Elastomers—Rubbers and TPEs

This data can be used with GRANTA MI or CES Polymer Selector to support rational selection, enterprise material strategy, and positioning (technical and economic) of these materials.

This page provides more detailed information on the MaterialUniverse elastomers data. For general information on MaterialUniverse, see here 

On this page:

Why would you be interested?

Do you:

  • Design products containing elastomers?
  • Need to understand elastomers from a materials selection perspective?
  • Need the best cost / performance trade-off?
  • Need to assess traditional rubbers against newer thermoplastic elastomers?

Elastomers are special materials.  They combine mechanical strength with exceptional flexibility, conformability, and 'bounce back'. They find applications in functions where no other materials will do: tires, seals, springs, hinges, couplings, sheathing, vibration mounts, bags, films, soft-touch coatings.  They fall into two camps: rubbers, chemically cross-linked polymers that offer the highest elastomeric performance, and TPEs (thermoplastic elastomers), which have the advantage of melt-processability and design flexibility.  Rubbers are sometimes described as 'traditional elastomers', having been in widespread use for over 100 years.  TPEs are relatively new with use, applications, and varieties continuing to grow rapidly.


The problem

Rubbers: these have infinitely variable recipes based on around 25 main rubber polymer types, numerous carbon black and non-black filler variants, oil extenders, and small amounts of vulcanizing agents, accelerators, and stabilizers, etc.  Some recipes are published in '‘rubber formularies", many others are proprietary to the rubber compounder.  The terminology, chemistry, and cookery can be intimidating to design engineers—opportunities for innovation and improvement are inevitably missed.

TPEs: these are sold in well-defined grades for molding, just like other thermoplastics.  However, while designers are aware of brands such as Santoprene (TPV), many are unaware that Santoprene is only one of around 15 major TPE categories.   TPEs are a fast-moving and, to many, confusing field.  Even plastics experts have a hard time agreeing on common terminology, or what is a TPE and what is not.

Rubber and TPEs together:  it is common to look at replacing rubber with TPE when redesigning parts because of the design flexibility of TPE: but when is it truly economic, and what are the performance pitfalls?


The Granta solution

Granta has created a database that enables comparison of all different types of rubber and TPE on a like-for-like basis for a full set of design criteria: cost, mechanical, physical, thermal, electrical, optical, durability, chemical resistance, biocompatibility, etc.  This has never been done before.

For design engineering, the elastomer data supports decisions on which materials to use, and how to use them.  Materials producers use the data to anaylze the technical and economic performance of their materials, and position them against competitors.


How does the elastomer data help in design?

Design requirement
How the elastomer data helps
So what?
Exhaustive, reproducible, auditable search of rubber and TPE types
Coverage of nearly all rubber and TPEs chemistries that are commercially available.  They are categorized by chemical composition and hardness. See summary in the tables below.
With so many rubbers and TPEs on offer it is valuable to select the most appropriate early in any design project. 

For elastomer producers: Competitive positioning of elastomer grades requires all possible alternatives.
“What is the lowest cost material that delivers the required performance?”
Price of each resin ($/lb, Euro/Kg, etc) derived using Granta’s material price model.  Quarterly updating is available.
Different elastomers vary widely in price.  Prices needed for 'cost per unit of function' comparisons (MI:Optimize or CES Polymer Selector calculate these).
Medical use;
food contact use
When purchased with the Medical MaterialUniverse data:

ISO 10993-1 or USP Class VI grades.
FDA 22 CFR 177, EEC/EU, NSF, or BfR grades.

Sterilizability rankings for: ethylene oxide (EtO), steam autoclave, radiation (gamma, electron-beam).
Aid regulatory approval of device (US 501k) or drug (NDA).

Required for food contact use of any plastic part.

Disposables must withstand 1 or 2 sterilization cycles, other equipment repeated sterilization.
Mechanical: strength, stiffness, and more
The full range of mechanical response properties of materials universe—strengths, stiffnesses, hardnesses.

Also, Strength at 100% & 300% elongation, Tear Strength, Abrasion Rate, Compression Set at 23, 70, 100 deg C.
Elastomers are very ‘non-linear’ materials—additional parameters are provided to characterize their stress-strain response. 

Compression Set measures the elastomer’s recovery after compression:  0% = perfect; 100% = none.

Tear strength and abrasion rate characterize resistance to two common elastomer failure modes: tearing and wear.
Service temperature range
Maximum service temperature.

Minimum service temperature.

ASTM D2000 temperature rating.  
In general, TPEs offer more limited operating ranges than rubbers.  The attributes are there to screen out materials subject to low temperature embrittlement or high temperature loss of elastic recovery.
Transparency for functional and/or aesthetic reasons
Ranked as opaque, translucent, transparent, or optical quality.
Elastomers range from opaque through to optical quality transparency.
Durability to fluids and chemicals
Resistance ratings of materials to 190 specific chemicals. ASTM D2000 oil swell rating.
Important when rubber or TPE part will be exposed to chemicals. Elastomers vary hugely in their chemical resistance.  None are resistant to everything.  Some are very poor in fuels and oils, others are poor in polar media.
Barrier or permeability use
Permeability to: Oxygen (O2), Water vapour (H2O), Carbon dioxide (CO2)
Important for packaging, fluid containers, etc.  Elastomers offer orders of magnitude differences in permeability.
Others
Electrical properties (conductivity, dielectric constant, dissipation factor, dielectric strength…); flammability (UL94…); water and humidity adsorption; processing properties (molding temperature, …), eco-properties (carbon footprint, embodied energy…)
These are all factors affecting material selection and elastomer properties relating to them vary widely.


Details of the rubber data

Chemistry
Abbreviation
Full name
Common name or trade name
Hydrocarbon, unsaturated
NR
Natural rubber
‘Rubber’
IR
Synthetic poly-isoprene rubber
Natsyn
SBR
Styrene butadiene rubber
Buna SL
BR
Butadiene rubber
Buna BL
IIR
Butyl rubber
Butyl
CIIR, BIIR
Chloro- and bromo- butyl rubber
Halobutyl
Hydrocarbon, saturated
EPM/EPDM
Ethylene propylene (diene) rubber
Nordel
Nitrile
NBR
Nitrile butadiene rubber
Buna-N
HNBR
Hydrogenated nitrile rubber
Therban
XNBR
Carboxylated nitrile rubber
Nipol
NBR+PVC
Nitrile-PVC blend
Nipol Polyblend
Chlorocarbon, unsaturated
CR
Polychloroprene rubber
Neoprene
Chlorocarbon, saturated
CSM
Chloro-sulfonated polyethylene and alkylated chloro-sulfonated polyethylene
Hypalon
Acsium
CM
Chlorinated polyethylene
Tyrin
Acrylate
ACM
Acrylic rubber
Hytemp
AEM
Ethylene acrylic copolymer rubber
Vamac
Vinyl acetate
EVM
Ethylene vinyl acetate copolymer rubber
Levapren
Fluorocarbon
FKM
Fluoro elastomer
Viton
FFKM
Perfluoro elastomer
Kalrez
FEPM
Tetrafluoroethylene propylene elastomer
Aflas
Polysulfide
TM
Polysulfide rubber
Thiokol
Polyether
CO/ECO
Epichorohydrin rubber
Hydrin
GPO
Polyproylene oxide rubber
Polyurethane
AU
Polyurethane elastomer, ester-based
Adiprene
EU
Polyurethane elastomer, ether-based
Silicone
MVQ
Silicone rubber
Silastic, Elastosil
PMVQ
Phenyl methyl silicone rubber
FMVQ
Fluoro silicone rubber
Other
PNB
Polynorbornene rubber
Norsorex

Rubber presents a special problem in building a system for like-for-like material comparison: rubber compound recipes have infinite variability and are rarely standardized.  We solve this problem by representing the commercially available classes of rubber shown above by their raw gum vulcanizates and typical cured compounds (mostly carbon black filled) with broad compositional ranges.


Details of the TPE data

In the TPE section of the data, there are approximately 80 'master grades' of TPE summarizing over 3,000 commercially available grades.  Linked datasheets for the commercial grades are normally included in most packages, via the Granta CAMPUS Plastics and Prospector Plastics (previously known as 'IDES Plastics') data modules.

Chemistry
Abbreviation
Full name
Alternative names
Example brand
Olefinic
TPO
Thermoplastic Polyolefin Elastomer
TPE-O, PEO, TEO (thermoplastic elastomer, olefinic)
Dexflex
TPV
Thermoplastic Vulcanizate
Santoprene
POE/POP
Polyolefin Elastomer/Plastomer (ethylene and propylene-based)
Engage, Versify
Styrenic
SBS
Styrene Butadiene Styrene Block Copolymer
TPS, SBC (styrenic block copolymer), TES (thermoplastic elastomer, styrenic), TPE-S
Kraton
SIS
Styrene Isoprene Styrene Block Copolymer
Kraton
SEBS
Styrene Ethylene Butylene Styrene Block Copolymer
Kraton
Vinyl
PVC-elastomer
Polyvinyl Chloride Elastomer
Flexalloy
Urethane
TPU
Thermoplastic Polyurethane Elastomer (Polyester, Aromatic)
TPUR, TPE-U
Desmopan
Thermoplastic Polyurethane Elastomer (Polyether, Aromatic)
Elastollan
Thermoplastic Polyurethane Elastomer (Polyether, Aliphatic)
Tecoflex
Polyester-polyether
TEEE
Thermoplastic Elastomer, Ether-Ester
TPC-ET, TPE-E, COPE (copolyether-ester elastomer)
Hytrel, Arnitel
Polyamide-polyether
PEBA
Polyether Block Amide
TPA, TPE-A, COPA
Pebax
Other
MPR
Melt Processable Rubber
Alcryn
Also in the MaterialUniverse data module are other soft thermoplastics that are sometimes referred to as elastomeric or that compete with TPEs for the same applications.   These include: flexible PVC, EVA (ethylene vinyl acetate), EMA/EEA/EBA (ethylene acrylates), and ionomer.