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Elastomers - Rubbers and TPEs

Data covering elastomers (both rubbers and thermoplastic elastomers) is available within Granta’s MaterialUniverse data module. It 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.

Rubber and elastomeric components

On this page:

Why would you be interested?
The problem
The Granta solution
How does the elastomer data help in design
Details of rubber data
Details of TPE data

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.

The rubber section of the Granta’s MaterialUniverse data module has been completely revised for the 2008 release and a number of new elastomer chemistries added. The TPE section was first released in 2007 and updated in 2008.

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:EMO 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
Chlorocarbon, saturated	CM	Chlorinated polyethylene	Tyrin
Acrylate	ACM	Acrylic rubber	Hytemp
Acrylate	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
Polyether	GPO	Polyproylene oxide rubber
Polyurethane	AU	Polyurethane elastomer, ester-based	Adiprene
Polyurethane	EU	Polyurethane elastomer, ether-based	Adiprene
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 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.