High heat resistance is ULTEM™ resin’s signature property. But there’s a lot to understand about short- and long-term temperature performance—and how it applies to different industries and applications. For a short tutorial on glass transition temperature (Tg), continuous use temperature (CUT), heat deflection temperature (HDT) and relative thermal index (RTI), check out this #SABIC presentation. You’ll learn why #ULTEM resin can take the heat—while retaining strength and stiffness.

1. 1
ULTEM resin has excellent resistance to short and long term heat exposure and is therefore a candidate material for applications
where high heat meets strength and stiffness requirements for improved mechanical and dimensional performance.
What technical parameters do we usually look at when reviewing heat resistance?
ULTEM™ RESIN – TAKING THE HEAT
Tg: Measure of the glass transition temperature when the amorphous/glassy fraction of a
polymer starts to soften.
Tm: Measure of the melt temperature where a crystalline fraction of a polymer starts to melt.
CUT (Continuous Use Temperature): Measure of the highest temperature at which materials
can be used continuously for an extended period without significant problems such as
oxidation, chemical change, excessive creep, loss of strength or other primary properties
for which the material is normally used.
Vicat and HDT (Heat Deflection Temperature): Measure of the temperature at which the test
bars reach certain deformation under load.
RTI (Relative Thermal Index): Measure of the temperature at which 50% of electrical, tensile or
impact strength properties remain to give a long term temperature rating according to
UL746B for electrical equipment.

2. 2
MATERIAL BEHAVIOR OVER A TEMPERATURE RANGE
Tg Stiff Flow
Rubbery
No Flow
Some CrystalsTg
Solid, Locked
Entanglements
Solid, Some Ordered
Chain Structure
Easier Flow
Easier Flow
Tm
Raise Temperature of Polymer
• Tg = Glass transition temperature, the amorphous/glassy fraction starts to soften
• Tm = Melting Temperature of the crystalline fraction of a polymer
10
100
1000
10000
50 100 150 200 250 300
Temperature [ºC]
Modulus[MPa](stiffness)
ULTEM
resin
PPS
EXTEM
resin
DMA Curves for Unfilled Resins
Tg
Tg
Tm
Tg
The typical behavior of materials changes as the temperature increases. The glass transition temperature (Tg) is the temperature
range where a thermoplastic changes from a hard, rigid state to a more stiff flow and rubbery consistency. This is not to be
confused with the melting temperature (Tm) of a crystalline fraction of a polymer.
On the right, you see the dynamic mechanical analysis (DMA), comparison for amorphous ULTEM™ and EXTEM™ resins
compared to a semi-crystalline PPS.

3. 3
0
200
300
Temperature[°C]
Application Lifetime [h]
USE TEMPERATURES
100
AUTOMOTIVE:
Under-the-hood
Application
ELECTRONICS:
Bobbins
HEALTHCARE:
Sterilization Tray
Peak Temperature
CUT Temperature
Short term
In use term
23
To understand heat performance, it is important to
know that not all temperature exposures are the
same. ULTEM™ resin is meeting requirements in
several industries and applications.
For example, healthcare sterilization requirements
expose trays to 134ºC for ten to twenty minutes for
up to 1000 cycles.
In contrast, the continuous use temperature for
electrical bobbins can be at 135ºC for twenty
thousand hours.
A typical automotive under-the-hood application with
a continuous use temperature of 120ºC for three
thousand hours can have peak exposures of up to
150ºC for 500 hours.
Heat performance criteria and requirements may be
industry specific.

4. 4
HEAT DEFLECTION (HDT)
Heat Deflection Temp (HDT) ISO, 1.8MPa
190
200
220
195
179
201
127
141 138
75
104
210 215 212
186
216
147
316
265
210
255
0
50
100
150
200
250
300
350
UNFILLED 30% GF
Heat deflection temperature is a short
term heat – load resistance test. These
tests are depending on conditions such
as load, span and shape of the tested
part.
In amorphous materials, such as ULTEM™
and EXTEM™ resins, glass fillers give a
small raise in HDT.
In semi-crystalline materials, glass fiber
gives a big jump in HDT.
ULTEM resin, being amorphous, provides
a high performance versus unreinforced
semi crystalline solutions.
Semi-crystalline solutions provide a high
HDT when reinforced. Please bear in mind
that this performance is stress and time
dependent (creep) where amorphous
materials are less sensitive to this.

5. 5
RELATIVE THERMAL INDEX (RTI)
Relative Thermal Index, RTI (UL746B): The Relative Thermal Index is a long-term
temperature rating for electrical
equipment and is defined by the UL 746 B
standard.
It defines the temperature at which, after
10 years of exposure, the material has
lost 50% of its performance, such as
tensile strength.
This is an accelerated test with data
collected for about 1 year before the final
results are extrapolated.
ULTEM™ resins perform very well under
long-term heat aging and may
outperform semi-crystalline solutions like
polyamides and amorphous solutions
like polycarbonates and polysulphones.
170
180
155
130
200
130
140
105
180
190
160
130
200 200
120
140
120
0
20
40
60
80
100
120
140
160
180
200
PEI PES PSU PC PEEK PPS PAA PA4,6 sPS
UNFILLED 30% GF

6. 6
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