NBR (Nitrile Rubber) vs PBT (unfilled): 0% composition overlap. Significantly different materials serving different application areas.
NBR (Nitrile Rubber) vs PBT (unfilled)
Side-by-side chemical composition and mechanical property comparison.
Overview
NBR (Nitrile Rubber)
Nitrile butadiene rubber (Buna-N) — THE oil and fuel resistant elastomer. ACN content (18-50%) determines the oil resistance vs low-temp flexibility tradeoff. Higher ACN = better oil resistance but stiffer at low temp. The most widely used seal material worldwide. Used for O-rings, fuel hoses, gaskets, hydraulic seals, oil seals, and nitrile gloves. Not suitable for ozone, UV, or polar solvents (ketones, esters). HNBR variant for higher heat resistance.
PBT (unfilled)
Polybutylene Terephthalate — semi-crystalline polyester with fast crystallization (short cycle times), very low moisture absorption (0.15%), excellent dimensional stability, and good electrical properties. Key advantage over PA: properties nearly independent of humidity. Trade names include Ultradur (BASF), Celanex/Crastin (Celanese/DuPont), Valox (SABIC), Arnite T (DSM). Used for electrical connectors, relay housings, automotive sensors, and any precision part in humid environments.
| NBR (Nitrile Rubber) | PBT (unfilled) | |
|---|---|---|
| Material Number | — | — |
| Category | Polymers | Polymers |
| Standard | ISO 37 | ISO 10350 |
Chemical composition (wt%) — Pro
| Element | NBR (Nitrile Rubber) | PBT (unfilled) | Overlap |
|---|---|---|---|
| Butadiene | 50–82% | — | — |
| Acrylonitrile (ACN) | 18–50% | — | — |
| Base Polymer (Polybutylene Terephthalate) | — | 99–99.9% | — |
Mechanical properties — Pro
| Property | NBR (Nitrile Rubber) | PBT (unfilled) | Unit |
|---|---|---|---|
| Tensile Strength | 7–24 | 50–65 | MPa |
| Elongation | 200–600 | 50–100 | % |
| hardness_shore_a | 40–90 | — | Shore A |
| Density | |||
| continuous_service_temp | |||
| Yield Strength | |||
| Elastic Modulus | |||
| Melting Point | |||
| Glass Transition Temp (Tg) | |||
| Water Absorption (24h) | |||
| Tensile Strength | |||
| Tensile Modulus | |||
| Elongation at Break | |||
| Charpy Impact (notched) | |||
| Density | |||
| Melting Point | |||
| HDT/A (1.8 MPa) | |||
| Water Absorption (24h) |
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Sign up free — 3 comparisons/day freeCompatibility Assessment
NBR (Nitrile Rubber) and PBT (unfilled) have significantly different compositions (0% overlap). These materials are not interchangeable and serve different application areas.
Automated assessment based on composition analysis
Frequently Asked Questions
Is NBR (Nitrile Rubber) the same as PBT (unfilled)?
NBR (Nitrile Rubber) and PBT (unfilled) have a 0% composition overlap. They are generally not directly interchangeable.
Can I replace NBR (Nitrile Rubber) with PBT (unfilled)?
Generally not recommended. The compositions differ significantly (0% overlap). These materials have different alloying concepts and are intended for different applications.
What is the difference between NBR (Nitrile Rubber) and PBT (unfilled)?
The main differences are in the following elements: overall alloying content. NBR (Nitrile Rubber) is a Polymers grade, while PBT (unfilled) is a Polymers grade.
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Data provided for reference only. Always verify against the applicable specification for critical applications.
All data is for reference only. Equivalents indicate similarity, not identity. Always verify against the applicable specification for safety-critical applications. materialref.com accepts no liability for decisions based on this data.