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April 8, 2015
Overview
•
Thermax® Thermal Carbon Black
•
Thermax® vs. Furnace Black
•
The Thermax Advantage
•
•
•
•
•
•
•
•
•
•
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Natural Rubber
Nitrile Rubbers
Hydrogenated Nitrile
Polychloroprene
Fluoroelastomers
NBR/PVC Blends
Ethylene Propylene Rubbers
Chlorosulfonated Polyethylene Rubbers – CSM
Butyl and Halobutyl Rubbers
Questions & Answers
Cancarb
April 8, 2015
Thermax®
• Carbon black can be broadly defined as very fine particle
aggregates of carbon, possessing an amorphous quasigraphitic molecular structure
• The most significant areas of distinction between thermal
black and furnace black are particle size and structure
• Thermax®, thermal carbon black, due to its higher particle
size (280 nm) and lower structure, compared to even the
most coarse furnace black, can be translated into excellent
rubber compound properties
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Thermax® vs. Furnace Black Grades
Particle Size Diameter
N762
(80nm)
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April 8, 2015
N990
(280nm)
Thermax® vs. Furnace Black Grades
Low Structure
Moderate Structure
High Structure
N990
N762
N550
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April 8, 2015
The Carbon Black Spectrum
OAN (DBP) ABSORPTION (ml/100g)
INCREASING STRUCTURE
140
N343
N650
120
N550
N121
N339
N220
N539
N110
N330
100
N660
80
N774
N762
60
40
N326
N990
20
0
0
10
20
30
40
50
60
70
80
90 100 110 120
NITROGEN SURFACE AREA (m2/g)
DECREASING PARTICLE SIZE
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April 8, 2015
130
140 150
160
Influence of Carbon Black on
Properties
Rubber Property
Mixing temp.
Dispersion
Viscosity
Green Strength
Extrusion Quality
Scorch Safety
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April 8, 2015
As Particle size
Increases
As Structure
Decreases
Influence of Carbon Black on
Properties
Rubber Property
Tensile
Elongation
Hardness
Tear resistance
Compression set
Heat build up
Abrasion resistance
Resilience
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April 8, 2015
As Particle size
Increases
As Structure
Decreases
The Thermax® Advantage
The properties of Thermax® can be translated into rubber
compounds with:
• Lower heat build-up, especially during extrusion, which is very
important for halogen bearing rubbers and high hardness
compounds
• Low hysteresis loss in dynamic applications, for example;
automotive engine mounts
• Reduced volume swell in aggressive fluids
• Reduced cost
• Low compound viscosity which is essential for injection molded
and sponge compounds
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April 8, 2015
Natural Rubber (NR)
Natural Rubber Structure
CH3
• Natural rubber is polyisoprene
– CH2 – C = CH – CH2 –
• There are four possible isomers of
natural rubber
cis–1,4 Isomer
-CH2
CH2C=C
CH3
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April 8, 2015
• 1,4 structure means that ‘C’ atoms 1
and 4 are joined in forming the chain
• In the cis-1,4 structure both carbon
atoms 1,4 forming the chain are on
the same side of the double bond
Natural Rubber (NR)
• Natural Rubber has outstanding mechanical properties and
fatigue resistance making it a very popular choice in
dynamic applications
• Natural rubber consists of polymer chains all having almost
100% perfect cis–1,4 structure. The true chemical name
for this polymer is in fact, cis-1,4-polyisoprene
• When the units in a macromolecule all consist of the same
molecule, the polymer is said to be stereo regular
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April 8, 2015
Properties of Natural Rubber (NR)
Natural Rubber:
• Crystallizes on stretching, resulting in:
• high gum tensile strength
• high tensile strength/elongation @ break
• very high tear strength & hot tear resistance
• excellent De Mattia cut growth resistance
• Gives a glass transition temp (Tg) of approximately -75°C
• Has high resilience
• Has excellent tack & green strength properties
• Imparts low damping (hysteresis) and low heat build-up in
dynamic deformation
• Is unsaturated (double bonds), resulting in poor resistance
to:
• Heat aging
• Ozone
• Oils and hydrocarbons
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April 8, 2015
Applications of Natural Rubber
Common Applications of Natural Rubber are:
• Truck tire tread (Tear, hot tear, low heat build-up)
• Passenger radial (Flexibility, low heat build-up)
• Anti-vibration (Dynamic deformation)
• Conveyor belting (High mechanical properties, tear)
• Adhesive tapes and solutions (Tack)
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April 8, 2015
The Thermax® Advantage in Natural
Rubber Compounds
• Thermax® maintains the inherent good
properties of the natural rubber polymer
dynamic
• The best choice for anti-vibration applications
• Thermax® lowers compound hardness while retaining the
good tack properties inherent to natural rubber
• Excellent for cushion gum compounds
• In wiper blade applications, higher loadings of Thermax®
lower the rubber content of the compound which is
essential for low noise and a good surface finish.
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NR Compound Example Using
Thermax®
Natural Rubber Engine Mount
SMR
Zinc Oxide
Stearic acid
A.O. TMQ
N 762
Thermax N990
Aromatic Oil
CBS
TMTD
Sulfur
100
3
1
1.5
15
45
15
3
0.5
0.5
100
3
1
1.5
15
70
15
3
0.5
0.5
Cure time @ 160°C
Hardness
Tensile strength
Elongation @ Break %
11‘
43
206
535
11‘
49
178
480
Dynamic testing at 20 Hz
Tan Delta at 25°C
0.084
0.027
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April 8, 2015
Nitrile Rubber (NBR)
Nitrile Structure
butadiene
- CH2 - CH = CH - CH2
-
+
acrylonitrile
- CH2 - CH CN
Polymer Unit
- (CH2 - CH = CH - CH2)n -
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CH2 - CH
(
)
CN
-
m
Nitrile Rubber (NBR)
• Nitrile rubbers are high molecular weight copolymers of
1,3-butadiene and acrylonitrile
• The percentage of acrylonitrile content can be varied
from 18% to 50%, and will influence the performance
characteristics of the polymer
• The great variation in acrylonitrile content possible with
nitrile rubber, allows for compounds to be customized to
highlight specific required properties
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April 8, 2015
Nitrile Rubber – Effect of Acrylonitrile
Content
Increases
Density
Processability
Cure rate – Sulphur Cure System
Oil/fuel resistance
Compatibility with polar polymers
Thermoplasticity
Stiffness
Tensile
As ACN Increases
Abrasion resistance
Heat – aging resistance
Decreases
Resilience
Cure rate – peroxide system
Low temperature flexibility
Air/gas permeability
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April 8, 2015
Nitrile Rubber – Effect of Mooney
Increases
Acceptance of fillers/plasticizers
Incorporation time of fillers
Mixing temp
Sheet formation time on mill
Mill shrinkage
Green strength
Modulus
As Mooney Increases
Decreases
Porosity
Compression set
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April 8, 2015
Properties of Nitrile Rubbers
Nitrile Rubber:
• Has very good oil and fuel resistance
• Can perform over a wide temperature range
• Has inherently good resistance to gas permeation which
increases as the level of acrylonitrile increases
• Can be blended, up to 50%, with polyvinyl chloride (PVC) to
produce
compounds
that
exhibit
good
weathering
characteristics in addition to good dynamic properties
• Can be co-polymerized with methacrylic or acrylic acid to
produce carboxylated nitrile (XNBR), which is noted for its
excellent dynamic properties and abrasion resistance
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April 8, 2015
Applications of Nitrile (NBR)
Common Applications of Nitrile Rubber are:
• Gaskets and seals – NBR, XNBR (for high hardness)
• Hoses – NBR (mainly in tubes), NBR/PVC (mainly in covers)
• Belting – NBR
• Rollers – NBR, XNBR (for high hardness)
• Cable Jackets – NBR/PVC
• Textile (spinning cots/aprons) – NBR, NBR/PVC, XNBR
• Industrial footwear – NBR, NBR/XNBR blend, NBR/PVC sponge
• Insulation – NBR/PVC sponge
• Molded/extruded components for various industries & automotive
• Fabric proofing – NBR
• Milking inflation - NBR
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The Thermax® Advantage in NBR
Compound Applications
• Higher loadings are achievable with Thermax®, which
reduces the rubber content enabling for lower swell in
aggressive fluids
• Gaskets and seals
• Thermax® promotes good extrusion properties and low
heat development, avoiding potential scorch problems.
This is critical for high hardness compounds
• Hydraulic hose tubing
• Thermax® maintains the desired hardness of a compound
while lowering the viscosity for effective blowing
• NBR/PVC Sponge Insulation, hoses and soles
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April 8, 2015
Nitrile Compound Example Using
Thermax®
Hydraulic Hose (Broad Temperature Range)
Nitrile Rubber
ZnO
St. acid
Processing Additive
A.O. Aminox
A.O. ZMBI
N550
N990
ageing
Paraplex G-25
KP 140
Sulfasan R
CBS
TMTD
Cure @ 166°
SH / TS / EB
Vol. swell %
100 (33-34% ACN, 75-80 Mooney)
5
1
2
2
(DPA + Acetone reaction product)
2
(Zn Salt of 2 – Mercaptobenzimidazole)
50
Suitable blend for good processing,
50
vulcanizate properties and good heat
>
Blend of polyester and phosphate
10 >
plasticizers for resistance to heat extraction
10
and low temperature cracking
1
3
3
15'
70 / 152 / 270
19 (ASTM Oil 3 / 70h 135°C)
Blending with Thermax N990 helps improve scorch safety during extrusion due
to lower heat development. Higher filler loading improves over all extrusion
properties and sealing with end couplings
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April 8, 2015
Hydrogenated NBR (HNBR)
Hydrogenated nitrile rubber is based on NBR that has been
chemically altered (hydrogenated), resulting in a much lower
amount of unsaturation in the polymer backbone.
HNBR
exhibits significantly improved heat resistance, compared to
NBR, while retaining excellent oil and fuel resistance.
HNBR Range
% Hydrogenation
% ACN content
~ 85 to 99+
17 to 50
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April 8, 2015
Mooney (ML 1+4 @ 100°C)
50 to 150
Comparison with NBR for 50 phr FEF
compound-Peroxide cured
HNBR+ 50 phr FEF
99+ % hydrogenation
38% ACN
55* Mooney
NBR+ 50 phr FEF
38% ACN
50** Mooney
Mooney (ML 1+4 @ 100°C)
43
86
Hardness (Shore A)
68
76
T.S. (M.Pa)
17.5
21.9
EB (%)
390
180
Tear Die C (KN/m)
Comp. Set % (168h/150°C)
15
18
16.7
27
Abrasion (DIN mm3 loss)
Air Ageing (168h/150°C)
145
260
Hardness
+8
+17
T.S. (%)
Nil
Brittle
EB (%)
-30
Brittle
The significant improvements in the properties of HNBR over NBR, especially in
compression set & heat ageing, bring HNBR very close to specialty rubbers.
*ML 1+4@125oC
**ML 1+4@100oC
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April 8, 2015
Hydrogenated NBR (HNBR)
HNBR*
ACM
FKM
VMQ
Tensile
1
3
3
7
Heat Resistance
3
3
1
1
Comp. Set
2
2
1
1
Low Temp
3
5
7
1
Gear Oil
1
1
4
7
ASTM Oil #1
1
3
4
7
Sour Gasoline
2
5
1
7
Rating:1 Best; 7 Worst
*99+ % Hydrogenation
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April 8, 2015
Applications of HNBR
• Timing belts (automotive) – ozone resistance, flexing
• Power steering rotary shaft seals
• ‘O’ rings
• Oil well specialties
• Rollers
• Air conditioning hoses for cars
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April 8, 2015
The Thermax® Advantage in HNBR
Compounds Applications
• HNBR rubbers have inherently good mechanical properties and
do not require a reinforcing black. Thermax® maintains the good
mechanical properties of HNBR while lowering the compound
viscosity which is essential for easy processing
• Thermax® does not degrade the excellent compression set of the
HNBR polymer
• Higher loadings are possible with Thermax® resulting in lower
polymer content which provides lower oil swell and a significant
reduction in the overall compound cost
• Thermax® allows for extrusion with lower heat build-up giving
better scorch safety and further improved impermeability of
HNBR
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April 8, 2015
HNBRLow
Compound
Example
Compression
SetUsing
HNBR Seal
Thermax®
Low Compression Set Seal
TORNAC A 38.55 (99.5% saturation)
Thermax® N990
Plasticizer WB 300*
ZnO
Stearic acid
Trigonox 101-45**
TAIC
ML 1+4 @ 100°C
MS Mooney Scorch at 125°C
Cure time at 180°C
SH/TS/EB
Air aging 150°C / 168H
Compression Set 70 h / 150°C
100
50
5
5
1
8
3
70
>25 ‘
9’
60/146/235
+8/-3/-40%
12
Thermax® maintains good low compression viscosity/mold flow, allows for
less polymer content, low swell, adequate tensile strength and excellent
compression set
*Mixture of Aliphatic / Aromatic polyesters
** 2,5 dimethyl – 2,5 bis (tert butyl peroxy) hexane (Akzo).
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NBR/PVC Blends
• Both NBR and PVC are polar which makes them very
compatible, typically a 70/30 ratio
• NBR provides resistance to heat and organic fluids but has
poor resistance to weathering and ozone due to
unsaturation.
• PVC provides resistance to weathering, ozone and aliphatic
hydrocarbons oils
• PVC also improves processing, reduced flammability and
mechanical properties such as T.S., tears and abrasions
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April 8, 2015
Carboxylated NBR (XNBR)
• Carboxylated NBR (XNBR) is a terpolymer NBR with acidic
organic monomer (typically 1 & 7%) carboxylic acid as a
third monomer
• Reactions of ZnO and Carboxylic Acid result in a matrix with
significantly increased mechanical properties, such as higher
hardness, abrasion resistance and tear strength
• Although sacrifice in processing (mill and mould sticking)
scorch, resilience and low temperature resistance, product
retains the basic properties of NBR (oil & fuel resistance)
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April 8, 2015
Applications
• Gasket and Seals - mainly NBR, high hardness seals ex/
Mud Pump – XNBR
• Hoses – NBR mainly in tubes, NBR/PVC bend mainly in
cover
• Beltings
• Rollers – NBR, XNBR for higher hardness rollers
• Cable Jackets – NBR/PVC blends
• Textile – spinning cots/aprons, NBR, NBR/PVC, XNBR
• Industrial Footwear – NBR, NBR/XNBR blend, NBR/PVC
sponge soiling
• Insulation – NBR/PVC sponge
• Moulded/extruded components for various industries,
automotive
• Fabric proofing – protective coatings, NBR
• Milking inflation – NBR, resistance to fat
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April 8, 2015
NBR/PVC Blend Example Using
Thermax®
Compound 1
Compound 2
Gasohol Resistant Hoses
NBR/PVC Blend70/30
100
100
Sulphur
1.5
1.5
ZnO
5
5
St. acid
1.5
1.5
N550
25
30
Thermax® N990
45
60
DOP
23
30
A.O. ODPA
1.5
1.5
P. Wax
3
3
TMTM
.5
.5
ML, 1+4@ 100°C
34
34
MS, t5 @125°C
23’
22’
Cure Time @ 160°C
7.5’
7.5’
SH/TS/EB
68/143/450
70/131/415
Comp. set 22 h/70°C
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27
Ageing in M15 test fuel (FAM 85 – Methanol 15), 48h at 23°C
Change
-18/-59/-60/+47.8v
-19/-27/-51/+39v
High loading of Thermax® lowers the polymer content allowing for low
swell in aggressive fuels, low compression set and good extrusion.
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April 8, 2015
Polychloroprene (CR)
Polychloroprene Structure
2-chlorobutadiene
CH2 = C – CH = CH2
trans-1,4 polychloroprene (88-92 %)
-CH2
C=C
Cl
Cl
Chloroprene (liquid)
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CH2-
Similar to trans-1,4 isoprene but, the
‘CH3’ group has been replaced by ‘Cl’
Polychloroprene (CR)
• Polychloroprene is often called neoprene. Neoprene is, in
fact, the trade name of Dupont Dow Elastomers
polychloroprene product line
• Polychloroprene has a structure similar to that of natural
rubber except one of the methyl side groups is replaced by
a chlorine atom and it is a trans-oriented molecule
• Polychloroprene can be sulfur modified or mercaptan
modified to provide specific desired properties
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April 8, 2015
Properties of Polychloroprene (CR)
Polychloroprene Rubber:
Crystallizes on stretching, allowing for:
• High gum tensile strength; similar to Natural Rubber (NR)
• Very good fatigue resistance
• When sulfur modified, will provide:
• Excellent fatigue resistance
• Highly resilient compounds
• High tear resistance
• When mercaptan modified, will provide:
• Better raw polymer stability
• Good resistance to heat
• Good resistance to compression set
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April 8, 2015
Applications of Polychloroprene
Common applications of polychloroprene rubber are:
• Adhesives – polarity-bonding
• V-belts – tack and fire resistance
• Timing belts – tack and fire resistance
• Bellows – high flexibility
• Automotive seals
• Bridge bearing pads – good dynamic properties and ozone
resistance
• Wire and cable – resistance to abrasion, oil, flame and weathering
resistance
• Hose (especially covers) – good weathering resistance
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April 8, 2015
The Thermax® Advantage in
Polychloroprene Rubber Compounds
• Thermax® will not degrade the inherently
mechanical properties of polychloroprene
good
• Thermax® lowers the compound viscosity which is
essential for lower heat build-up during extrusion and
good mold flow
• Thermax® will maintain the good compression set of the
polychloroprene rubber
• Higher loading of Thermax® is possible resulting in a
lower rubber content which decreases oil swell and
reduces the compound cost
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April 8, 2015
Polychloroprene Compound Example
Using Thermax®
Wiper Blade Compound
Neoprene WRT
SMR CV 60
ZnO
MgO
Stearic acid
Thermax® N990
SRF
Paraffinic Oil
DPG
TMTD
Sulfur
6 PPD
TMQ
MC Wax
Hardness
60
40
5
4
2
40
20
2-3
0.5
0.5
1.0
1.5
1.5
2
60
High loading of Thermax® reduces the polymer content (cost savings) which
helps for low noise and gives a “clean” product & surface finish
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April 8, 2015
Fluoroelastomers (FKM)
Fluoroelastomer Structure
- (CF2-CH2)X
-
(CF-CF2)Y
-
(CF2-CF2)Z
CF3
VF2
Vinylidine
Fluoride
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HFP
Hexafluoropropylene
April 8, 2015
TFE
Tetrafluoroethylene
Fluoroelastomers - FKM
• Fluorocarbon elastomers are a very popular choice for
difficult sealing applications
• Fluoroelastomers are created by substituting fluorine for
hydrogen on a carbon-based macromolecule
• Unlike hydrocarbon rubbers, which are non-polar,
presence of fluorine creates polar molecules
the
• Fluoroelastomers are expensive and difficult to process due
to their relatively high molecular weight
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April 8, 2015
Properties of Fluoroelastomers
Fluoroelastomers:
• Can be compounded to provide high heat resistance and thermal
stability
• Have excellent oil & gasoline resistance
• Have excellent hydrocarbon-based solvent resistance
• Have very good impermeability
• Are flame resistant
• Are resistant to weathering
• Have excellent compression set resistance
• Are expensive
• Tend to have high Mooney viscosities which accelerate heat buildup when mixing
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April 8, 2015
Applications of Fluoroelastomers
Common applications of Fluoroelastomers are:
• Automotive – Valve Stem Seals, Shaft Seals, ‘O’ Rings
• Aerospace – ‘O’ Rings for Hydraulic, Lubricating and Fuel Systems
• Oil Field – Packers & Blow-out Preventers
• Industrial – Expansion Joints in Mines, Gaskets, Valve & Pump
Linings
• Hoses – Fuel Lines, Turbo Chargers, Bio-diesel
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April 8, 2015
The Thermax® Advantage in FKM
Compound Applications
• High loadings of Thermax® will not reduce the excellent
compression set and low swell inherent to FKM
• Excellent for ‘O’ ring and seal applications
• The higher loading ability of
impermeability of the compound
Thermax®
improves
the
• The best choice for fuel line hose veneer
• The specific gravity of Thermax® is similar to that of FKM, so
higher loading of Thermax allows for the same volume of
compound to be produced while using less of the expensive
FKM elastomer, without sacrificing the desired compound
properties.
• Overall compound cost reduction
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April 8, 2015
FKM Compound Example Using
Thermax®
FKM O-ring
Compound 1
Dyneon FC 2176
Maglite D
100
3
100
3
Calcium Hydroxide
SRF
6
20
6
-
Compound 2
Thermax® N990
Press cure 10‘@177°C+Post cure 24hrs@260°C
30
Tensile Strength (psi)
Elongation at Break (%)
2120
220
1970
290
Shore A Hardness
Air Ageing 70 hrs/276°C
80
76
Tensile Strength (psi)
Elongation at Break (%)
1695
330
1405
295
Shore A Hardness
Compression set (%)
81
50
77
28
- Method B (0.139” O rings) 70 hrs/200°C
Thermax® enables higher loading while maintaining adequate original
mechanical properties with excellent ageing properties, compression set
resistance and low swell
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April 8, 2015
Ethylene Propylene Diene Rubber
(EPDM)
Structure
CH2 = CH2
Ethylene
CH3
|
+ CH = CH2 + A Diene Monomer
Propylene
Diene Monomers Used in EPDM
• DCPD - dicyclopentadiene
• ENB
- ethylidene nobornene
• VNB - vinyl norbornene
Typically, ethylene comprises 45% to 80% of the polymer with the
diene making up 2.5% to 12%.
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April 8, 2015
Ethylene Propylene Diene Rubber
(EPDM)
Increasing the ethylene content in EPDM provides:
• Improved cold green strength
• Excellent theroplasticity which improves extrusion and mold
flow characteristics
• Increased filler and oil loading ability
• Higher heat resistance
• Good cured tensile strength properties
But:
• It is responsible for less building tack
• It is more difficult to mix
• Mill processing at low temperatures is difficult
• Compression set and recovery in cold temperatures is poor
• Flex resistance and elastic recovery are reduced
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April 8, 2015
EPDM – Molecular Weight
Distribution
EPDM Polymer can be produced with a range of Molecular Weight
Distribution (MWD).
High molecular weight distribution EPDM provides for:
• Excellent hot green strength, important for shaping and
continuous vulcanization
• High collapse resistance critical for hollow extruded sections
• Less porosity in extrudates
• Excellent physical properties
• Low compression set
• Improved resilience
• Facilitates oil and filler extension which improves the
difficult processing characteristics common to high MWD
polymers
• Higher loading of filler for lower cost compounds
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April 8, 2015
Ethylene Propylene Diene Rubber
(EPDM)
Increasing the diene content of the polymer provides:
•
•
•
•
•
49
Shorter cure times
Higher resilience
Higher modulus
Lower compression set
Cure compatibility with unsaturated rubbers
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April 8, 2015
Properties of EPDM
EPDM based rubber offers:
• Excellent weather and ozone resistance
• Excellent high & low temperature resistance
• Excellent water and chemical resistance
• Excellent dielectric properties
But,
• Poor resistance to oils and hydrocarbon solvents
• Poor adhesion
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April 8, 2015
Applications of EPDM Rubber
Automotive industry
Extruded Profiles – solid and sponge
• Hoses – Radiator and Heater
• Seals and grommets
•
Appliance Industry
•
Washing machine parts – gaskets, elbows and hoses
Construction Industry
Glass profiles
• Flooring
• Membranes
• Roofing
•
Electrical Industry
•
Low and Medium voltage cabling – cable jackets
Chemical Industry
Hoses
• Seals
•
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April 8, 2015
EPDM Compound Example Using
Thermax®
Automotive Moulded Sponge
Keltan 512
ZnO
St. Acid
Benzoic acid
Thermaxx® N990
Winnofil S (Coated pptd CaCO3)
Sunpar 150
Vaselin
TMTD
MBTS
Sulphur
Benzene Sulphohydrazide
Benzene 1,3 Disulphohydrazide
100
5
1
1
100
35
60
10 Rotor/Roll Release
2
2
2
3
3
ML 1+4@100°C
Cure time 15’@160
Specific Gravity
19
0.52
Higher Loading reduces costs. Low compound Mooney helps efficient
blowing, gives uniform cell structure
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April 8, 2015
Metallocene EPDM Technology
• The introduction of EPDM in the world market produced by
Metallocene Catalyst Technology has increased the scope for
the usage of Thermal Black in these rubbers considerably
• EPDM produced by Metallocene Catalyst Technology has very
high molecular weight compared to traditional EPDM Rubbers
produced from solution and suspension polymerization
technology
• EPMD Rubbers with Metallocene Technology are very difficult
to process when compounded with furnace blacks alone.
Blending Thermax in blend with the furnace black lowers the
compound viscosity allowing for easy processing without a
negative affect on mechanical properties
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April 8, 2015
The Thermax® Advantage in EPDM
Compound Applications
• High loadings of Thermax® can reduce the compound cost
without sacrificing compression set and dynamic properties
• Thermax reduces the compound viscosity which improves
processing, blowing and molding properties
• The very low grit level of Thermax maintains excellent
surface finish and ensures a uniform cell structure in sponge
applications.
• The excellent dispersion of Thermax results in consistent heat
transfer throughout the extrusion and uniform cooling
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Chlorosulfonated Polyethylene
Rubbers (CSM)
Structure
- (CH2-CH2)x – (CH2-CH)y – (CH2-CH)z |
|
Cl
SO2
|
Cl
Polyethylene, a low cost plastic, is chemically modified to a
cross-linkable rubber, retaining some of the important
properties of polyethylene such as chemical resistance and
electrical properties
This polymer is almost exclusively produced by DuPont
Performance Elastomers under the trade name Hypalon®. On
May 7th, 2009, DuPont announced that it will cease production
of Hypalon® and completely exit the CSM business
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Properties and Grades of CSM
Properties
• Excellent resistance to weather, ozone, sunlight, oxidation,
alkalies and acids
• Good resistance to oil and gasoline
• Good flame resistance, abrasion resistance
• It is close to polychloroprene in most properties but superior
in resistance to acids, alkalies, solvents, Ozone and oxidation
with better color stability
Grades
• Depending on the Cl content, range 24% to 43%, ‘S’ content
around 1%, varying Mooney
• Increasing Cl content give oil and flame resistance
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Applications of CSM Rubbers
Grade
Cl content (%)
Hypalon 40/40S
35
Hoses
W&C
Rolls
Hypalon 45
24
W&C
Low Temp. Applications
Hypalon 48/48S
43
Excellent oil resistance
low permeability to Freon
Air Conditioner Hoses
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Mooney Viscosity
ML 1=4 @ 100°C
56/45
37
78/62
Butyl Rubber (IIR)
Structure
CH3
|
- CH2 – C |
CH3
Isobutylene
+
CH3
|
- CH2 – C = CH - CH2 -
Isoprene
Butyl Rubber is a copolymer of isobutylene and a small amount of
Isoprene, typically around 2%
Chlorobutyl (CIIR) and bromobutyl (BIIR) rubbers are produced
in a similar manner, but with and additional halogenation stage
required
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Properties of Butyl Rubbers
•
Presence of “bulky” isobutylene groups causes slow movement of the
polymer chain which gives butyl rubber excellent impermeability to air,
oxygen and water
• -CH3 groups along the chains interfere with each other, reduce the speed
with which the molecules
•
Low unsaturation makes Butyl more resistant to heat ageing and to attacks
by acids, alkalis, oxidizing agents, ozone, water and steam, than general
purpose polymers such as SBR, BR and NR
•
Butyl rubber is very similar in structure to polyisobutylene and has a similar
glass transition temperature (Tg) of -70°C
•
Butyl has low resilience and very poor resistance to compression set, oil and
hydrocarbon based solvents
•
Low unsaturation slows the compound cure rate and reduces Butyl’s
compatibility with the more unsaturated rubbers such as NR, SBR and BR.
Even small amount mixed in with these rubbers gives a disastrous effect on
compound properties
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Halobutyl Rubber
Isoprene
Halobutyl
CH3
|
Add X2
-CH2-C=CH-CH2X=Cl or Br
CH3
CH2
+
|
||
- Minus H
(-CH2-C-CH-CH2-) + (X )
(-CH2-C-CH-CH2-) + (HX)
+
|
|
X
X
• Virtually all halogenation takes place at the isoprene portions of the IIR
Chains which represent approximately 2.0 mole% of the IIR Co-Polymer
• Commercial chlorobutyls contain 1.1 to 1.3% weight of chlorine and
bromobutyls contain 1.9 to 2.1% weight of Bromine
• Stearic hindrance of the double bond favors substitution rather than
addition, so most of the unsaturation is retained, although it is now
largely isomerised
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Butyl versus Halobutyl Rubber
Butyl rubber
Chlorobutyl
Bromobutyl
Cure reactivity
Compatibility with other unsaturated rubbers
Tack
Cure adhesion with other rubbers
• Increased cure compatibility reduces the need for stringent
precautions against contamination with other unsaturated
rubbers
• Flexibility and resistance to dry heat are almost identical for
both Chloro and Bromobutyl rubber
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Permeability of Halobutyl
Typical Tire Inner Liner Compound
Permeablility rates at 65°C
100% NR
100% SBR
HIIR/NR (60:40)
100% HIIR
Air
8.3
6.8
3.1
1.0
Moisture
13.3
11.0
3.0
1.0
The excellent permeability of Halobutyl rubber makes it a very
popular choice for tire inner liners
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Applications of Butyl and Halobutyl
Rubber
• Inner tubes for tires (IIR, HIIR)
• Heat resistant conveyor belts (HIIR)
• Tire Inner liners (HIIR)
• Tank linings (HIIR)
• Side Walls (HIIR)
• Dampers/bridge bearing pads (IIR/HIIR)
• Tire curing bladders (HIIR)
• Adhesives/sealants (cross-linked IIR, HIIR)
• Steam/Automotive Hoses (HIIR)
• Pharmaceutical closures (HIIR)
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The Thermax® Advantage in IIR &
HIIR Compound Applications
• High loadings of Thermax® can reduce the overall compound
cost without a significant loss in compound properties
• The higher loading ability of Thermax® improves the
impermeability of the compound by replacing polymer with
impermeable filler
• Thermax can raise the viscosity of the compound making it
easier and less expensive to process
• Improved adhesion can be achieved with Thermax® which is
very important for inner liner and other rubber to rubber
bonding applications.
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Questions & Answers
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