Materials & Polymer Engineering
Engineering Elastomers & Polymer Selection Guide
Elastomer Landscape
Major elastomer families span general-purpose rubbers, oil-resistant nitriles, high-temperature fluoropolymers, silicone systems, polyurethane elastomers and thermoplastic elastomers.
Elastomer selection is governed by polymer chemistry, temperature, pressure, media, mechanical loading, dynamic conditions and required service life.
The polymer is the starting point — the compound is the engineering solution.
General Purpose
NR / IR / SBR / BR
Dynamic performance, resilience, abrasion
Tyres, mounts, vibration and general engineering
Nitriles
NBR / XNBR / HNBR
Oil resistance; wear; heat/ageing
Hydraulic, oil and dynamic seals
Ethylene-Propylene
EPDM / EPM
Water, steam, ozone, weather
Water, steam and outdoor sealing
Fluoropolymers
FKM / FFKM / FEPM
Heat, fuel and chemical resistance
Aerospace, automotive and chemical
Silicone Systems
VMQ / FVMQ / PVMQ
Temperature flexibility; fuel
Aerospace, medical, electrical
Acrylic & Epichlorohydrin
ACM / AEM / ECO
Hot oil, air, fuel, gas barrier
Automotive and fuel systems
Polyurethane Elastomers
PU / TPU
Wear, tear, load capacity
Hydraulics, pneumatics, rollers
Thermoplastic Elastomers
TPE / TPV
Thermoplastic elastomeric processing
Automotive and injection moulding
Temperature & Media Compatibility
Temperature capability must be evaluated together with the actual fluid or media.
A polymer may behave differently in air versus oils, fuels, steam or aggressive chemicals. Temperature capability alone is not enough — the operating media, pressure and exposure duration must be considered together with the material temperature range.
Screening, Not Spec
Representative values in this guide are for material screening only. Actual service limits depend on grade, formulation, cure system, media, pressure, exposure duration and component design.
Comprehensive Polymer Library
Screening ratings for oil/fuel, water/steam, ozone and wear across the Vajra material range.
| Polymer | Temp °C | Oil/Fuel | Water/Steam | Ozone | Wear | Key Characteristic | Applications |
|---|---|---|---|---|---|---|---|
| NRNatural Rubber / Polyisoprene | −50 to +80 | Poor | Fair | Poor | Excellent | Fatigue, resilience, tear | Mounts, flex elements, tyres |
| IRSynthetic Polyisoprene Rubber | −50 to +80 | Poor | Fair | Poor | Very good | NR-like consistency | Technical mouldings |
| SBRStyrene-Butadiene Rubber | −50 to +100 | Poor | Fair | Fair | Excellent | Cost and abrasion | Tyres, mats, conveyors |
| BRPolybutadiene Rubber | −70 to +100 | Poor | Fair | Fair | Excellent | Resilience, low temperature | Tyres, impact products |
| NBRAcrylonitrile-Butadiene Rubber | −30 to +100/120 | Excellent | Good | Poor | Very good | Oil resistance | O-rings, oil/hydraulic seals |
| XNBRCarboxylated Acrylonitrile-Butadiene Rubber | ≈−30 to +120 | Excellent | Good | Poor | Exceptional | Strength, tear, wear | Heavy-duty seals, wipers |
| HNBRHydrogenated Acrylonitrile-Butadiene Rubber | −30 to +150 | Excellent | Good | Excellent | Excellent | Heat, oil, ageing | Automotive, aerospace seals |
| CRPolychloroprene / Neoprene | −40 to +120 | Good | Good | Excellent | Good | Balanced resistance | Bellows, hoses, mounts |
| EPDMEthylene-Propylene-Diene Rubber | −50 to +150 | Poor* | Excellent | Excellent | Good | Water, steam, ozone | Water/steam and weather seals |
| IIRIsobutylene-Isoprene / Butyl | −50 to +120 | Fair | Excellent | Excellent | Fair | Very low gas permeability | Vacuum/gas seals |
| FKMFluoroelastomer / Fluorocarbon | −20 to +200/220 | Exceptional | Moderate | Excellent | Good | Fuel, oil, heat, chemicals | Aerospace, automotive |
| FFKMPerfluoroelastomer | −20 to +260/325 | Exceptional | Excellent | Excellent | Fair | Extreme chemical/thermal | Chemical, semiconductor |
| FEPMTetrafluoroethylene-Propylene | ≈−10 to +200/230 | Excellent | Excellent | Excellent | Good | Steam and chemicals | Oil & gas, chemical |
| VMQMethyl-Vinyl Silicone | −60 to +200/230 | Fair | Good | Excellent | Poor | Temperature flexibility | Aerospace, medical |
| FVMQFluorosilicone | −60 to +175/200 | Excellent | Fair | Excellent | Poor | Fuel + low temperature | Aerospace fuel systems |
| PVMQPhenyl-Methyl-Vinyl Silicone | ≈−90 to +200 | Fair | Good | Excellent | Poor | Extreme low-temperature | Aerospace/cryogenic |
| ACMPolyacrylate Rubber | −20 to +150/175 | Excellent | Fair | Excellent | Fair | Hot-oil resistance | Transmission/engine seals |
| AEMEthylene-Acrylic Rubber | −40 to +175 | Very good | Fair | Excellent | Good | Hot air + oil | Turbo hoses, powertrain |
| ECOEpichlorohydrin Copolymer | −40 to +135/150 | Very good | Good | Excellent | Good | Oil + gas barrier | Fuel hoses, diaphragms |
| CSMChlorosulfonated Polyethylene | −40 to +120/150 | Good | Good | Excellent | Good | Weather + chemicals | Cable jackets, linings |
| AUPolyester Polyurethane | −30 to +100/120 | Excellent | Fair | Good | Exceptional | Wear, tear, load | Hydraulic seals, rollers |
| EUPolyether Polyurethane | −50 to +100/120 | Very good | Excellent | Good | Exceptional | Wear + hydrolysis | Hydraulic/pneumatic seals |
| TPUThermoplastic Polyurethane | ≈−50 to +100/120 | Good | Good | Good | Excellent | Wear + thermoplastic | Seals, wheels, mouldings |
| TPVThermoplastic Vulcanizate | ≈−50 to +135 | Fair–Good | Good | Excellent | Good | EPDM-like + thermoplastic | Automotive weather seals |
* EPDM is generally unsuitable for mineral oils and hydrocarbon fuels. Verify exact media and compound.
Compound Engineering
The polymer is only the beginning.
Final elastomer performance depends on polymer grade, molecular characteristics, fillers, reinforcement, plasticizers, cure chemistry, crosslink density, antioxidants, antiozonants, hardness, processing and post-cure. Two components made from the same polymer family can therefore perform very differently.
| Variable | Engineering Effect |
|---|---|
| Polymer grade | Base chemical and physical behaviour |
| ACN content in NBR | Oil resistance versus low-temperature flexibility |
| Carbon black / reinforcement | Strength, hardness, wear and conductivity |
| Plasticizer | Flexibility and low-temperature behaviour |
| Cure system | Crosslink density, compression set and heat ageing |
| Peroxide vs sulphur cure | Heat resistance and dynamic behaviour |
| Antioxidants / antiozonants | Ageing and environmental resistance |
| Hardness | Sealing force, extrusion and wear |
| Surface treatment | Friction, stick-slip and assembly |
| Processing | Dimensional accuracy, bonding and consistency |
Application-Driven Material Selection
Matching the requirement to the preferred polymer families.
| Requirement | Preferred Families | Engineering Note |
|---|---|---|
| Mineral oil | NBR / XNBR / HNBR / FKM | Temperature and pressure determine final selection |
| High-wear oil seal | XNBR / HNBR / PU | Prioritize abrasion, tear and extrusion resistance |
| Hot oil | HNBR / FKM / ACM / AEM | Check ageing and fluid additives |
| Water / hot water | EPDM | Excellent water and weather resistance |
| Steam | EPDM / FEPM / FFKM | Compound and steam conditions are critical |
| Aviation fuel | FVMQ / FKM | Aerospace qualification required |
| Extreme chemicals | FFKM / FEPM / FKM | Check exact concentration |
| Extreme low temperature | PVMQ / VMQ / FVMQ | Flexibility and Tg are critical |
| Gas / vacuum | IIR / CIIR / ECO / FKM | Permeability and outgassing matter |
| Heavy abrasion | PU / XNBR / NR | Wear mechanism and hardness matter |
| Hydraulic sealing | NBR / XNBR / HNBR / PU | Pressure, speed and fluid drive selection |
| Automotive powertrain | HNBR / FKM / ACM / AEM | Heat, oil and ageing dominate |
| Aerospace sealing | FVMQ / FKM / HNBR / FFKM | Application-specific qualification |
NBR vs XNBR vs HNBR
Comparing oil-resistant nitrile systems for selection.
| Characteristic | NBR | XNBR | HNBR |
|---|---|---|---|
| Chemistry | Acrylonitrile + butadiene | Carboxylated NBR | Hydrogenated NBR |
| Primary objective | Oil resistance + economics | Mechanical strength + wear | Heat + ageing + oil |
| Oil resistance | Excellent | Excellent | Excellent |
| Tensile / tear | Very good | Exceptional | Excellent |
| Abrasion | Very good | Exceptional | Excellent |
| Heat resistance | Good | Good | Excellent |
| Ozone/weather | Poor | Poor | Excellent |
| Dynamic sealing | Very good | Excellent | Excellent |
| Best reason to use | General oil sealing | High-wear/high-load sealing | High-temperature oil sealing |
XNBR is especially valuable when abrasion, tear and mechanical loading dominate. HNBR is generally selected when oil resistance must be combined with higher heat, oxidation and ozone resistance.
Aerospace & Defence Selection
Candidate elastomers for demanding mission applications.
| Requirement | Candidate Elastomers | Primary Considerations |
|---|---|---|
| Aircraft fuel | FVMQ / FKM | Fuel compatibility, low temperature, qualification |
| Hydraulic systems | HNBR / FKM / XNBR | Pressure, temperature, wear, fluid compatibility |
| Engine oil | FKM / HNBR / ACM | High-temperature ageing |
| Extreme chemicals | FFKM | Maximum chemical resistance |
| Cryogenic / low temperature | PVMQ / VMQ / FVMQ | Low-temperature flexibility |
| Dynamic flex elements | NR / specialist systems | Fatigue and resilience |
| Rocket / missile actuator seals | NBR / HNBR / FKM / specialist | Mission-specific qualification |
| Rocket / missile flex seals | Specialist NR / elastomer systems | Fatigue, bonding, geometry and mission environment |
A polymer family should never be represented as automatically qualified for aerospace or defence service. Qualification must be tied to the specific compound, geometry, process and mission environment.
Property Screening
Relative screening scores are qualitative engineering indicators, not laboratory test data.
Polymer-to-Performance Workflow
Thirteen engineering steps from operating environment to validated production.
Vajra Engineering Positioning
At Vajra, elastomers are treated as engineered material systems rather than commodity materials. We evaluate the application environment, identify the appropriate elastomer family, select the polymer grade, engineer the compound and manufacture the component to the required geometry and performance specification. Our objective is not simply to select a rubber. It is to engineer the right material system for the application.
Material expertise
NR | IR | SBR | BR | NBR | XNBR | HNBR | CR | EPDM | IIR | CIIR | BIIR | FKM | FFKM | FEPM | VMQ | FVMQ | PVMQ | ACM | AEM | ECO | CSM | AU | EU | TPU | TPE | TPV
Technical Disclaimer
This guide is a general engineering reference and does not constitute a material qualification, specification or guarantee of service performance. Final selection should be validated through application-specific testing and applicable customer, ASTM, ISO, aerospace, defence or regulatory requirements.