Information Source - edited from "KEVIN-TECH" aka Kevin Bebb's
Technical Notes - LDI Ltd. in-house proprietary , since 1963.
The compound ingredient percentages are chosen by LDI Ltd. to cause
similar physical properties, and from advice by the Rubber &
Plastics Research Association (aka RAPRA.) and others. :-
In the uncured / un-polymerized state,:
To be easily transfer-injectable over distances greater than 3x the
item diameter, without the use of long oil alkids etc. for
In the cross linked / polimerized state, to have :-
1. Elongation at break in excess of 600%,
2. UTS greater than 2000 psi (140 bar)
3. IRH Shore "A" scale hardness 55-60,
4. Good compression set resistance for seal-points.
5. The use of "non-leaching" plasticizer
IE that crosslinks within the cured material.
6. No Sulfur.
MATERIAL TO CHOOSE FROM.
Note - "LDI" are not compatibility engineers .
Be sure to check your selection against the "O" rings Seal, gasket,
valve diaphragm, pump packings that have proved satisfactory for
Errors and Omissions Excepted. "E&OE"
ASTM ELASTOMER DESIGNATIONS WITHIN LDI Ltd (MembranoFlex)
"FFKM", "PIB" , "EP" "EPDM" "EPR" , "ECO", "FKM", "CSPE", "NR",
"CR", "NBR", "MQ, VMQ, PVMQ, FVMQ," "T Also ST". Etcetera
Aflas TM Perfluoro-elastomer
Temperatures 450 Degrees F
tear resistance POOR
Typical Uses Sour Service - H2S
More Detail http://www.darcoid.com/includes/tetrafluoroethylene
aka "PIB" , newer Halobutyl
Not easily "bondable".
tear resistance fail
Typical Uses Automobile inner tubes
Other Oxygen permeation resistance
More Detail http://en.wikipedia.org/wiki/Butyl_rubber
Nordel TM EPCAR TM , VISTALON TM
Generic - EPT Ethylene Propylene Terpolymer Peroxide Cured
aka EP,"EPDM" (D M Diamine-Monomer not understood - it is no longer
a monomer when polimerized),
aka also "EPR".
Temperatures 300 F
tear resistance good
Typical Uses water based, wide applications (not OILS, Hydrocarbons)
Other Good abrasion resistance, low cost
More Detail http://www3.interscience.wiley.com/journal/104021283/
Temperatures High and Low
tear resistance fair
Typical Uses resistance to fuel oil,
More Detail http://www.primasil.com/polymers/text.asp?PageId=42
Trade names Fluorel TM, Viton TM
Common variants "A", "B", "B50","E60C", "GS"
tear resistance BAD
Typical Uses, result of much hype, Viton TM Thought to be a panacia.
Other Expensive, elongation / elasticity very poor, & NOT for low
temperature use at all.
More Detail http://www.knovel.com/web/portal/browse/display?_EXT_
Hypalon TM (Per Dupont is Obselecent)
aka "CSPE" & synthetic rubber (CSM)
Temperatures :- extremes
Typical Uses Chemical Resistance
More Detail http://en.wikipedia.org/wiki/Hypalon
Natural Rubber "Indico"
tear resistance good , ebrasion resistance good
Typical Uses ambient temperature hose
Other Highly elastic - diametric opposite to fluoro-elastomers.
More Detail http://www.rubber-stichting.info/
Neoprene generic "polychloroprene"
Temperatures Good high temp aging resistance
tear resistance Fair
Typical Uses Automotive parts
Other resists some specialty chemicals
aka "NBR" (in a low grade aka "Buna N")
Common Variants :
a. Low temp Nitrile - to negative 70 50 F? C?
b. High Temp Nitrile -
c. Hydrogenated ("HNBR") Increase properties , and some CO2
d. FDA ingredient versions, White,
Temperatures according to variant
tear resistance, Fair, abrasion resistance good
Typical Uses Hydrocarbon liquids, fluid power hydraulics
Other Reasonable price
More Detail http://www.ashtabularubber.com/nitrile-page.html
Silicone Rubber - wide varieties
aka MQ, VMQ, PVMQ
Temperatures up to 500 F
hot tear resistance BAD
Typical Uses external environments UV resistance, and medical
Other difficult to inflate without tearing for tool release
More Detail http://www.dowcorning.com/content/rubber/silicone-
aka "T" "ST"
Temperatures Good for ultra low
tear resistance poor, suffers compression set
Typical Uses Solvents, rocket fuel seals
Other Difficulties with mold (mould) release.
GENERAL NOTE - CAVEAT A typical elastomer compound may have at
The named Elastomer, an activator, an accelerator, the curing -
cross linking agent ,
a plasticizer (PREFERABLY cross-linking) anti ozonant, fillers
typically chimney /
furnace black, etc . Up to a dozen constituents.
The performance of any one of the above available synthetic
"rubbers" depends on
the experience of the compound formulator and a full disclosure by
the end user of
all the details of the actual application.
NON ELASTOMERS - IE "PLASTOMERS".
aka LDI "DW series"
PTFE that has been raised to 730 F gell temperature
converting all PTFE sintered prcipitate particles
into one homogeneous plastic.
Imparts some resilience and enable flexibility when
combined with concentric wave shaped corrugations.
Servicability as PTFE
Availability membranes up to 305mm diameter, 320 in3
5.25 Liter .
aka LDI "DF series"
has bonded high temp EPT backing to provide some resilience -
to impede the "cold flow" of PTFE. and slow the rate of
permeation experienced with virgin PTFE (aka "Teflon" TM) because
of its sintered particulate nature.
Availability Membranes up to 454mm diameter, 1000 in3
16.4 liter .
Trade names / trade marks, noted here in "TM" are the property of
their respective technology owners. Predominantly "Dupont Dow Elastomers"