Dynamic Mechanical Analysis (DMA)
Basics and Beyond
ε∗ ω= Σ(Δεβ/1+ιωτβ)
Dr. Lin Li
Thermal Analysis
PerkinElmer Inc.
April 2000
The DMA lets you relate:
product properties
molecular structure
Material
Behavior
processing conditions
DMA Structure in general
How the DMA works:
 Constant inputs and outputs
function as in the TMA
Force Motor
Coil
Magnet
 A sine wave current is added
to the force coil
Temperature Enclosure
 The resultant sine wave
voltage of the LVDT is
compared to the sine wave
force
 The amplitude of the LVDT is
related to the storage modulus,
E' via the spring constant, k.
 The phase lag, δ, is related to
the E" via the damping
constant, D.
LVDT
Core Rod
Interchangeable
Measuring System
Furnace
Heat Sink/Cooling System
Outstanding Flexibility 1:
Multiple Geometries
Compressive
Shear
Extension
Cup & Plate
Flexure
Parallel Plate
Cup & Plate
Tray & Plate
Sintered Plates
3 pt. Bending
4 pt. Bending
AST M Flexure
Dual Cantilever
Single Cantilever
Extension
Shear Sandwich
Coaxial Cylinder
Paper Fold
Log E’
Why?
12
11
10
9
8
7
6
5
4
3
20 mm
1 mm
5 mm
20 mm
Stress Causes Strain...
Lo
L
L-Lo = ΔL
Cauchy or
Engineering Strain
ε = ΔL/Lo
Henchy or
True Strain
ε = ln (ΔL/Lo)
Kinetic Theory
of Rubber Strain
ε = 1/3{L/Lo-(Lo/L)2}
Kirchhoff Strain
ε = 1/2{ (L/Lo)2-1}
Murnaghan Strain
ε = 1/2{1-(Lo/L)2}
The different definitions of tensile strain
become equivalent at very small deformations.
The Elastic Limit: Hooke’s
Law
=
σ
slope = k
Strain increases
with increasing
Stress
ε
Real vs... Hookean StressStrain Curves
Curve 1: DMA
Creep Recovery
in Parallel Plate
File info: Drssr90R.2Thu Apr 14 15:16:52 1994
Sample Height:3.359 mmCreep Stress: 2600.0mN
Dresser 90 Durameter
Recovery Stress:
1.0mN
Limiting
Modulus
1.4
1.2
Hookean
Behavior
Stress (Pa x 10
7)
1.0
0.8
σ
0.6
Slope 1642965.02 Pa/%
0.4
0.2
Slope 359171.32 Pa/%
0.0
4.0
TEMP1: 20.0 C
TIME1:
5.3 min
Real behavior
8.0
12.0
Strain (%)
KPM
PERKIN-ELMER
7 Series ThermalAnalysis System
Thu Apr 14 16:34:38 1994
16.0
ε
The Viscous Limit: Newtonian
Behavior
σ
The speed at which the fluid flows
through the holes (the strain rate)
increases with
stress!!!
slope = η
.
γ
Viscosity Effects
τ
.
γ
• Newtonian behavior is linear and the
viscosity is independent of rate.
• Pseudoplastic fluids get thinner as shear
increases.
• Dilatant Fluids increase their viscosity as
shear rates increase.
• Plastic Fluids have a yield point with
pseudoplastic behavior.
• Thixotrophic and rheopectic fluids show
viscosity-time nonlinear behavior. For
example, the former shear thin and then
reform its gel structure.
Polymers are Non-Newtonian
Fluids!!!
• At low shear rates, the
viscosity is controlled by
MW. The material shows
Newtonian behavior
Linear
Dependence • Viscosity shows a linear
on Rate
dependence on rate above
the ηo region.
• At high rates, the material
can no longer shear thin and
Infinite Shear Plateau ~ η
a second plateau is reached.
∞
Log
η
Zero Shear Plateau ~ ηo
Log
.
γ
Analyzing a Stress-Strain
Curve failure (ε , σ )
linear
region
Β
Β
nonlinear region
σ
yield point (εy, σy)
Young’s modulus (E)
E =
ε
σ
dσ
=
ε
dε
L
L
The area under
the curve to this line
is the energy needed
to break the material
Under Continuos Loads: Creep
Recovery
• Applying a constant
load for long times
and removing it from a
sample.
• Allows one to see the
distortion under
constant load and also
how well it recovers.
Creep is a fundamental
engineering test.
Curve 1: DMA
Creep Recovery
in 3 Point Bending
File info: cr_ptfe-5 Wed Jun 29 15:31:18 1988
Sample Height:
3.300 mmCreep Stress: 1.50e+06Pa
PTFE - CREEP/RELAXATION
Recovery Stress: 6.25e+02Pa
# 1 PTFE - CREEP/RELAXATION AT -5C:cr_ptfe-5
Strain (%)
# 2 Force (mN)
2500.0
2250.0
0.0025
2000.0
1750.0
Force (mN)
0.0020
Strain (%)
• Creep is used as a
basic test for design.
• By looking at both
the creep and
recovery parts of the
curve, we can begin
to examine how
polymers relax.
1500.0
1250.0
0.0015
1000.0
750.0
0.0010
500.0
250.0
0.0005
0.0
0.0000
0.0
-250.0
1.0
2.0
3.0
4.0
Time (minutes)
TEMP1: -15.0 C
TIME1:
7.0 min
5.0
6.0
7.0
DMA7 APPLICATIONS LAB
PERKIN-ELMER
7 Series ThermalAnalysis System
Thu Apr 28 20:32:20 1994
Dynamic Stress
Force (dynamic)
Force
F (static)
Time
material response
Stress =FA
Phase angle = δ
Amplitude = k
Stress
Strain =yo/y
Time
Why? Let’s bounce a ball.
E” ~ energy loss in
internal motion
E’ ~ elastic
response
All this is calculated from δ and
k:
• From k, we calculate E’ (storage modulus)
• From δ, we calculate E’’ (loss modulus)
• then:
Tan δ = E”/E’
E* = E’ + iE” = SQRT(E’2 + E”2)
G* = E*/2(1+ν)
η = 3G*/ω
To apply this to materials...
Dyna mic Stress Scan
σ
σο
ε
ο
ε
Since each part of the ramp
has a sine wave stress
associated with it, we get:
tan δ
E*, E’, E”
η
for each data point!!
For example, DSS Curves
Curve 1: DMA
AC Stress Scanin Parallel Plate
File info: Drssr70DssThu Apr 14 16:44:41 1994
Frequency: 1.00 Hz
Stress Rate: 250.0mN/min
Dresser 70 Durameter Tension: 110.000%
Curve 1: DMA
AC Stress Scanin Parallel Plate
File info: Drssr70DssThu Apr 14 16:44:41 1994
Frequency: 1.00 Hz
Stress Rate: 250.0mN/min
Dresser 70 Durameter Tension: 110.000%
5.5
7
)
4.5
7)
4.0
s x 10
3.5
3.0
Viscosity (Pa
6)
Complex Viscosity (Pa s x 10
5.0
4.5
Dynamic Stress (Pa x 10
# 2 Dresser 90 Durameter:Drssr90dss
5.5
5.0
# 1 Dresser 70 Durameter:Drssr70Dss
7
Complex Viscosity (Pas x 10 )
2.5
2.0
1.5
4.0
3.5
3.0
2.5
2.0
1.0
Slope 6297938.16 Pa/%
1.5
0.5
1.0
Slope 1274361.04 Pa/%
0.0
0.2
0.4
0.6
Strain (%)
TEMP1: 10.5 C
TIME1: -1.2 min
0.8
1.0
KPM
PERKIN-ELMER
7 Series ThermalAnalysis System
Thu Apr 14 16:59:58 1994
0.2
0.4
0.6
Strain (%)
TEMP1: 10.5 C
TIME1: -1.2 min
0.8
1.0
KPM
PERKIN-ELMER
7 Series ThermalAnalysis System
Thu Apr 28 20:28:00 1994
• We can heat the material
under minimal load at a
calibrated rate.
• This allows the material
to change with
temperature.
• These changes can be
described in terms of free
volume or relaxation
times.
Free Volume
Now, let’s induce temperature
as a variable.
Thermomechanical Analysis as
a starting Point.
Curve 1: TMAin Penetration
File info: Tgflex
Tue Oct 10 16:21:08 1995
Sample Height:4.180
mmDC Force: 100.0 mN
Tg by flex
# 1 Tg by flex:Tgflex
Penetration (mm)
7.0
6.5
6.0
Onset 106.92 C
5.5
Penetration (mm)
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
50.0
75.0
100.0
Temperature (C)
TEMP1: 30.0 C
TEMP2: 150.0 C
TIME1:
0.0 min
RATE1: 10.0 C/min
125.0
150.0
175.0
PERKIN-ELMER
7 Series Thermal Analysis System
Sun Nov 26 20:10:47 1995
TMA - It’s all free volume.
Curve 1: TMA
in Expansion
File info:
cte
Tue Oct 10 16:46:51 1995
Sample Height:
1.742
mm DC Force: 10.0 mN
cte
# 1 cte :cte
Expansion (mm)
2.10
Free
Volume
2.05
Expansion (mm)
2.00
1.95
1.90
Cx 2.195 x 10
-2
/C
1.85
1.80
Tg
1.75
Cx 2.948 x 10
1.70
70.0
80.0
-5
Onset 105.53
/C
90.0
Temperature (
TEMP1: 30.0 C
TEMP2: 150.0 C
TIME1:
0.0 min
RATE1: 10.0 C/min
100.0
C)
C
110.0
PERKIN-ELMER
7 Series Thermal
Analysis System
Sun Nov 26 20:08:09 1995
Occupied
Volume
And it’s not just Tg.
Curve 1: TMA
in Extension
File info:
menard005 Tue Feb 21 12:28:20 1995
Sample Height:
12.017
mm DC Force: 0.0 mN
FIBER E
# 1 FIBER E:menard005
Extension (mm)
12.20
12.18
12.16
12.14
Extension (mm)
12.12
12.10
12.08
12.06
12.04
12.02
12.00
11.98
0.0
50.0
100.0
He/20psi/H/Chiller
TEMP1: 30.0 C
TEMP2: 250.0 C
TIME1:
Temperature (
0.0 min
RATE1:
5.0 C/min
150.0
C)
200.0
250.0
Tech.Support Lab/K.Menard
PERKIN-ELMER
7 Series Thermal
Analysis System
Tue Feb 21 12:29:39 1995
(the traditional way to do heat set)
Time Temperature Scans at a
Fixed Frequency
• hold frequency constant and vary
temperature or time at temperature
• allows detection of transitions in material
• allows one to study cures
• most sensitive method for finding Tg
• can also get changes in dimension (TMA)
while collecting DMA data
• Best probe of polymer relaxations as function
of temperature
Idealized Multi-Event DMA Scan
(6)
γ (5)
Β (4)
Tg - glass transition (3) α
E’
Rubbery Plateau (2)
Tm - melting (1)
(6)
(5)
local
bend
motions and
stretch
Temperature
(4)
(3)
side
gradual
groups main
chain
(2)
large
scale
chain
(1)
chain
slippage
Log Modulus (Pa)
In more detail...
11
10
9
8
7
6
5
4
3
F
E
Crystalline Polymer
D
C
Crystal-crystal slip
B
Glassy
Cross-linked
A
Rubbery
Temperature
F
E
D
C
B
A
Deformation
Secondary
Dispersion
Hookean
Behavior
Second
Transition
Primary
Transition
Highly Visco Elastic
Flow
(alpha)
(rubbery)
(melt)
Molecular
Motion
Localized
Motion
Bend &
Stretch
Bonds
Side
Groups
Main
Chain
Gradual
Main Chain Large
Scale Mobility
Chain
Slipping
(gamma)
(beta)
Unstrained
State
Strained
State
Increasing
R. Seymour, 1971
Common changes show as:
MW
E’
tan δ
MWD
Crosslink Density
Crystallinity
Tg are easily seen, as in PET Film
Temp/Time Scan
demofilm
in Extension
Wed Oct 11 17:06:48 1995
Amplitude: 21.949u
Tension: 110.000%
1.6
#1
pet film:demofilm
tan
#2
Storage Modulus (Pa x 10
9
)
tan
3.0
1.0
2.5
9
1.2
0.8
Onset 83.29
C
2.0
0.6
1.5
0.4
Onset 107.82
0.2
1.0
C
0.5
0.0
Onset 79.35
C
0.0
-100.0
0.0
100.0
Temperature (
TEMP1: -100.0 C
TEMP2: 250.0 C
)
3.5
1.4
TIME1: 0.0 min
RATE1: 10.0 C/min
200.0
C)
PERKIN-ELMER
7 Series Thermal
Sun Nov 26 21:02:11 1995
300.0
Analysis System
Modulus (Pa x 10
Curve 1: DMA
File info:
Frequency: 1.00 Hz
pet film
or in PP fishing line.
Curve 1: DMA Temp/Time Scan in Extension
File info:
1116942
Wed Nov 16 13:20:39 1994
Frequency: 1.00 Hz
Dynamic Stress: 200.0mN
fishing line
Static Stress: 300.0mN
# 1 fishing line:1116942
-1
tan
(x 10
)
# 2 Storage Modulus (Pa x 10
9
)
8.0
2.5
7.0
5.0
1.5
tan
4.0
1.0
Modulus (Pa x 10
(x 10
-1
)
6.0
9
)
2.0
3.0
2.0
0.5
1.0
0.0
0.0
-100.0
-50.0
0.0
50.0
Temperature (
TEMP1: -130.0 C
TEMP2: 270.0 C
TIME1:
0.0 min
RATE1: 10.0 C/min
100.0
C)
150.0
200.0
PERKIN-ELMER
7 Series Thermal
Analysis System
Sun Nov 26 21:24:35 1995
Sample prep can be minimal if only temperatures are needed.
Transitions are clearly seen in
highly crosslinked samples
#1
epoxyresin:afriedli.1
Storage Modulus (Pa x 10
#2
tan
9
)
1.0
4.5
0.9
4.0
0.8
3.5
0.7
3.0
0.6
2.5
0.5
2.0
0.4
1.5
0.3
1.0
0.2
0.5
0.1
0.0
0.0
0.0
50.0
heavy xlink
TEMP1: 30.0 C
TEMP2: 250.0 C
100.0
150.0
Temperature (
TIME1:
0.0 min
C)
RATE1: 10.0 C/min
This Tg is undetectable in the DSC !!!!!!
200.0
km
PERKIN-ELMER
7 Series Thermal
Thu Jun 23 13:45:10 1994
250.0
Analysis System
tan
Modulus (Pa x 10
9
)
Curve 1: DMA
Temp/Time Scan
in 3 Point Bending
File info:
afriedli.1
Thu Feb 17 12:14:11 1994
Frequency: 1.00 Hz
Dynamic Stress: 800.0mN
epoxyresin
Static Stress: 1000.0mN
as well as in blends.
Curve 1: DMA
Temp/Time Scan
in 3 Point Bending
File info:
sbr14
Thu Feb 15 10:45:19 1990
Frequency: 1.00 Hz
Dynamic Stress: 2.00e+05Pa
STYRENE BUTADIENE RUBBE
Tension: 110.000%
#1
STYRENE BUTADIENE RUBBER:sbr14
Storage Modulus (Pa) L
#2
tan
1.0
0.9
10 9
0.8
0.6
10 8
0.5
0.4
0.3
10 7
0.2
0.1
10 6
-150.0
0.0
-100.0
-50.0
K66:22T914
TEMP1: -180.0 C
TEMP2: 250.0 C
0.0
Temperature (
TIME1:
0.0 min
RATE1:
5.0 C/min
50.0
C)
100.0
150.0
APPLICATION LABORATORY
PERKIN-ELMER
7 Series Thermal
Analysis System
Sun Nov 26 20:54:43 1995
200.0
tan
Modulus (Pa)
0.7
It’s not always so simple:
For example, crystal-crystals slips can cause α∗ transitions
Curve 1: DMA
Temp/Time Scan
in 3 Point Bending
File info:
AMPfrPP.1
Wed Oct 27 13:49:06 1993
Frequency: 1.00 Hz
Dynamic Stress: 950.0mN
LeBrun samples
Static Stress: 1000.0mN
#1
#2
LeBrun samples:AMPfrPP.1
Storage Modulus (Pa x 10
tan
(x 10
-1
9
)
)
3.0
Modulus (Pa x 10
Tg or
Alpha
1.0
1.0
Tα*
0.5
-150.0
TEMP1: -160.0 C
TEMP2: 300.0 C
0.5
0.0
-100.0
-50.0
AMP Flame Retardant Polypropylene
TIME1:
0.0 min
0.0
Temperature (
RATE1:
5.0 C/min
-1
tan
1.5
1.5
(x 10
9
)
2.0
2.0
)
2.5
2.5
50.0
C)
KPM
PERKIN-ELMER
7 Series Thermal
Sun Nov 26 20:58:36 1995
100.0
Analysis System
Higher Order Transitions
affect toughness
Curve 1: DMA
Temp/Time Scan
in 3 Point Bending
File info:
AMP66gp.1
Tue Oct 26 16:05:29 1993
Frequency: 1.00 Hz
Dynamic Stress: 190.0mN
LeBrun samples
Static Stress: 200.0mN
LeBrun samples
4.0
5.5
5.0
3.5
4.5
Good Impact Strength
)
3.0
Modulus (Pa x 10
3.0
2.5
β Transitions
2.0
Poor
1.5
1.5
Tg
2.0
1.0
1.0
0.5
0.5
0.0
0.0
-150.0
-100.0
-50.0
AMP good part 20% glass filled Nylon 6/6
TEMP1: -160.0 C
TEMP2: 300.0 C
TIME1:
0.0 min
0.0
Temperature (
RATE1:
5.0 C/min
Impact was good if Tg/Tβ was 3 or less.
50.0
C)
100.0
KPM
PERKIN-ELMER
7 Series Thermal
Sat Oct 15 14:32:54 1994
150.0
Analysis System
(x 10
2.5
3.5
tan
9
-1
)
4.0
...and also define operating
range.
Curve 1: DMA Temp/Time Scan in 3 Point Bending
File info:
gamma_1
Thu Jun 30 02:17:24 1988
Frequency: 7.00 Hz
Dynamic Stress: 1.86e+06Pa
EPOXY PC BOARD AT 7 Hz
Static Stress: 1.86e+06Pa
# 1 EPOXY PC BOARD AT 7 Hz:gamma_1
10
Storage Modulus (Pa x 10
)
1.1
-> # 2
tan
-1
(x 10
)
Beta
5.0
4.5
Tg
0.8
4.0
3.0
Operating
range
0.6
0.5
0.4
2.5
2.0
1.5
0.3
1.0
0.2
0.5
0.1
0.0
0.0
-100.0
0.0
Temperature (
TEMP1: -180.0 C
TEMP2: 300.0 C
TIME1:
0.0 min
RATE1: 10.0 C/min
100.0
C)
200.0
PE DMA7 R&D LAB
PERKIN-ELMER
7 Series Thermal
Analysis System
Sun Nov 26 20:13:53 1995
(x 10
0.7
tan
Modulus (Pa x 10
10
)
3.5
)
0.9
-1
1.0
It can get complex...
Curve 1: DMA
Temp/Time Scan
in Extension
File info:
T2n4ptg
Fri Jan 18 18:14:51 1991
Frequency: 1.00 Hz
Dynamic Stress: 1.00e+07Pa
NYLON MONOFILAMENT
Static Stress: 1.05e+07Pa
2
#1
NYLON MONOFILAMENT:T2n4ptg
Storage Modulus (Pa) L
#2
tan
(x 10
-1
4.0
)
3.5
-1
)
3.0
(x 10
2.5
4
3
2.0
2
1.5
Tg or Tα
10 9
9
8
7
6
5
-200.0
Tγ
-150.0
iNITIAL RUN
TEMP1: -180.0 C
TEMP2: 0.0 C
TEMP3: 150.0 C
TIME1: 0.0 min
TIME2: 0.0 min
-100.0
Tβ
Stress
Relief
-50.0
0.5
0.0
0.0
Temperature (
RATE1: 4.0 C/min
RATE2: 2.0 C/min
1.0
50.0
C)
100.0
B.Cassel
PERKIN-ELMER
7 Series Thermal
Sun Nov 26 20:59:14 1995
150.0
Analysis System
200.0
tan
Modulus (Pa)
10 10
9
8
7
6
5
Curing of Thermosets
• can be studied at constant temperature or by a
temperature ramp
• can get minimum viscosity, gelation point (time),
vitrification point, and activation energies from
DMA curve
• can adapt instrument to do simultaneous DEADMA to follow cure to completion
• cure studies are not limited to polymeric systems
but include food products like cakes and cookies
Analysis of a Cure by DMA
10 8
10 7
Modulus
10 6
E’-E” Crossover ~ gelation point
106 Pa ~ Solidity
10 5
vitrification point
E”
10 4
Curing
10 3
E’
10 2
Melting
10 1
Minimum Viscosity (time, length,
temperature )
η∗
10 0
50.0
70.0
90.0
Τ
110.0
130.0
150.0
QC can often be done by
simply fingerprinting the resin.
3.5
3.0
note the different slopes and
the different curve shapes
2.5
η∗
2.0
1.5
bad
1.0
0.5
good
0.0
25.0
50.0
75.0
100.0
125.0
150.0
Postcure studies allow process
optimization:
1.0
Postcure time vs... Tg and E’
1 hour
0 hours
2 hours
200
180
3 - 8 hours
160
140
120
tan δ
Property
0.5
100
E'@50 ( E 9 P A )
80
60
E' ONSET
40
T A N D PE A K
20
0.0
T A N D ONSET
0
150
200
175
Temperature
0
2
4
TIME IN HOURS
6
8
Frequency Scans
•
•
•
•
•
hold temperature constant and vary frequency
allows one to look at trends in material
can estimate changes in MW and MWD
looks at both tack-like and peel-like behavior
can use data for Time Temperature Superposition
to extend frequency range or predict age life.
Frequency determines the type
of response
10 7
More
Liquid
like
More
solid
like
10 6
10 5
10 5
10 4
10 4
Flow dominates
Elastic dominates
10 3
10 3
10 -2
10 -1
10 0
Frequency (Hz)
10 1
Viscosity (Pa
Modulus (Pa)
s)
10 6
10 7
For example, two hot melt adhesives...
show affect of rate (peel vs.... tack)
η∗
10 8
10 8
10 7
10 7
bad
10 6
10 6
10 5
10 5
10 4
10 4
good
10 3
10 2
10 3
10 -4
10 -3
10 -2
10 -1
Τ
10 0
10 1
10 2
E’’
Creep can look at distortion
under load,
Curve 1: DMA
Creep Recovery
in 3 Point Bending
File info:
cr_ptfe-5
Wed Jun 29 15:31:18 1988
Sample Height:
3.300
mm
Creep Stress: 1.50e+06Pa
PTFE - CREEP/RELAXATION
Recovery Stress: 6.25e+02Pa
#1
PTFE - CREEP/RELAXATION AT -5C:cr_ptfe-5
Strain (%)
#2
Force (mN)
2500.0
2250.0
0.0025
2000.0
Strain (%)
1500.0
1250.0
0.0015
1000.0
750.0
0.0010
500.0
250.0
0.0005
0.0
-250.0
0.0000
0.0
1.0
2.0
3.0
Time (minutes)
TEMP1: -15.0 C
TIME1: 7.0 min
4.0
5.0
6.0
DMA7 APPLICATIONS LAB
PERKIN-ELMER
7 Series Thermal
Analysis System
Thu Apr 28 20:32:20 1994
7.0
Force (mN)
1750.0
0.0020
cyclic application of loads,
Differences can be seen in good and bad samples and get more apparent with
several cycles. Here the bad material is not flowing enough to fill the pores and
form a mechanical bond.
55.0
50.0
Good
% Strain
45.0
40.0
35.0
30.0
25.0
20.0
15.0
10.0
Bad
5.0
0.0
6.0
0.0
1.0
2.0
3.0
Time in minutes
4.0
5.0
and with varying temperatures.
Curve 1: DMA
Creep Recovery
in Parallel Plate
File info:
DR90D2.1
Fri Jul 23 12:23:50 1993
Sample Height:
2.836 mm Creep Stress: 2600.0mN
Dresser 90 D
Recovery Stress: 1.0mN
# 1 Dresser 90 D:DR90D2.1
Strain (%)
#2
Force (mN)
#3
T ( C)
P
2750.0
22.0
2500.0
20.0
2250.0
18.0
2000.0
16.0
1750.0
14.0
1500.0
12.0
1250.0
10.0
1000.0
8.0
750.0
6.0
500.0
250.0
4.0
0.0
2.0
-250.0
0.0
0.0
25.0
50.0
75.0
Time (minutes)
TEMP1: -50.0 C
TEMP2: 0.0 C
TEMP3: 50.0 C
TEMP4: 100.0 C
TIME1:
TIME2:
TIME3:
TIME4:
11.0
15.0
15.0
75.0
min
min
min
min
RATE1: 10.0 C/min
RATE2: 10.0 C/min
RATE3: 10.0 C/min
100.0
125.0
KPM
PERKIN-ELMER
7 Series Thermal
Analysis System
Sun Nov 26 20:41:31 1995
Force (mN)
Strain (%)
24.0
And you can tabulate this stuff
graphically...
τ
1/T
• The time to 1/e
percent recovery is
the relaxation.
• This is a measure
of how quickly a
material recovers.
(There is a lot more
to this subject.)
Stress Relaxation
Experiment Starts
Position
• By exploiting the special
controls of the DMA-7e,
we can run stress
relaxation experiments.
• These look at how the
force change for a
sample kept at a set
distortion as a function of
time or temperature.
σ
Time
Sample would be distorted to y length and held.
Don’t forget the DMA-7e also does
Stress Scans
• can do either static or dynamic ramps
• static scans calculate Young’s modulus and
stress-strain curves
• dynamic scans give material response to
increasing oscillatory forces:
– get complex viscosity and modulus for each data point
– can look at changes in elasticity (E’) and lag (phase angle) with
increasing stress
• Both methods are fast tests for QC applications
after the material has been fully characterized by
other DMA modes.
Specialized Testing is Possible...
The design of the DMA-7e makes it possible to
do:
Time-Temperature Superposition (TTS)
DEA/DMA
Tests in Solution
Microscopic DMA
Photo DMA
DMA-?
PP fibers in solvent
200.0
175.0
Force in mN
150.0
air
125.0
xylene
100.0
water
75.0
50.0
iso-octane
25.0
0.0
20.0
40.0
60.0
Temperature in C
80.0
100.0
To Review, DMA ties together...
m olecular structure
Molecular weight
MW Distribution
Chain Branching
Cross linking
Entanglements
Phases
Crystallinity
Free Volume
Localized motion
Relaxation Mechanisms
product properties
Material
Behavior
processing conditions
Stress
Strain
Temperature
Heat History
Frequency
Pressure
Heat set
Dimensional Stability
Impact properties
Long term behavior
Environmental resistance
Temperature performance
Adhesion
Tack
Peel
Conclusions
• DMA allows you to preform a wide range of
tests from sensitive probes of molecular
structure to model studies.
• the DMA-7e allows operation as six different
instruments to maximize flexibility.
• Data can be overlayed with DSC, TGA, TMA,
and DTA for easier analysis.
References: Books
•
•
•
•
•
•
•
•
•
•
•
Menard, DMA: Introduction to the Technique, Its Applications and Theory,
CRC Press, 1999.
Brostow et a., Failure of Plastics, Hanser, 1986.
Ferry, Viscoelastic Properties of Polymers, Wiley, 1980.
Gordon et al., Computer Programs for Rheologists, Hanser, 1995.
Gol'dman, Prediction of Deformation Properties of Polymeric and Composite
Materials,, ACS, 1994.
Mascosko, Rheology, VCH, 1993.
Matsouka, Relaxation Phenomena in Polymers, Hanser, 1993.
McCrum et al, Anelastic and Dielectric Properties of Polymeric Solids, Dover,
1992 (reprint of 1967 edition).
Nielsen et al., Mechanical Properties of Polymers and Composites, Dekker,
1994.
Sperling, Introduction to Physical Polymer Science, Academic Press, 1994.
Ward et al., Introduction to Mechanical Properties of Solid Polymers, Wiley,
1993.