PRODUCT DEVELOPMENT INFORMATIONVOLUME 2ISSUE 11MARCh 2013

FLUOROCARBON RUBBER(FKM RUBBER) – ITS OVERVIEW
Fluorocarbon Rubbers, designated by FKM (earlier it was designated as FPM), is the Sspecialised Rubber, which
are very stable, characterised by extreme Heat, Fire Resistance, Resistance to Oxidation, Ozone, swelling tooils and solvents and unusually high chemical resistance.
As per the ASTM D2000/SAE J200 system of classification, FKM & FFKM (PerFlourinated fluorocarbonrubber) occupies the top performance range, in the rubber category & is designated as HK – for FKM & KK
for FFKM.

FKM Rubber is made as Co-polymer, Ter-polymer and Sspecial blends to meet the rigorous end requirements,depends on the choice of the Monomers.

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PRODUCT DEVELOPMENT INFORMATION

Monomers being used for the manufacturing of FKM rubbers are as follows:f Vinylidene Fluoride (VF2)CH2=CF2

f Hexa FluoroPropylene(HFP)

CF2=CF-CF3

f Tetra FluoroEthylene(TFE)

CF2=CF2

f PerFluoroMethyl Vinyl Ether(PFMVE)/

CF2=CF-O-CF3PerfluoroAlkyl VinylEther(PAVE)f 1-HydroPentaFluoroPropylene(HPFP)CHF=CF-CF3

f TriFluoroChloroEthylene(TFClE)

CFCl=CF2

And other monomers likef Ethylene (E)f Propylene(E)are also used for the special type of FKM Rubber
Depends on the combination of the monomers, different sub-type/sub-classification of FKM rubber is being
manufactured world-wide, viz.
f CO-POLYMER
f TER-POLYMER
f TER-POLYMER – PEROXIDE CURABLE
f SPECIAL LOW TEMPERATURE PEROXIDE CURABLE
f BASE RESISTANT
f PERFLUORO ELASTOMER – FFKM

Based on the ASTM D1418, FKM RUBBER is classified as 5 types as follows:
TYPE 1

CO-POLYMER OF Hexafluoropropylene & Vindylidenefluoride 3 HFP+VF2

TYPE 2

TER-POLYMER of Tetrafluoroethylene, vinylidenefluoride &hexafluoroprpylene 3 TFE+VF2+HFP

TYPE 3

TER-POLYMER of Tetrafluoroethylene, fluorinated vinylether &vinylidenefluoride 3 TFE+PFMVE / PAVE+VF2

TYPE 4

TER-POLYMER of Tetrafluoroethylene, propylene & vinylidene
fluoride 3TFE+P+VF2TYPE 5

PENTA-POLYMER of Tetrafluoroethylene, hexafluoropropylene,vinylidenefluoride, ethylene & a fluorinatedalkylvinylether 3TFE+HFP+VF2+E+PFMVE/PAVE
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PRODUCT DEVELOPMENT INFORMATIONFor FFKM(PERFLUOROELASTOMER) the combination of the monomers are Tetrafluoroethylene,
perfluoromethyl vinyl ether and a special cure-site monomer 3 TFE+PFMVE/PAVE+X
FKM Rubber is cured by Diamines, Bisphenol A/organophosphonium salt, Peroxide(only peroxide curablegrades) and TAIC.
FKM RUBBERS are available COMMERCIALLY as GUM Rubbers (Curatives needs to be added duringcompounding), Cure incorporated ones (only acid acceptors, fillers & processing aids need to be added),

The commonly used ingredients are as follows:
FILLER – BLACK

MT BLACK, FURNACE BLACK like SRF, FEF,HAF(at limited dosage), AUSTIN BLACK,
conductive black, graphite,...

FILLER-WHITE

Barium Sulfate, Diatomaceous Silica,
Calcium Meta silicate, , Rutile TiO2, calcium
carbonate, ppt. Silica, micronized PTFE,....

PROCESSING AIDS

PETS, PE WAX, VEGETABLE WAX, Amine
based, Zinc Stearate, Low volatile plasticisers
are not used in FKM. Low molecular weight
FKM in liquid form can be used.

ACID ACCEPTORS

MgO, CaO, ZnO, Pb3O4 & with Ca(OH)2,CURING SYSTEM used in FKM RUBBER:Curing Type

Characteristics

DIAMINE CURING SYSTEM

General purpose cure system

BISPHENOL A / Organophosphonium salt

For Improved compression set resistance andmost commonly used system nowadays.

PEROXIDE

For peroxide curing type FKM, good resistance toacid, steam & amine based media.

FOR FFKM

Depends on the curing point, following curesystem is being used
• For Phenoxy group 3 Bisphenol AF• For Bromine/Iodine 3 TAIC
• For CN group 3 Tin based via Triazine
formation.

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POST-CURING OF FKM:
All the grades of FKM needs to be post-cured and for peroxide based grades a post-curing of 4-8 hrs. @230 deg.C is sufficient & for other types of curing a minimum of 15/16 hr. – 24 hr. curing cycle is essential for thestabilisation of curing. Post-cure increases the heat stability of the rubber because during the post-curing
cycle, heat-stable aromatic cross-links are formed and it will give good compression set resistance.
Generally post curing is done at the temperatures of 205deg.C, 232 deg.C and 250 deg.C&above. It is better tokeep the products in the post curing cycle, by starting the oven temperature either from room temperatureor from around 90 deg.c in a step of 20 – 25 deg.C/hr, till the desired post curing temperature is reached, toachieve better properties in the FKM products.

Application of FKM:
In the high-temperature resistance and corrosive chemicals and hot-oil resistance requirements, also as abinder for powdered rocket fuels, insulators in the low-voltage & frequency applications, etc.... in Automotive,
Aerospace, Chemical & Processing, Oil field/Mining, Semicon industries.

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The Heat resistance of the FKM rubber is about 200 deg.C for continuous service, However, with increasing
temperature the service life gets shortens approximately as follows:

TEMPERATURESERVICE LIFE

230 oC

3000 hr.

260oC1000 hr.

290oC

240 hr.

315oC

48 hr.

FKM GRADES OF TECNOFLON are as follows:Tecnoflon ® Bisphenol Curable

Tecnoflon ® Bisphenol Curable

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TECNOFLON – FKM & FFKM PRODUCT SELECTION GUIDE:

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PRODUCT DEVELOPMENT INFORMATIONVOLUME 2 • ISSUE 11 • MaRCH 2013

KINDLY NOTE: TECNOFLON IS MANUFACTURED BY M/S. SOLVAY SOLEXIS.
7 of 7Ram Charan Company | Samson Tower, 403, L – Pantheon Road, 6th Floor, Egmore, Chennai 600 008. Tamil Nadu, India.
Phone : +91 44 4353 9040 • Fax : +91 44 4330 7050 • Email : mktg@ramcharan.org • Website : www.ramcharan.org
Mumbai | 098212 16311
rps@ramcharan.org

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