ENSACO® Conductive Carbon Black for polymer ... - Timcal Graphite

Graphite
Carbon Black
Carbon additives for
polymer compounds

Who are we?
TIMCAL Graphite & Carbon has a
strong tradition and history in carbon
manufacturing. Its fi rst manufacturing operation
was founded in 1908.
Today, TIMCAL facilities produce and
market a large variety of synthetic and natural
graphite powders, conductive carbon
blacks and dispersions of consistent high
quality.
Adhering to a philosophy of Total Quality
Management and continuous process
improvement, the TIMCAL manufacturing
plants comply with ISO 9001-2000.
TIMCAL Graphite & Carbon is committed
to produce highly specialized graphite
and carbon materials for today and tomorrow
customers’ needs.
TIMCAL Graphite & Carbon is a member
of IMERYS, a world leader in adding
value to minerals.
Where
are we located?
With headquarters in Switzerland,
TIMCAL Graphite & Carbon has an
international presence with facilities and
commercial offi ces located in key markets
around the globe.
The Group’s industrial and commercial
activities are managed by an experienced
multi-national team of more than 450
employees, from many countries on three
continents.
www.timcal.com
Bodio, Switzerland
Willebroek, Belgium
Lac-des-Îles, Canada
Terrebonne, Canada
Changzhou, China
Baoutou, China
Fuji, Japan
About polymer
compounds
Far more is expected from polymers and
their compounds than ever before. Designers
seek to enhance physical and chemical properties
and, at the same time, to slash production
costs. Carbon additives are a key factor in
this development.
Today producers demand starting materials
of outstanding definition and consistency of
properties. Products whose quality is constant
over decades, thus eliminating unpredictable
and undesired side effects.
TIMCAL Graphite & Carbon produces a
variety of synthetic and natural graphite,
conductive carbon black and calcined petroleum
coke with a common keyword: consistency.
They are manufactured under stringent
process control conditions from the
raw material stage through the end product.
This documentation is intended to help our
customers to make the best possible selection
from the wide range of TIMCAL’s carbon
additives available for the use in their polymer
compounds.
TIMCAL Graphite & Carbon puts its
technical experience at the customer's disposal
through its Technological Development
Department.
Our team of experts has extensive knowledge
of application processes as well as an
excellent problem-solving record.
Besides providing customer support, our
Technological Development Department
works with our Marketing Group to find new
applications to meet the growing challenges
facing the industry.
For further information please feel free to
contact our team of experts who are ready to
help you or visit our website: www.timcal.com

TIMREX ® Graphite and
ENSACO ® Carbon Black
Carbon additives for polymer compounds Contents
The products
• Introduction to ENSACO ® Conductive Carbon Black
• Introduction to TIMREX ® Graphite and Coke
• ENSACO ® Conductive Carbon Black for polymer compounds
• TIMREX ® Graphite and Coke for polymer compounds
Typical applications for ENSACO ® Conductive Carbon Black
• Electrically conductive plastics
• Rubber
• Power cables and accessories
Typical applications for TIMREX ® Graphite and Coke
• Self lubricating polymers
• Filled PTFE
• Thermally conductive polymers
• Flame retardant polymers
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3

4
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Introduction to ENSACO ®
Conductive Carbon Black
Conductive carbon blacks are carbon blacks with high to very high void volume allowing
the retention of a carbon network at low to very low filler content. The void volume
can originate from the interstices between the carbon black particles, due to their
complex arrangement, and from the porosity.
100 nm
TEM picture of ENSACO® Carbon Black
showing the high level of aggregation.
By courtesy of University of Louvain (Louvain-La-Neuve)
1 µm
SEM picture of ENSACO® 250 G Carbon Black
illustrating the high void volume.
By courtesy of University of Louvain (Louvain-La-Neuve)
STM picture of the surface of ENSACO® 250 G
Carbon Black 5x5 nm.
By courtesy Prof. Donnet - Mulhouse
100 nm
SEM picture of ENSACO® 250 G Carbon Black
illustrating the high void volume.
By courtesy of University of Louvain (Louvain-La-Neuve)
How ENSACO ®
Conductive Carbon
Blacks are produced
NThe Timcal carbon black process has been
developed around 1980 and is commercially
exploited since 1982. The plant uses most
modern technology. The process is based on
partial oil oxidation of carbochemical and
petrochemical origin. The major difference
with other partial combustion carbon black
technologies lies in the aerodynamic and
thermodynamic conditions:
low velocity;
no quench;
no additives.
NThis leads to a material with no or nearly
no sieve residue on the 325 mesh sieve and
allows the highest possible purity.
NThe granulation process has been developed
to achieve an homogeneously consistent
product maintaining an outstanding dispersibility.
It is in fact a free-flowing flake characterised
by a homogeneous and very low
crushing strength that guarantees the absence
of bigger and harder agglomerates.
The process enables the production of low
surface area conductive carbon blacks as well
as very high surface area conductive carbon
blacks. The low surface area materials show
a chain-like structure comparable to acetylene
black. The very high surface area materials
belong to the Extra Conductive (EC)
family. Although ENSACO ® Carbon Blacks
are slightly more graphitic than furnace
blacks, they are quite close to the latter ones
as far as reinforcement is concerned.
ENSACO ® Carbon Blacks combine to a
certain extent both the properties of furnace
and acetylene black, reaching the optimal
compromise.

Introduction to TIMREX ®
Graphite and Coke
NGraphite finds wide application because
of its favourable combination of properties.
These include:
low friction, chemical inertness
and absence of inherent abrasiveness;
high thermal conductivity, thermal
stability and electrical conductivity;
film forming ability on metal surfaces;
relatively inoffensive nature of both
Npowders and products of combustion.
NThese properties are a consequence of
the lamellar graphite structure and the
anisotropic nature of chemical bonding
between carbon atoms. In graphite, three
sp 2 hybrid orbitals (each containing one
electron) are formed from the 2s and two
of the 2p orbitals of each carbon atom
and participate in covalent bonding with
three surrounding carbon atoms in the
graphite planes. The fourth electron is
located in the remaining 2p orbital,
which projects above and below the
graphite plane, to form part of a polyaromatic
π-system.
SEM picture of TIMREX® Graphite showing
the perfect crystalline structure.
NDelocalisation of electrons in π-electron
system is the cause of graphite's high stability
and electrical conductivity.
Interlamellar bonding was once thought
to be weak and mainly the result of Van der
Waals forces, however, it now appears that
interlamellar bonding is reinforced by πelectron
interactions. Graphite is therefore
not intrinsically a solid lubricant and
requires the presence of adsorbed vapours
to maintain low friction and wear.
How TIMREX ®
Graphite and Coke
powders are produced
TIMREX ®
Primary Synthetic Graphite
TIMREX ® Primary Synthetic Graphite
is produced in a unique highly controlled
graphitization process which
assures narrow specifications and
unequalled consistent quality due to:
monitoring of all production and processing
stages, strict final inspection, and
clearly defined development processes.
TIMREX ® Primary Synthetic Graphite
shows unique properties thanks to the
combination of a consistent purity, perfect
crystalline structure and well defined
texture.
TIMREX ®
Natural Flake Graphite
TIMREX ® Natural Flake Graphite is
produced in a wide range of products distinguished
by particle size distribution,
chemistry and carbon content. Timcal
mines the graphite from its own source in
Lac-des-Îles, Quebec, Canada. Further
processing can be done either in Lac-des-
Îles or for high added value products (e.g.
TIMREX ® PG25) in our new processing
plant in Terrebonne, Quebec, Canada. All
TIMREX ® “Naturals” are thoroughly controlled
in our laboratories to ensure quality,
consistency and total customer satisfaction.
TIMREX ® Coke
TIMREX ® Petroleum Coke is calcined
at appropriate temperature with low ash
and sulphur content, well defined texture
and consistent particle size distribution.
5

6
Typical values
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ENSACO ® Conductive Carbon Black
for polymer compounds
Property Test Method Unit ENSACO 150 G ENSACO 210 G ENSACO 250 G ENSACO 260 G ENSACO 350 G
Form Granules (*) Granules Granules (*) Granules Granules
BET Nitrogen Surface Area
ASTM D3037
OAN
Absorption
ASTM D2414 (1)
COAN Crushed OAN
ASTM D2414 (1)
Pour Density
ASTM D1513
Moisture (as packed)
ASTM D1509
Sieve residue
325 mesh (45 µm)
ASTM D1514
Ash Content
ASTM D1506
Volatile Content
TIMCAL Method 02 (2)
Sulphur Content
ASTM D1619
Toluene Extract
ASTM D4527
pH
ASTM D1512
Volume Resistivity
TIMCAL Method 11 (3) (4)
m2/g
ml/100 g
ml/100 g
kg/m3
%
ppm
%
%
%
%
Ohm.cm
50
165
95
190
0.1
2
0.1
0.2 max
0.5 max
0.1 max
8-11
2000 max (3)
55
155
95
210
0.1
2
0.1
0.2 max
0.5 max
0.1 max
8-11
500 max (3)
65
190
104
170
0.1
2
0.01
0.2 max
0.02
0.1 max
8-11
10 max (3)
70
190
104
170
0.1
2
0.01
0.2 max
0.02
0.1 max
8-11
5 max (3)
(1) Spring: 0.9 lbs/inch; 10 g of carbon black - (2) Weight loss during heating between 105 and 950°C - (3) 25% carbon black in HDPE Finathene 47100
(4) 15% carbon black in HDPE Finathene 47100
(*)ENSACO® 150 and ENSACO® 250 are also available in powder form.
770
320
270
135
1 max
10
0.03
0.3 max
0.02
0.1 max
8-11
20 max (4)

Typical effects on polymer compounds
ENSACO ® Conductive Carbon Black
for polymer compounds
Property ENSACO 150 G ENSACO 210 G ENSACO 250 G ENSACO 260 G ENSACO 350 G
Form Granules (*) Granules Granules (*) Granules Granules
BET Nitrogen Surface Area (m 2 /g)
OAN Oil Absorption (ml/100 g)
Conductivity
Dispersibility
Purity
Water absorption
Surface smoothness
Electrical/Mechanical
properties balance
Resistance to shear
Comments to
application domains
50
165
MRG
(Mechanical Rubber Goods)
55
155
Easy strippable
insulation shields
excellent very good good quite good difficult
(*)ENSACO® 150 and ENSACO® 250 are also available in powder form.
65
190
very low very low very low very low high
70
190
All polymers
770
320
7

8
Typical values
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TIMREX ® Graphite and Coke
for polymer compounds
Synthetic Graphite
T Graphite
KS Graphite
SFG Graphite
Natural Graphite
Particle size range
d90 (µm)
0 25 50 75 150
0 25 50 75 150
0 25 50 75 150
0 25 50 75 150
0 50 100 150
0 50 100 150
0 50 100 150
T 15
T 75
KS 6
KS 15
KS 5-25
KS 44
KS 5-44
KS 150
SFG 6
SFG 44
SFG 150
Ash
(%)
0.08
0.07
0.06
0.05
0.03
0.06
0.02
0.06
0.07
0.07
0.03
PG Graphite 200
Solid content
(%)
0.10 1.17 6.5 27.5

Typical effects on polymer compounds
TIMREX ® Graphite and Coke
for polymer compounds
Synthetic Graphite
T Graphite
Extra Fine
Fine
KS Graphite Extra Fine
Fine
Fine-Special
Coarse
SFG Graphite Extra Fine
Fine
Coarse
Natural Graphite
PG Graphite Extra Fine
Fine
FR Graphite Coarse
Special Graphite
B Graphite BNB90
PC Coke
Flare Graphite
LB Dispersion
PC40
Coarse
LB1300
Thermally conductive
polymer
Thermal
conductivity
4 W/(m.K)
Self
Lubrication
Self lubricating
polymers
Friction
Modification
Wear
Reduction
excellent good quite good neutral negative
*
Creep
resistence
Filled
PTFE
Deformation
under loading
Flame
retardant
Intumescent
effect
Processability
low carbon
loading
high carbon
loading
* in PTFE
9

10
The selection of a
conductive carbon black
NENSACO ® Conductive Carbon Blacks find
their applications in an unlimited number of
plastics. The combination of the polymer type
and grade and the carbon black grade are determining
the overall electrical and mechanical
performance.
NThe main parameter influencing the final
conductivity of a finished part in a given polymer
is the type and level of carbon black used.
NThe higher the structure of the carbon black,
the lower the level of carbon black needed to
achieve the required conductivity. Nevertheless,
in a minor way, other parameters like the additives
in presence, the compounding or processing
conditions may also influence the final conductivity
of parts.
NLow surface area conductive carbon blacks
show a particular advantage on dispersion and
processing.
NPercolation curves – correlating the volume
resistivity and the carbon black percentage – are
a useful comparative tool to predict the conductivity
in place and to select the more appropriate
system. These curves are valid for a given formulation
and sample preparation technique.
NThe selection of the conductive carbon black
will also influence:
the compounding behaviour
(dispersibility, resistance to shear, mixing cycle,
melt flow index, extrusion throughput);
the surface appearance of the finished
material (number of surface defects);
the mechanical properties
(polymer property retention, reinforcement);
the overall price – performance ratio.
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Typical applications for ENSACO ® Conductive Carbon Black
Electrically
conductive plastics
The preparation of a
conductive compound
NSuitable mixing equipments for the preparation
of black conductive compounds include
internal mixers, twin screw extruders, single
screw kneader machines and LCM. The feeding
of low bulk density, soft flake-type carbon
blacks into extruders requires the use of twin
screw feeders and separate introduction on an
already molten polymer (split feeding technology).
Some typical final plastics
applications:
handling of electronic components:
carrier boxes, carrier trays, carrier tapes, etc.;
films: antistatic and conductive films,
packaging films, garbage bags, etc.;
automotive industry: fuel injection systems,
anticorrosion systems, fuel tank inlet,
electrostatically paintable parts, etc.;
transport: mobile phone parts, wheels,
containers, bins, pallets, etc.;
computer: antistatic articles for computer
& accessories, CD player, etc.;
health: medical applications,
cleanroom equipments, articles for
antistatic workplaces, etc.;
antistatic flooring;
heating element;
sensors;
PTC switches;
UV protection and pigmentation.
In the following pages there are some of the
results of experimental work carried out on
ENSACO ® Conductive Carbon Blacks in different
polymer compounds.
The data shown here are given as orientation
and are valid for the particular formulations
and sample preparation technique
mentioned. Results in other polymers, full
studies and publications are available upon
request.

ENSACO ® Conductive Carbon Blacks in HDPE
Volume Resistivity (Ohm.cm)
Volume Resistivity (Ohm.cm)
Volume Resistivity (Ohm.cm)
10 9
10 7
10 5
10 3
10
0.1
0
800
700
600
500
400
300
200
100
0
4
7.0
6.5
6.0
5.5
5.0
4.5
4.0
3.5
3.0
4
Various carbon blacks in HDPE
E 250
E 260
E 350
10 20 30 40 50
% Carbon Black Concentration (%)
Resistivity vs mixing time - 18% carbon black
E 250
E 260
5 6 7 8 9 10
Brabender Mixing Time (min)
Resistivity vs mixing time - 25% carbon black
E 250
E 260
5 6 7 8 9 10
Brabender Mixing Time (min)
Influence of the carbon black type
on the resistivity:
Compounding: laboratory Brabender
internal mixer.
Processing: compression moulding.
The higher the structure of the carbon black, the lower
the percolation threshold.
At a concentration very near to the percolation level,
when overmixed, ENSACO ® 260 G offers a higher
consistency in resistivity resulting from its higher
shear stability in extreme working conditions.
At a concentration far above the percolation level,
both blacks are very stable in resistivity when overmixed.
ENSACO ® 260 G shows a consistent lower
resistivity.
11

12
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ENSACO ® Conductive Carbon Blacks in LDPE
Volume Resistivity (Ohm.cm)
Volume Resistivity (Ohm.cm)
10 8
10 6
10 4
10 2
10 0
10 4
10 3
10 2
10 1
10 0
Various carbon black in LDPE MFI 0.3 and 36 (g/10 min)
E250 G LD 0.3
E250 G LD 36
N472 LD 0.3
N472 LD 36
P-type LD 0.3
P-type LD 36
0 5 10 15 20 25 30 35
Carbon Black Concentration (%)
ENSACO ® Conductive Carbon Blacks in PP
PPH MI54 (230 °C/5 kg) with various conductive carbon blacks
E250 G: high structure - low surface area
N472: high structure - high surface area
1 10
MFI (230 °C/5 kg) (g/10 min)
100
Influence of the carbon black type on the resistivity.
Relation between resistivity and melt flow index:
Compounding and processing: twin screw extruder Haake PTW16 and realization
of tapes.
At same structure level, the carbon black with the lowest surface area has the
smallest impact on fluidity reduction.
Volume Resistivity (Ohm.cm)
10 5
10 4
10 3
10 2
10 1
10 0
Influence of the carbon black type and of the MFI of
the starting polymer on the resistivity:
Compounding: laboratory Brabender internal mixer.
Processing: compression moulding.
The higher the structure of the carbon black, the lower the percolation
threshold.
At equal structure, the carbon black of lower surface area gets an advantage
on resistivity that may be coming from the easier dispersion resulting
in smoother compounding.
The higher the meltflow index of the starting polymer, the lower the
percolation threshold.
171
24
13.50% E250 G
15% E250 G
10
strands pellets + pressed
plaques
6
4.6E+10
54
pellets +
injection moulding
Influence of carbon black loading and processing
on the resistivity:
Compounding: ZSK25 twin screw extruder.
Processing: injection moulding.
Injection moulding generates more shear than compression moulding.
The closest to the percolation, the more visible is that effect. A concentration
safety margin can overcome this phenomenon.

ENSACO ® Conductive Carbon Blacks in PC
Volume Resistivity (log Ohm.cm)
Izod (KJ/m 2 )
Tensile Strength (MPa)
12
11
10
9
8
7
6
5
4
3
2
Volume Resistivity (VR) in function of carbon black loading
1
5 10 15 20 25
12
11
10
9
8
7
6
5
Carbon Black concentration (%)
Izod impact strength, notched, in function of VR
E250 G
E350 G
E250 G
E350 G
4
1 2 3 4 5 6 7 8 9 10 11 12
Volume Resistivity (log Ohm.cm)
68
67
66
65
64
63
62
61
Tensile strength in function of VR
E250 G
E350 G
60
1 2 3 4 5 6 7 8 9 10 11 12
Volume Resistivity (log Ohm.cm)
Influence of the carbon black type
on the resistivity:
Compounding: ZSK57 twin screw extruder.
Processing: injection moulding.
Influence of the carbon black type on mechanical and
rheological performances:
Compounding: ZSK57 twin screw extruder.
Processing: injection moulding.
Although the concentration for percolation is double the level with
ENSACO ® 250 G, most mechanical properties are still better.
Tensile Strength for both carbon blacks is almost at the same level.
13

14
Rubber
Carbon black is one of the main ingredients
of any rubber compound. Conductive carbon
blacks are before all carbon blacks, to be mixed
and handled as any other reinforcing or semireinforcing
carbon black. They are high structure
materials bulky by nature. Although the
common carbon blacks are conductive by
nature and impart also conductivity to the
compounds when used in sufficiently high
loading, conductive carbon blacks have the
advantage to reach conductivities at lower loading
and are often used to give the final boost to
a compound already filled with other carbon
blacks. As carbon black structure is the parameter
determining the conductivity, structure
being an additive property, the combinations of
conductive and normal black can be predicted.
Specifications of rubber compounds being
usually quite complex and conductivity being
only one of the numerous physical requirements,
the use of carbon black blends is very
often the only solution.
In some specific cases, especially in special
polymers, it occurs that the conductive carbon
black is used by its own in order to maintain
mechanical properties and processing at a good
level.
ENSACO ® carbon blacks are, as mentioned
above, quite close to furnace blacks as far as the
reinforcing activity is concerned. Especially the
low surface area carbon blacks, grades 150, 250
and 260, are, due to their very easy dispersion,
quite performing in most rubber compounds.
ENSACO ® 350 is also used in some compounds
where small additions are required.
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Typical applications for ENSACO ® Conductive Carbon Black
A few conductive
applications:
belt cover compounds;
flooring;
conveyer belts;
hoses for fuel, for conveying
of powders, etc.;
cylinder coating;
shoe soles;
seals.
ENSACO ® 150 and 250 are also used in non
conducting applications where the compounder
can take profit of the low surface area and high
structure of those blacks:
low hysteresis with relatively high hardness;
good thermal aging;
very good tear strength;
very good dispersion, very good mechanical
performance at thin layer.
A few non-conductive
applications:
antivibration systems;
textile coating;
membranes;
articles exposed to chipping and chunking.
In the following pages there are some of the
results of experimental work carried out on
ENSACO ® Conductive Carbon Blacks in different
rubber compounds.
The data shown here are given as orientation
and are valid for the particular formulations
and sample preparation technique
mentioned. Results in other polymers, full
studies and publications are available upon
request.

NBR conductive hose compound
NBR NT 3945
Ensaco 250
N-472
N-550
ZnO
Stearic acid
DOP
Sulphur
Methyl Thuads
Amax
By courtesy of Bayer
Conductive CR conveyor belt cover compound
Bayprene 610 (CR)
Buna CB 10
MgO Powder
N-472
Ensaco 250
Vulkanox DDA
Vulkanox 4020
Ingralen 450
ZnO Powder
Rhenogran ETU-80
Stearic acid
By courtesy of Bayer
A B
Compound
ENSACO 250
A B
Compound
ENSACO 250
100
25
40
4
0.5
30
0.4
2
2
100
2
4
30
1.5
0.5
15
5
0.2
0.5
Compound
N-472
100
25
40
4
0.5
30
0.4
2
2
Compound
N-472
100
2
4
30
1.5
0.5
15
5
0.2
0.5
t90% (min)
Mooney ML (1+4) at 100° C
Vulcanizate data unaged at RT
Shore A Hardness
Stress-strain
Elongation at break (%)
Tensile Strength (Mpa)
Modulus 100% (Mpa)
Modulus 300% (Mpa)
Modulus 500% (Mpa)
Resistivity (Ohm.cm)
Tear Strength (N/mm)
Dispersion Rating DIK
t90% (min)
Mooney ML(1+4) at 100°C
Vulcanizate data unaged at RT
Shore A hardness
Stress-strain
Elongation at break (%)
Tensile Strength (Mpa)
Modulus 50% (Mpa)
Modulus 100% (Mpa)
Modulus 300% (Mpa)
Modulus 500% (Mpa)
Compression Set 24h at 70°C (%)
Resistivity (Ohm.cm)
A B
Compound
ENSACO 250
86.8
20.7
62
A B
Compound
ENSACO 250
11.46
45.7
70.9
339
13.8
3.9
8.6
12.6
79
32.4
62
676
23.4
1.2
2.4
9.2
16.1
18
100
Compound
N-472
11.37
47.2
72.2
311
14.8
4.6
10.3
14.4
360
31.8
Compound
N-472
85.8
21.8
64
64
540
22.4
1.4
2.7
11.5
20.6
19
800
15

16
FKM conductive compounds
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1 2 3 4 5 6 7 8 9
VITON A-32J - Fluoroelastomer 100 100 100 100 100 100 100 100 100
MgO
3 3 3 3 3 3 3 3 3
Ca(OH) 2
3 3 3 3 3 3 3 3 3
MT black
20 -
- -
-
-
- 20 20
ENSACO 250G
- 10 20 30 -
-
- 10 20
N-472 SCF
-
-
- - 10 20 30 -
-
VPA-2
1 1 1 1 1 1 1 1 1
Total phr 127.0 117.0 127.0 137.0 117.0 127.0 137.0 137.0 147.0
MT black % 15.7 0.0 0.0 0.0 0.0 0.0 0.0 14.6 13.6
E250G % 0.0 8.5 15.7 21.9 0.0 0.0 0.0 7.3 13.6
SCF N-472 % 0.0 0.0 0.0 0.0 8.5 15.7 21.9 0.0 0.0
Experimental data provided by DuPont Dow Elastomers, Japan
180
160
140
120
100
80
60
40
20
Mooney viscosity ML (1+10’), 100°C
(*)
0
1 2 3 4 5 6 7 8 9
(*)Rejected because uncurable.
Vulcanizate properties at 177°C for 10 min.
70
60
50
40
30
20
10
0
Compression set (%)
1 2 3 4 5 6 8 9
20
18
16
14
12
10
8
6
4
2
0
100
90
80
70
60
50
40
30
20
10
0
t 90% (min)
1 2 3 4 5 6 8 9
Shore A
1 2 3 4 5 6 8 9
14
12
10
8
6
4
2
0
Log Resistivity (Ohm.cm)
1 2 3 4 5 6 8 9

Typical applications for ENSACO® Conductive Carbon Black
Power cables
and accessories
NConductive carbon black is used in semicon
compounds for conductor and insulator shields.
NThe requirements for those compounds are
besides processing, a sufficient electrical conductivity,
a smooth or even supersmooth surface
finish, and high purity.
NFor strippable or easy strippable compounds
these requirements are added to a specific adhesion
strength between the insulating layer and
the insulator shield. These strippable or easy
strippable layers have to peeled of by hand or
using a specific peeling device.
NTypical polymer compositions are polyolefins
or copolymers; for strippable compounds quite
often blends of EVA and NBR are used.
Typical EVA/NBR strippable compounds
Levaprene 450
Perbunan NT 8625
Rhenogran P60
N-472
E 210
E 250
N-550
Antilux 654
Zn Stearate
Rhenovin DDA-70
Rhenofit TAC/CS
Percadox BC-408
Viscosity ML (4+1)
Rheometer@180 t90%
Mechanical properties
Non aged (diff. aged)
Tensile strength MPa
Elongation at break %
Modulus 100% MPa
Shore A
Peel strength hot air 100°C N
after 3 days N
after 21 days N
Volume resistivity (Ohm.cm)
Compound
N-472
90
10
3
40
40
10
1
1.4
4.3
5
56
3.6
16.5 (-19)
215 (-58)
11
87 (+7)
7
5
5
210
Compound
ENSACO 210
90
10
3
40
40
10
1
1.4
4.3
5
44
3.6
16.9 (-15)
180 (-50)
12.2
90 (+4)
3
4
3
6600
Typical EEA/EBA semicon compounds
EEA
EBA
E 250
Peroxide
Mixing cond. L/D15; Feed BC; Truput 30
Resistivity @ RT
Resistivity @ 90°C
Carbon black dispersion:

18
Self lubricating
polymers
NThe choice of a polymer-based self lubricating
solid for a particular application depends
mainly upon the operating conditions of:
temperature, chemical environment and the
maximum values of pressure (p) and sliding
speed (v). For each polymer or composite
material, a pv limit is quoted, which corresponds
to the pressure times the sliding speed
at which the material fails, either due to unacceptable
deformation, or to the high frictional
energy dissipated causes surface melting,
softening and excessive wear.
NThe pv limit of a polymeric material may
be increased by increasing its mechanical
strength (resistance to deformation), thermal
conductivity (reduction in surface temperatures)
and by decreasing friction (reduces frictional
heating). In practice, thermoplastics
(with the exception of PTFE) are mainly used
as pure solids, since their wear resistance and
frictional coefficient, are satisfactory for
most applications. Solid lubricant fillers or
fibre reinforcement (glass fibres, carbon
fibres, textiles) are only employed under the
more extreme conditions of load and speed.
NThe major polymers employed as self lubricating
solids/composites, are illustrated
below.
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Typical applications for TIMREX® Graphite and Coke
Thermoplastics Thermosetting polymers
polyamides*
polyester
polyacetal*
polyethylene (HDPE, UHMWPE)
Polycarbonate
poly (ether etherketone)*
polyphenilenesulphide*
polysulphone*
epoxy resins*
phenolic resins*
unsatured polyester*
polyimides*
Major polymers employed as self lubricating solids.
* polymers in which graphite
may be incorporated
N Graphite powder is widely used in polymer
composites, either alone or in combination
with reinforcing fibres, PTFE or various inorganic
fillers, e.g. mica, talc (bottom, right
table). Applications include gears, dry sliding
bearings, seals, automotive and micro-mechanical
parts. The properties of graphite which
favour its use in polymer composites are:
low friction lamellar solid
(reduces friction);
tendency to form a transfer film
on the countersurface
(assists in wear reduction, particularly
when graphite is applied as water based
dispersion i.e. LB 1300);
high thermal conductivity
(decreases temperature rise due to
frictional heating);
electrical conductivity
(prevent build-up of static charge which
may be a problem in some cases);
chemically inert
(used in conjunction with PTFE in
corrosive environments);
high thermal stability
(favours use in high temperature
applications, e.g. polyimide graphite
composites may be used up to 350°C).
Polymer Graphite content Other additives
polyacetal
polyamide 6
polyamide 11
polyamide 12
polyamide 6.6
polysulphone
polyphenilenesulphide
polyphenyleneoxide
PTFE
polymide
polymide
polymide
phenolic / epoxy resin
polyester thermoset
10%
5%
10%
30%
5%
15-30%
10%
10%
15-40%
15-40%
15%
40%
5-20%
5-20%
Examples of the use of graphite in self lubricating polymers.
-
-
glass fibre
PTFE
-
inorganic filler
glass fibre
inorganic filler
glass fibre
-
PTFE
CF
CF/glass fibre
CF/glass fibre
-
-
25%
15%
-
10%
30%
20%
10-20%
-
20%
10%

Incorporation of graphite powder into a
thermoplastic polymer will generally result in
a reduction in the friction coefficient (with
the exception of PTFE) but rarely improves
the wear resistance. This behaviour is illustrated
in the two graphs, which show the
mean friction coefficient and specific wear
rate for a stainless steel ball (ø = 5 mm) rubbing
on discs of graphite filled polystyrene
and polyamide at constant load (32.5 N) and
speed (0.03 m/s). The specific wear rates of
the graphite-polymer composites were calculated
from the diameters of the wear tracks
and the contact geometry.
In the case of polystyrene, addition of 30-
50% of a high purity macrocrystalline synthetic
graphite (T 75), reduced both friction
and wear rate. With polyamide however,
addition of a graphite similar to T 75 reduced
the friction coefficient, but caused a slight
increase in the wear rate, with the finer particle
size powder (KS 6) giving the better result.
In the case of low density polyethylene and
polypropylene, graphite incorporation causes
both an increase in friction and wear.
The results described above are thought to
be related to the strength of adhesion at the
polymer-graphite interface, which depends
upon the wettability of the powder by the
molten polymer, powder surface area to volume
ratio, surface chemistry, etc.
In simple terms, polystyrene shows a strong
affinity for the graphite surface, while polyolefins
show a weak affinity.
Interfacial adhesion increases with increasing
powder surface area to volume ratio, or
decreasing particle size.
Ball/Disc Friction & Wear Data
polystyrene/graphite filler
specific wear (m/Nm)x10 friction coefficient
12
0.4
10
8
6
4
2
0
3 -12
pure polystyrene 30% T 75 50% T 75
wear
friction
Influence of graphite addition on the specific wear rate
and friction of polystyrene
0.3
0.2
0.1
For this reason relatively fine graphite powders
(95%

20
Filled PTFE
Polytetrafluoroethylene (PTFE) exhibits a
very low coefficient of friction and retains useful
mechanical properties at temperatures from
-260 to +260 °C for continuous use.
The crystalline melting point is 327 °C, much
higher than that of most other semi- crystalline
polymers. Furthermore, PTFE is nearly inert
chemically and does not adsorb water, leading
to excellent dimensional stability. On the one
hand, these characteristics of PTFE are very
useful in the matrix polymer of polymer-based
composites which are used in sliding applications.
On the other hand, PTFE is subjected to
marked cold flow under stress (deformation
and creep) and reveals the highest wear among
the semicrystalline polymers.
NHowever, these disadvantages are very
much improved by incorporating suitable
fillers, allowing the use of PTFE in fields otherwise
precluded to this polymer.
NThe treated PTFE is generally known as
filled-PTFE. There are many kinds of filled-
PTFE composite because various fillers are
incorporated into PTFE and one or more
materials can be used simultaneously. Usually,
these fillers are in form of powders or fibers
intimately mixed with the PTFE.
NThe addition of fillers to the PTFE
improves or modifies its properties depending
upon the nature and quantity of filler:
remarkable increase in wear resistance;
decrease of deformation under load
and of creep;
reduction of thermal expansion;
some types of filler increase the
thermal and electric conductivity.
NFilled PTFE is often not as strong and
resilient as virgin PTFE. Sometimes, the filler
limits the resistance to chemical agents and
modify the electrical properties.
www.timcal.com
Typical applications for TIMREX® Graphite and Coke
TIMREX ® Graphite
and Coke fillers in filled-PTFE
TIMREX ® PC 40 Coke
TIMREX PC 40 Coke is calcined at high
temperatures offering low sulphur concentration,
low content of oversize particles, high
apparent density and high chemical stability
against most chemical substances. TIMREX ®
PC 40 Coke is added to the virgin PTFE in a
percentage by weight between 10 and 35%
along with small percentage of graphite.
Compounds made of PTFE and TIMREX ®
PC 40 Coke have excellent wear resistance
and deformation strength and compared to
the virgin PTFE, they have practically
unchanged chemical resistance and friction
behaviour.
Typical final materials that can be produced
with coke filled PTFE are:
engineering design components, slide bearings,
valve housing and valve seats for chemical
applications, piston sealing and guiding
elements for dry-running compressors.
TIMREX ®
KS44 Synthetic Graphite
NTIMREX ® KS 44 is a Primary Synthetic
Graphite obtained by the full graphitisation of
amorphous carbon materials through the well
known Acheson process. The process parameters
in the Acheson furnace such as temperatures
and residential times are all optimised in
order to achieve the perfect degree of crystallinity
and the lowest level of impurities
whereas others minor adjustments are made
during the material sizing and conditioning.
NThe percentage of TIMREX ® KS 44 used in
the filled PTFE vary between 5 and 15%.
NTIMREX ® KS 44 can be used alone or in
combination with glass or coke.
TIMREX ® KS 44 lowers the coefficient of
friction and is, therefore, often added to other
types of filled PTFE for improving this property
(and also to improve the lifetime of the
cutting tools during for instance the production
of gaskets and seals).
It improves the deformation under load,
strength and, to a minor degree the wear. Like
coke, it serves well in corrosive environments.
PTFE filled with TIMREX ® KS 44 are often
used in steering and shock-absorber gasket,
bearings as well as in slide films for anti-static
applications.

Influence of TIMREX ® Graphite
and Coke fillers in filled-PTFE
Wear resistance:
virgin PTFE shows much high wear as a result
of the destruction of the banded structure due
to easy slippage between the crystalline lamellae
in the bands.
The presence of well distributed carbon particles
in the filled PTFE partially avoid the slippage
between the crystalline lamellae in the
bands and therefore the wear resistance is
improved.
Deformation strength:
virgin PTFE deformation behaviour is somehow
similar to the mechanism previously
described. In someway the deformation phenomena
could be explained by the tendency
of slippage that occurs between the crystalline
lamellae. However, in this case the presence of
well distributed carbon particles in the filled
PTFE offers only a partial explanation to the
phenomena because also hardness of these
particles is important in determine an
improvement of the deformation behaviour.
Friction Coefficient:
the coefficient of friction for various filled
PTFE composites is weakly dependent upon
the incorporated filler, because a thin PTFE
film generally exists at the interface between
the body and counter-body. Consequently the
coefficient of friction is both similar in the
filled PTFE and virgin PTFE. This evidence is
true as long as no oversize particles are present
in the filler. In fact the presence of oversize
particles could lead to a radically modification
of the coefficient of friction. Because of that in
carbons as well as in other fillers is very important
the control of oversize particles.
21

22
Thermally
conductive polymers
NThe ability of a material to conduct heat is
known as its thermal conductivity. Thermal
conductivity itself is nothing else than transportation
of thermal energy from high to low
temperature regions. Thermal energy within
a crystalline solid is conducted by electrons
and/or discrete vibrational energy packets
(phonons*). Each effect, phonons and movement
of free electrons, contributes to the rate
at which thermal energy moves. Generally,
either free electrons or phonons predominate
in the system.
*Phonons
In the crystalline structures of a solid material,
atoms excited into higher vibrational frequency
impart vibrations into adjacent
atoms via atomic bonds. This coupling creates
waves which travel through the lattice
structure of a material. In solid materials
these lattice waves, or phonons, travel at the
velocity of sound. During thermal conduction
it is these waves which aid in the transport
of energy.
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Typical applications for TIMREX® Graphite and Coke
What is
thermal conductivity?
Scrap
PC 40 12
Typical data of thermal conductivity of graphite powders
pressed to density ≈ 2.2 g/cm 3 , 25°C
Thermal conductivity
of graphite
N The thermal conductivity in graphite is
generally dominated by phonons, and limited
by the crystallite size. In addition, due to
its particular structure, thermal conductivity
is different in the different directions of the
crystal. It is highly conducting along its layers
(ab direction) and not so well perpendicular
to the layers (c direction) because their is no
bonding between the layers. The thermal
conductivity of a perfect graphite crystal is
~3000 W/(m.K) in the ab direction and ~6
W/(m.K) in the c direction. NThe table
below shows the thermal conductivities of
TIMREX ® Graphite measured on pure
graphite compacts (obtained by Hipped
Samples; HIP 350 MPa, 1900°C). Thermally
conductive plastics can replace most metals
(i.e. aluminium and copper), ceramics, and
conventional plastics in heat-sensitive applications.
Thermal Conductivity W/(m.K)
20.00
15.00
10.00
5.00
Thermally
conductive polymers
Thermally conductive polymers are able to
evenly distribute heat generated internally
from a device and eliminate “hot spots.”
Possible applications for thermally conductive
plastics include heatsinks, heat exchangers,
appliance temperature sensors and many
other industrial applications. Also thermally
conductive elastomers can be found in a wide
variety of industrial applications such as gaskets,
vibration dampening, interface materials,
and heat sinks.
NVirgin polymers can be considered thermal
insulators having a thermal conductivity of
approximately 0.2 W/(m.K). By adding
TIMREX ® Graphite a final value up to 15-20
W/(m.K) can be achieved (as it is shown in
the following graph in which different types
of graphite powder were added to a PP
matrix) which represents an increase of 75 to
100 times compared to the unfilled polymer.
Thermal conductivity of graphite (in plane) - PP compounds
BNB 90
KS grades
10% KS+BNB90
0.00
0 20 40 60 80 100
Loading (% wt)

Typical applications for TIMREX® Graphite and Coke
Flame retardant
polymers
What is expandable graphite
and how does it work as flame retardant?
NExpandable graphite (EG) (or graphite salt) is
a halogen-free material consisting of graphite
and acid. The acid is intercalated between the
graphene layers. EG is manufactured by the
oxidation of natural graphite in a strong acid
such as sulphuric or nitric acid. After the reaction
the graphite is washed in order to remove
traces of acid left on the surface (typically the
final pH of our TIMREX ® Flare Grades range
from 4 to 8).
Expansion Volume (ml/g)
180.0
160.0
140.0
120.0
100.0
80.0
60.0
40.0
20.0
NWhen expandable graphite is exposed to heat,
it can expand to several hundred times its original
volume, and covers the entire burning surface
of the substrate with a “worm” like structure
of expanded graphite. NThe char, formed by
the expanded graphite, acts as an insulating
agent and dramatically reduces the heat release,
mass loss, smoke generation, and toxic gas emission
of the substrate.
TIMREX® Flare 100 Expansion behaviour vs Temperature
0.0
0 100 200 300 400 500 600 700
Temperature (°C)
Expansion behaviour
of TIMREX ® Flare Grades
The expansion volume of the graphite salt is
a function of the temperature. The temperature,
at which expansion begins, the so-called
onset temperature, mainly depends on
the type of acid (the graph shows the expansion
behaviour vs temperature of TIMREX ®
Flare 100). Particle size, carbon and acid
content also affect the expansion. The bigger
the particle size, the higher the expansion
volume. The higher the carbon content or
the acid contents the higher the expansion
volume.
Possible applications:
PU foams;
door & wall sealing;
intumescent pipe wraps;
rubber products;
textiles, carpets and mats;
coatings.
Advantages:
halogen free;
environmental friendly;
lower loading required compared to
other mineral flame retardant materials;
synergistic effect with other flame
retardant materials.
The information contained in this brochure
is believed to be correct. However, no warranty
is made, either expressed or implied
regarding the accuracy or the results to be
obtained from the use of such information.
The user assumes all risk and liability for
loss, damage or injury to property or others
resulting from the use of the material. No
statement is intended or should be construed
as recommendation to infringe any
existing patent.
23

Polymers 03.2008