Processing Aids
Fluoroelastomers

Technical Information
Introduction

Handling Precautions

VPA No. 1 is a general-purpose processing aid useful inall types of molded goods made from Viton™. It provides
smooth preforms, slightly faster cure rates, and excellent
mill and mold release characteristics. It has little or noeffect on vulcanizate properties.

VPA No. 1 and VPA No. 3 can cause eye and skinirritation. Avoid contact with eyes, skin, and clothing andavoid breathing dust. Use with adequate ventilation andwash thoroughly after handling. In case of eye contact,
immediately flush eyes with plenty of water for at least
15 min and call a physician.

VPA No. 2 is a particularly effective extrusion aid allowing
compounds of Viton™ to extrude faster, cooler, andsmoother. It has some adverse effect on high temperaturecompression set.

VPA No. 2 has no known toxicological hazards. Keep allcontainers closed to avoid contamination. Store in a cool,dry place.

VPA No. 3 provides the best mold release. lt has little
or no effect on standard physical properties, including
compression set resistance, and increases the cure rateof bisphenol-cured systems. VPA No. 3 is best suited formolding operations with automatic part removal and tightcompression set resistance requirements.

Before compounding or processing Viton™ fluoro­
elastomers, read Chemours technical bulletin “Handling
Precautions for Viton™ and Related Chemicals.”

Applications
The VPA processing aids are recommended for use
in Viton™ for the following applications: O-rings, seals,
molded shapes, diaphragms, and tubing. The comparativeadvantages of this family of processing aids in different
operations are shown in Table 1.

Product Descriptions
VPA No. 1

VPA No. 2

VPA No. 3

Physical Form

PowderFlakePellet

Color

Light tan towhiteYellow

Tan to lightbrown

Composition

Wax/
aromatic sulfur
compoundVegetablewax

75% sulfur
compound oninert carrier

Specific Gravity

1.26

0.99

1.43

Melting Point,°C (°F)150 (302)

80 (176)—

Recommended
Level, phr

0.5–2

0.5–2

0.5–1.5

Viton™

Fluoroelastomers

Table 1. Comparison of Process Aids in Viton™
Mold Release

Mill Calender Release

Extrusion Smoothness

Compression Set Resistanceo/++o/+o/–VPA No. 2+++++–VPA No. 3++

oooVPA No. 1++ Very positive effect+ Positive effecto No effect– Negative effectProduct Descriptions

ingredients and added to the batch. As with all wax-type
processing aids, proper extruder temperatures are very
important. A cool screw and barrel in the feed sectionof the extruder are particularly important to prevent
stock slippage on the screw (see Table 3 for suggestedconditions). Extrudates containing VPA No. 2 are
generally smooth and glossy.

VPA No. 1
VPA No. 1 is recommended for all types of molded goods
made from Viton™. It is an effective mill release agent
and is particularly useful on mills with inadequate coolingfacilities. It can be premixed with other compounding
ingredients and added to the batch. It has little or noeffect on processing safety, but has a slight activating
effect on cure rates at 177 °C (351 °F). Rod-type
preforms from compounds containing VPA No. 1 aresmooth and uniform.

VPA No. 2 has little or no effect on processing safety,
cure rate, or stress/strain properties. It does have anadverse effect on high-temperature compression set.
Also, 2 phr of VPA No. 2 in a standard formulation withViton™ E-60C will increase shrinkage approximately 0.4%
after an oven post-cure of 24 hr at 232 °C (450 °F).

Note: Complicated extrusion profiles from compounds
containing VPA No. 1 are not quite as smooth as thoseobtained with VPA No. 2.

VPA No. 3
VPA No. 3 is recommended for all types of molded goodsof Viton™. It can be premixed with other compounding
ingredients and added as usual. It increases cure rateand can affect scorch safety with bisphenol-curedcompounds. VPA No. 3 is hygroscopic—a loss ofcompound scorch safety can occur if exposed to water,including high-humidity conditions. VPA No. 3 does notaffect peroxide-cured compound cure rate.

A slight bloom will be noted on preforms and press-cured
articles containing VPA No. 1, which disappears during
the oven post-cure.
VPA No. 1 has no effect on original or heat-aged
stress/strain properties and only a minor effect on hightemperature compression set. Two parts of VPA No. 1 ina standard formulation with Viton™ E-60C will increaseshrinkage approximately 0.4% after an oven post-cure of
24 hr at 232 °C (450 °F).

VPA No. 3 has no effect on original or heat-aged stress/
strain properties, including compression set resistance.
Addition of 1.6 phr to Viton™ E-60 increases shrinkage
by 0.3%.

VPA No. 2
VPA No. 2 is recommended as an extrusion aid for avariety of extruded goods, such as tubing and complex
profiles. It can be premixed with other compounding2

Viton™

Fluoroelastomers

Table 2. VPA No. 1 Processing Aid in Viton™ E-60C and Viton™ E-430
Compound2A

2B2C2D2EViton E-60C100100100——™

Viton E-430———

100

100

MT Carbon Black

3030301010High-Activity MgO

3333

3Calcium Hydroxide

66666

VPA No. 1

—

12—

2™

Stock Properties
Mooney Scorch, MS at 121 °C (250 °F)
Units, minimum
Time to 5-pt rise, min

33

33

30

2218

1 pt in 45 min

2 pt in 45 min

3 pt in 45 min

0 pt in 45 min

0 pt in 45 min

ODR at 177 °C (351 °F), Microdie, 1° Arc, 12 min
ML, in·lb

0.8

0.7

0.7

0.5

0.4

ts0.23 [ts2], min

2.7

2.5

2.2

3.7

3.2

tc90, min4.9

4.7

4.1

6.1

5.3

MH, in·lb

5.5

5.6

5.4

3.4

3.2

Garvey Die Extrusion (Cold feed, cold screw, barrel extension—24 °C [75 °F], barrel—66 °C [151 °F], head—104 °C [219 °F], die—135 °C [275 °F],screw speed—35 rpm)
Rate, cm/min

386

Die Swell, g/cm
Stock Temperature, °C (°F)

391

406

——

1.7

1.7

1.8——

124 (255)

124 (255)

121 (250)

113 (235)

110 (230)

Appearance (Ratings range from 1 = very smooth to 4 = very rough)Back Edge

43

2

2

1

Surface33211Feather Edge

44221

Vulcanizate Properties
Press Cure: 10 min at 177 °C (351 °F) ; Post-Cured: 24 hr at 232 °C (450 °F)
Mold Shrinkage, % (linear)—25 mm x 200 mm x 6 mm bar
After Press Cure

2.7

2.7

2.8

—

—

After Oven Cure

3.2

3.4

3.6

—

—

100% Modulus, MPa

5.9

6.4

5.7

1.6

1.6

Stress/Strain at 23 °C (73 °F)—OriginalTensile Strength, MPa

13.1

13.3

12.9

11.7

12.2

Elongation at Break, %200190

190

370

330

Hardness, Durometer A

7677755958

1.7

1.7

Stress/Strain at 23 °C (73 °F)—After Aging 70 hr at 275 °C (527 °F)
100% Modulus, MPa

5.0

5.0

4.5

Tensile Strength, MPa

11.4

11.5

11.0

9.8

10.9

Elongation at Break, %200

220200320320Hardness, Durometer A

75767559

60

Compression Set Resistance, Method B, O-Rings, %, 25.4 mm x 4.0 mm
70 hr at 24 °C (75 °F)

1098

1.1

970 hr at 200 °C (392 °F)

1415161215336 hr at 200 °C (392 °F)

34343736

3970 hr at 232 °C (450 °F)

39414241

463Viton™

Fluoroelastomers

Table 3. VPA No. 2 Processing Aid in Viton™ E-60C
Compound3A3B3CViton E-60C

100100100

MT Carbon Black

303030High-Activity MgO

333Calcium Hydroxide

666

VPA No. 2—

1233

34

34

Time to 5-pt rise, min

1 pt in 45 min

2 pt in 45 min

3 pt in 45 min

Time to 10-pt rise, min

—

——

™

Stock Properties
Mooney Scorch, MS at 121 °C (250 °F)
Units, minimum

ODR at 177 °C (351 °F), Microdie, 1° ArcML, N·m

0.8

0.8

0.8

ts0.232 [ts2], min

2.7

2.92.9tc90, min

4.9

5.1

5.2MH, N·m

5.5

5.4

5.3

Garvey Die Extrusion (Cold feed, cold screw, barrel extension—24 °C [75 °F], barrel—66 °C [151 °F], head—104 °C [219 °F], die—135 °C [275 °F],screw speed—35 rpm)
Rate, cm/min

386

419

427

Die Swell, g/cm

1.7

1.7

1.7

Stock Temperature, °C

124113110

Back Edge

43

1Surface

33

2Feather Edge

43

1

Appearance (Ratings range from 1 = very smooth to 4 = very rough)Vulcanizate Properties
Press Cure: 10 min at 177 °C (351 °F); Post-Cured: 24 hr at 232 °C (450 °F)
Mold Shrinkage, % (linear)—25 mm x 200 mm x 6 mm bar
After Press Cure

2.7

2.7

2.7

After Oven Cure

3.2

3.4

3.6

100% Modulus, MPa

5.9

6.9

7.1

Tensile Strength, MPa

13.1

12.4

12.4

Elongation at Break, %200200

190

Hardness, Durometer A76

75

75

100% Modulus, MPa

5.0

5.7

6.9

Tensile Strength, MPa

11.4

11.0

11.7

Elongation at Break, %200

190

180

Hardness, Durometer A75767870 hr at 24 °C (75 °F)

1010970 hr at 200 °C (392 °F)

142024336 hr at 200 °C (392 °F)

34424470 hr at 232 °C (450 °F)

3950

53

Stress/Strain at 23 °C (73 °F)—Original

Stress/Strain at 23 °C (73 °F)—After Aging 70 hr at 275 °C (527 °F)

Compression Set Resistance, Method B, O-Rings, %, 25.4 mm x 4.0 mm

4Viton™

Fluoroelastomers

Table 4A. VPA No. 3 Processing Aid in Viton™ E-45 and Viton™ E-60
Compound

4A

4B

4C

4D

4E

4F

Viton™ E-45

97.8

97.8

97.8

———

Viton E-60

—

——

96.9

96.9

96.9

MT Black (N908)

303030303030™

High-Activity MgO333333

Calcium Hydroxide

66666

6

Viton™ Curative No. 20

1.26

1.26

1.26

1.65

1.65

1.65

™

Viton Curative No. 30

2.8

2.8

2.8

444

VPA No. 3

—

0.8

1.6

—

0.8

1.6

Stock Properties
Mooney Scorch, MS at 121 °C (250 °F)—Original
Units, minimum

32333440

4242

Time to 10-pt rise, min>30>30>30>30>30>30

Mooney Scorch, MS at 121 °C (250 °F)—After Aging 7 days at 38 °C (100 °F) and 100% Relative Humidity
Units, minimum

4040

42484748Time to 10-pt rise, min12121112129ODR at 177 °C (351 °F), Microdie, 3° Arc, 12 min
ML, N·m

1.2

1.2

1.2

1.4

1.5

1.6

ts0.232 [ts2], min

3.4

2.8

2.3

3.1

2.4

2.3

tc90, min

7.8

7.2

6.7

6.4

5.6

5.0

MH, N·m

8.8

8.6

8.4

13.8

13.9

13.6

Vulcanizate Properties
Press Cure: 10 min at 177 °C (351 °F); Post-Cured: 24 hr at 232 °C (450 °F)
Mold Shrinkage, % (linear)—25 mm x 200 mm x 6 mm bar
After Press Cure

2.6

2.72.62.6

2.6

2.6

After Oven Cure

2.9

3.2

3.3

3.0

3.2

3.3

100% Modulus, MPa

4.3

4.6

4.5

5.9

6.3

6.2

Tensile Strength, MPa

12.2

11.5

11.8

12.1

12.6

12.5

Elongation at Break, %265

245

250

205

200

200Hardness, Durometer A

7271

7075

7373

Stress/Strain at 23 °C (73 °F)—Original

Stress/Strain at 23 °C (73 °F)—After Aging 70 hr at 275 °C (527 °F)
100% Modulus, MPa

3.0

3.3

3.3

4.7

4.7

4.9

Tensile Strength, MPa

6.4

6.4

6.5

7.9

7.4

8.0

Elongation at Break, %315305315200190

200Hardness, Durometer A

8080808483

84

Compression Set Resistance, Method B, O-Rings, %, 25.4 mm x 4.0 mm
70 hr at 23 °C (73 °F)

18181899970 hr at 200 °C (392 °F)

2424241818

18

70 hr at 232 °C (450 °F)

4444

44

3535355

Viton™

Fluoroelastomers

Table 4B. VPA No. 3 Processing Aid in Viton™ B-50
Compound4G4H4I

Viton B-50

9696

96

MT Black (N908)

303030High-Activity MgO

333™

Calcium Hydroxide

666Viton™ Curative No. 20

333

Viton™ Curative No. 30

444VPA No. 3—

0.81.6Units, minimum

525153Time to 10-pt rise, min>30>30>30

Stock Properties
Mooney Scorch, MS at 121 °C (250 °F)—Original

Mooney Scorch, MS at 121 °C (250 °F)—After Aging 7 days at 38 °C (100 °F) and 100% Relative Humidity
Units, minimum

575555Time to 10-pt rise, min1412101.4

1.6

1.6ODR at 177 °C (351 °F), Microdie, 3° Arc, 12 min
ML, N·m
ts0.232 [ts2], min

3.3

2.7

2.3tc90, min

7.1

6.5

5.8MH, N·m

9.89.39.2

Vulcanizate Properties
Press Cure: 10 min at 177 °C (351 °F); Post-Cured: 24 hr at 232 °C (450 °F)
Mold Shrinkage, % (linear)—25 mm x 200 mm x 6 mm bar
After Press Cure

2.6

2.6

2.5

After Oven Cure

3.1

3.3

3.4

100% Modulus, MPa

6.2

6.2

6.3

Tensile Strength, MPa

11.8

12.1

12.9

Elongation at Break, %205

205

220Hardness, Durometer A

76

7776

3.4

3.4

3.4

Stress/Strain at 23 °C (73 °F)—Original

Stress/Strain at 23 °C (73 °F)—After Aging 70 hr at 275 °C (527 °F)
100% Modulus, MPa
Tensile Strength, MPa

5.9

6.0

5.9

Elongation at Break, %280

290315

Hardness, Durometer A

8482

8170 hr at 23 °C (73 °F)

15151570 hr at 200 °C (392 °F)

4144

41

Compression Set Resistance, Method B, O-Rings, %, 25.4 mm x 4.0 mm*Atochem, Buffalo, NY

6Viton™

Fluoroelastomers

Test Procedures
Property Measured

Test Procedure

Compression Set

ASTM D3955, Method B (25% deflection)

Compression Set—Low Temperature

ASTM D1299, Method B (25% deflection)

Compression Set, O-Rings

ASTM D1414

Hardness

ASTM D2240, durometer A

Mooney Scorch

ASTM D1646, using the small rotor. Minimum viscosity and time to a1-, 5-, or 10-unit rise are reported.

Mooney Viscosity

ASTM D1646, ten pass 100 °C (212 °F) and 121 °C (250 °F)

ODR (vulcanization characteristics measured with an oscillating disk cure meter)

ASTM D2084

Property Change After Oven Heat-Aging

ASTM D573

Stress/Strain Properties
100% Modulus
Tensile Strength
Elongation at BreakASTM D412, pulled at 8.5 mm/s (20 in/min)

Stiffness, Torsional, Clash-Berg

ASTM D1043

Temperature RetractionASTM D1329

Volume Change in Fluids

ASTM D471

Note: Test temperature is 24 °C (75 °F), except where specified otherwise

For more information, visit Viton.com
The information set forth herein is furnished free of charge and based on technical data that Chemours believes to be reliable. It is intended for use by persons having technical skill, at their own
discretion and risk. The handling precaution information contained herein is given with the understanding that those using it will satisfy themselves that their particular conditions of use present
no health or safety hazards. Because conditions of product use are outside our control, Chemours makes no warranties, express or implied, and assumes no liability in connection with any useof this information. As with any material, evaluation of any compound under end-use conditions prior to specification is essential. Nothing herein is to be taken as a license to operate under or arecommendation to infringe any patents.
NO PART OF THIS MATERIAL MAY BE REPRODUCED, STORED IN A RETRIEVAL SYSTEM OR TRANSMITTED IN ANY FORM OR BY ANY MEANS ELECTRONIC, MECHANICAL, PHOTOCOPYING, RECORDING OR OTHERWISEWITHOUT THE PRIOR WRITTEN PERMISSION OF CHEMOURS.

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Replaces: VTE-H71132-00-E0710
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