking point.
üProduce a stress-strain diagram, which is used to determine tensile modulus.
üThe data is often used to specify a material, to design parts to withstand
application force and as a quality control check of materials.
üSince the physical properties of many materials (especially thermoplastics) can
vary depending on ambient temperature ⇒ test materials at temperatures that
simulate the intended end use environment.
- Tensile test
Specimen Size:
üThe most common specimen for ISO 527 is the ISO 3167 Type 1A
multipurpose specimen.
üASTM D882 uses strips cut from thin sheet or film.
*The multipurpose test specimen:
+150 mm long,
+The center section: 10 mm wide *4 mm thick *80 mm long.
b
W
δ
l
A tensile dog bone specimen
- For the composite samples
Longitudinal test
Transverse test
- Tensile test Test Procedure:
üSpecimens are placed in the
grips and pulled until failure.
üFor ASTM D638, the test
speed is determined by the
material specification.
üFor ISO 527 the test speed
is typically 5 or 50mm/min for
measuring strength and
elongation
+and 1mm/min for measuring
modulus.
ü An extensometer is used to
determine elongation and
Tensile2.wmv tensile modulus.
- Stress –Strain Behavior
Characteristics of stress-strain behavior:
ü Modulus of elasticity (stiffness, elastic •
modulus, Young’s modulus) is the slope of
Stress, σ
σy σF
the stress-strain curve in the elastic region
ü Yield strength (σy) is the stress applied to a
material that just causes permanent
E
deformation
εy εF
0 2%
ü Tensile strength (TS) is defined at the Strain, ε
fracture point and can be lower than the
= δ/l
yield strength
ü Ultimate tensile strength is the stress that
corresponds to the maximum load
ü Elongation at break (%ε) – the increase in
length of a specimen under tension before P= Applied load
A = Original cross-sectional area
it breaks (Strain).
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