vamac_ultra_lt

DuPont? Vamac? Ultra LT

ETHYLENE ACRYLATE ELASTOMERS TECHNICAL BULLETIN

DuPont? Vamac? Ultra LT compound with no plasticizer has a

Tg of –40°C and it maintains that Tg even after aging in air for

six weeks at 150°C or one week at 175°C. With a plasticizer the

initial Tg can be as low as –54°C.

The fluid resistance of the Vamac? Ultra LT compounds is not

as good as the G/GLS compounds. The fluid resistance can be

improved by blending with Vamac? G. The blends with G

will have intermediate low temperature performance and

intermediate fluid resistance.

The polymer is typically cured with a diamine. It can also be

cured with a peroxide. The gum elastomer has a low level of

a processing aid and a nominal specific gravity of 1.03. The

polymer has a mild acrylic odor and the storage stability of the

polymer is excellent.

Major Performance Properties and Applications

Cured compounds made from Vamac? Ultra LT have a good

combination of properties including a wide operating window

for end use temperatures. A compound with no plasticizer has

a temperature window of –40°C up to 165°C and the compound

can withstand short term temperature spikes up to 200°C. The

low temperature properties can be improved by the addition of

a plasticizer and with 20 phr of plasticizer the initial Tg is about

–54°C. The cured compounds are typically rated as class E for

heat resistance using the ASTM D2000 system and this means

that they will pass a heat rating test of 70 hours at 175°C

(347°F). They will also pass a six week air aging requirement at

temperatures as high as 165°C (329°F).

The fluid resistance of a cured compound depends on the

carbon black and plasticizer level. A typical value for volume

swell in IRM 903 fluid after aging for 168 hr at 150°C (302°F)

is about 90%.

The compounds made from Vamac? Ultra LT have much lower

volume swell in transmission fluid and in engine oils. The volume

swell in Service Fluid 105 (1 week/150°C) is about 50% and the

volume swell in ASTM #1 (1 week/150°C) is about 7%.

DuPont?Vamac? Ultra LT (formerly Vamac?VMX 4017) is an

ethylene methyl acrylate based polymer with an acidic cure

site monomer. It has improved low temperature properties

compared to DuPont?Vamac? G or DuPont? Vamac? GLS.

Compounds made from Vamac? Ultra LT have similar heat

resistance, compression set, CSR and dynamic properties

when compared to compounds made from Vamac? G or GLS.

Most of the newer engine oils, transmission fluids, and high temperature greases are more synthetic and have higher aliphatic content than conventional test oils. The newer fluids also have much lower or no aromatic content. The volume swell in IRM903 may not be a good predictor for performance in the newer fluids.

The compression set values for compounds based on DuPont?Vamac? Ultra LT were measured after one week at 150°C and the range in values is from 20 to 40%. The results depend on the curative package, the level of carbon black and the level

of plasticizer.

CSR (Compressive Stress Relaxation) tests run on Vamac?

Ultra LT compounds show very good properties for six weeks at 150°C in engine oils. The percent retained sealing force is a relatively high value and this is probably due to the relatively high volume swell. The DuPont? Vamac? Ultra LT compounds have higher values compared to the DuPont? Vamac? G compounds which in turn have higher retained sealing forces compared to Vamac? GLS compounds.

These properties of Vamac? Ultra LT compounds make them well suited for a wide range of automotive applications.

Some of these are molded boots, powertrain seals and gaskets, rocker cover seals, transmission oil coolant hoses, power steering hoses, turbo-charger hoses, crankcase ventilating tubes, coverings for fuel and coolant hoses, O-rings, grommets and crankshaft dampers.

Vamac? Ultra LT is a halogen free polymer and does not decompose to give off corrosive gases when exposed to flame. It can be used for flame retardant, low-smoke, non-halogen wire and cable jackets and in non-halogen, low smoke flooring. Vamac? Ultra LT compounds are well suited for injection, transfer or compression molding. They also can be extruded.

Handling Precautions

Vamac? Ultra LT contains small amounts of residual methyl acrylate monomer and residual n-butyl acrylate monomer so adequate ventilation should be provided during mixing and processing to prevent worker exposure to the acrylate monomers. Additional information may be obtained in the Vamac? Ultra LT Material Safety Data Sheet (MSDS) and the bulletin “Safe Handling and Processing of Vamac? and Vamac?Compounds”. Both are available from the DuPont Packaging and Industrial Polymer sales office serving you. The MSD sheet is also available at the following web site,

https://www.wendangku.net/doc/0a4545050.html,. Product Properties

Property Target Value Method Mooney Viscosity, ML

(1+4) at 100°C (212°F) 11 ASTM D 1646 Total Volatile Matter, wt% < 0.40 Internal DuPont Test Form, mm (in) Bale Size is nominally: Visual inspection

560 x 370 x 165 (22 x 15 x 7)

Color Clear to opaque with Visual inspection

slight variations in color

Compound and Vulcanizate Properties — DuPont? Vamac? Ultra LT compared to

DuPont? Vamac? G

T able 1 shows the formulation and rheological properties of four different compounds. Two are based on Vamac? Ultra LT where one compound has no plasticizer and the other has

20 phr of plasticizer. The other two compounds are based on Vamac? G and have 0 or 20 phr of plasticizer. The black level was adjusted to give a hardness of about 62 Shore A. The compounds were mixed on a small laboratory mixer and then press cured for five minutes at 175°C followed by a four post cure at the same temperature. The rheology results are shown in Table 1.

The compound formulations are 100 phr of polymer, black level and plasticizer level as indicated, 1.5 phr Stearic acid, 1.0 phr Vanfre VAM, 0.5 phr Armeen 18D, 2 phr Naugard 445, 1.25 phr Diak #1, 2.0 phr DOTG, 2.0 phr DPG.

Cured Properties

The cured properties of the four compounds are shown in

T able 2. Included are several different test methods for deter-mining low temperature properties and each test method gives a different result. For example, the Vamac? Ultra LT compound with no plasticizer has a low temperature value as high as

–32°C (Tan delta from DMA at 1 Hz) and as low as –55°C (static O-Ring). It is very important to match up the low temperature test for a compound to the actual requirements of the end use. The Vamac? Ultra LT compound with no plasticizer has about the same initial low temperature properties as the Vamac? G compound with 20 phr plasticizer. However, after aging in air or in a test fluid the Vamac? Ultra LT compound with no plasticizer is significantly better than the Vamac? G compound with 20 phr of plasticizer. A problem with any plasticized compound is

the loss of plasticizer during heat aging. It is very difficult to find a plasticizer with good low temperature properties and

low volatility.

T able 1

T able 2

Cured Properties

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DuPont Singapore PTE Ltd. (65) 273-2244

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DuPont (Australia) Ltd. (3) 9721 5900

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DuPont do Brasil, S.A. 55 (11) 7266 8542

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DuPont Canada, Inc.

(800) 268-3943/(905) 821-5953

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DuPont de Nemours Int’l. S.A. (022) 717 51 11

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DuPont Kabushiki Kaisha (81-3) 5521 8500

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DuPont, S.A. de C.V . (52) 55 57 22 1000

United States

DuPont Packaging and Industrial Polymers (302) 774-1161 (800) 438-7225

Tg by DSC for blends of DuPont ? Vamac ? G and DuPont ? Vamac ? Ultra LT before and after heat aging for one week at 175°C.

The graph below shows the change in Tg after heat aging for one week at 175°C. As the plasticizer level increases there is a signficant drop in Tg for the initial Tg. However, after heat aging for one week at 175°C there is only a slight benefit for the high plasticizer levels. Heat aging for one week at 175°C is approximately equal to six weeks at 150°C.

Materials Used in Formulations and Test Fluids — General composition and Supplier

Material

Chemical Composition

Supplier Polymer

DuPont ? Vamac ?

G Ethylene Acrylic Elastomer DuPont Vamac ? Ultra LT Ethylene Acrylic Elastomer DuPont

Release Aids

Armeen 18D Octadecyl Amine Akzo Nobel Vanfre VAM Complex Organic phosphate ester R.T. Vanderbilt Stearic Acid

Anti-Oxidant

Naugard 445 Diphenyl Amine

Uniroyal Chemical Plasticizer

TP-759 Mixed Ether/Ester Plasticizer Rohm & Haas

Fillers

N550 Carbon Black

Curatives

Diak #1 Hexamethylene Diamine DuPont Performance

Carbamate

Elastomers DOTG Di-ortho-tolyl Guanidine DPG

Diphenyl Guanidine Test Fluids

ASTM #1 Aliphatic Test Fluid ASTM Test

Monitoring Center IRM 903

Test Fluid

Service Fluid 105 Service Fluid 105 ASTM Test

Monitoring Center

The test methods used in the work are shown below.Rheology

Mooney Viscosity D 1646Mooney Scorch D 1646MDR

D 5289 Physicals Hardness

D 2240Tensile, Elongation, Mod D 412Tear, Die C D 624Fluid Aging

D 471Compression Set D 395Tg by DSC D 3418Aging in Air

D 573Temperature of Retraction

D 1329

The DMA test was run at 1 Hertz with a temperature sweep of

–150°C up to 150°C using a dual cantilever fixture. The static O-ring test is described in “New, Improved Processing PMVE-Peroxide Cured Types of Viton ?”, Paper number 30 at the Fall 2001 ACS Rubber Symposium, R.D. Stevens and D.F . Lyons.

Copyright ? 2007 DuPont. The DuPont Oval Logo, DuPont ?, The miracles of science ?, and Vamac ? are registered trademarks or trademarks of E.I. du Pont de Nemours and Company or its affiliates. All rights reserved.

Viton ? is a registered trademark of DuPont Performance Elastomers.K-17478 (10/07) Printed in the U.S.A .

The technical data contained herein are guides to the use of DuPont resins. The advice contained herein is

based upon tests and information believed to be reliable, but users should not rely upon it absolutely for specific applications because performance properties will vary with processing conditions. It is given and accepted at user’s risk and confirmation of its validity and suitability in particular cases should be obtained independently. The DuPont Company makes no guarantees of results and assumes no obligations or liability in connection with its advice. This publication is not to be taken as a license to operate under, or recommendation to infringe, any patents.CAUTION: Do not use in medical applications involving permanent implantation in the human body. For other medical applications, see DuPont Medical Caution Statement, H-50102.