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Rubber & Elastomers•General-Purpose Diene Rubbers•
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Natural Rubber (NR)

Primary Designation:ASTM NR
Aliases:
Polyisoprene RubberGum RubberIndia RubberHevea Rubber

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Data Completeness:0 composition elements and 1 condition-specific property values cataloged.
Omitted fields represent unverified properties. "Missing is better than invented."

Key Engineering Properties

Representative source rows, qualified by their reported conditions. Inspect the tables below for all values, limits, and source notes.

Service Temp Range
-50°C to 80°CContinuous Limit
Continuous service typically -50°C to +8...

Engineering Summary

Natural Rubber (NR) is a high-molecular-weight cis-1,4-polyisoprene elastomer derived from Hevea brasiliensis latex. It features extraordinary tensile strength, superior tear resistance, high mechanical resilience, and exceptional dynamic fatigue life. Under high tensile extension, natural rubber undergoes strain-induced crystallization, self-reinforcing against crack propagation. Formulations exhibit poor resistance to petroleum hydrocarbon oils, fuels, and non-polar solvents, and require chemical antiozonants to mitigate atmospheric ozone cracking.

Natural Rubber (NR) Documented Applications

  • ›Heavy-duty pneumatic commercial truck and aircraft tire treads and carcasses
  • ›Dynamic elastomeric anti-vibration engine mounts, seismic bridge bearings, and marine dock fenders
  • ›High-resilience industrial conveyor belts, gum rubber chute linings, and slurry pump impellers
  • ›Flexible surgical gloves, medical catheters, and pharmaceutical closures
  • ›High-elasticity power transmission belts, shock cords, and dynamic couplings

Recognized Aliases

Source-backed commercial trade name and short designations cataloged in canonical data.

Polyisoprene RubberGum RubberIndia RubberHevea Rubber

Elastomer Technical Profile • Natural Rubber (NR)

ASTM D1418: NRISO 1629: NRASTM D2000: Type AA

Polymer backbone: Natural cis-1,4-polyisoprene. Thermoset and cast elastomer mechanical, thermal, and chemical behavior depends strongly on compounding ingredients, crosslink density, and curing system.

Key Engineering Advantages

  • •Exceptional tensile strength and tear resistance among general-purpose elastomers due to strain-induced crystallization
  • •Strain-induced crystallization arrests crack propagation under dynamic fatigue cycling
  • •Exceptional resilience and minimal internal heat build-up under dynamic flexure
  • •Outstanding low-temperature flexibility maintained down to -50°C
  • •Excellent adhesion to fabric plies, brass-plated steel cords, and metallic structural inserts

Engineering Limitations & Risks

  • •Severe degradation and swelling upon exposure to petroleum oils, hydrocarbon fuels, and non-polar solvents
  • •Rapid surface cracking under atmospheric ozone attack unless compounded with antiozonant waxes
  • •Degrades rapidly at sustained operating temperatures exceeding 80°C (176°F)
  • •Susceptible to oxidative aging and thermal softening (reversion) during prolonged sulfur cure

Thermal Operating Limits & Service Profile

Min Continuous-50°C
Max Continuous80°C
Max Intermittent / PeakNot specified

Note: Continuous service typically -50°C to +80°C (-58°F to +176°F) per Parker ORD 5700 Section II (Figure 2-3). Conventional sulfur cures undergo network reversion and modulus loss above ~70°C–80°C (Maurice Morton Rubber Technology 3rd Ed., pp. 24–30); EV and semi-EV cure systems retard reversion up to ~100°C. ASTM D2000 Type AA callouts define 70h accelerated heat-aging test requirements for classification rather than continuous service ratings.

Chemical & Environmental Media Compatibility (Engineering Selection Guide)

Parker ORD 5700 Selection Ratings
Ratings represent manufacturer engineering fluid selection guidance (Parker ORD 5700 / producer design manuals). They do not substitute for batch-specific ASTM D471 / ISO 1817 laboratory immersion testing under service temperature, pressure, and dynamic stress.
Water & Aqueous GlycolsResistant to ambient water, dilute salt solutions, and ethylene glycol
EXCELLENT
Dilute Acids & AlkalisResistant to non-oxidizing dilute acids; attacked by nitric and chromic acids
GOOD
Atmospheric Ozone & UVRequires chemical antiozonants (6PPD) and paraffinic wax bloom to prevent cracking
POOR
Petroleum Oils & GreasesRapid volumetric swelling, softening, and mechanical disintegration
NOT RECOMMENDED
Hydrocarbon Fuels (Gasoline/Diesel)Severe solvent extraction and massive swelling
NOT RECOMMENDED
Ketones & AcetonePolar solvents cause moderate swelling
FAIR

Compounding & Physical Property Context

Compounding Dependency: Natural rubber properties vary widely with compounding formulation, carbon black grade/loading (N220 to N774), sulfur-to-accelerator ratio, and antioxidant systems. Unfilled gum rubber exhibits high elongation (>700%) with lower modulus; highly reinforced industrial compounds achieve higher stiffness with reduced elongation.

Gas & Fluid Permeability: Moderate gas permeability; significantly higher air permeability than butyl rubber (IIR).

Abrasion Endurance: Excellent dynamic abrasion resistance against coarse slurries and impingement; slightly inferior to SBR in sliding highway tire friction.

Tear Resistance: High ASTM D624 Die C tear strength due to instantaneous strain-induced crystallization at the crack tip. (Die C angle geometry measures initiation and propagation combined; results are not directly comparable to trouser tear ASTM D624 Die T / ISO 34-1 Method A).

Compression Set (ASTM D395): Good compression set resistance at ambient to 70°C; EV cure systems improve high-temperature set retention.

Natural Rubber (NR) Specifications & Designations

Standard Designations & Applicable Specifications — Semantically classified designations distinguishing primary standard identifiers, commercial trade names, and applicable specification references.

Direct Standard DesignationsDIRECT DESIGNATION
3 Primary Identifiers
Scroll horizontally for full designation data
SystemIdentifierStandard System NameClassification Notes & Provenance
ASTMPRIMARYNRASTM D1418 Nomenclature—Ref: Standard Practice for Rubber and Rubber Latices—Nomenclature (ASTM D1418-22) / Rubber and latices—Nomenclature (ISO 1629:2013)
ISONRISO 1629 Nomenclature—Ref: Standard Practice for Rubber and Rubber Latices—Nomenclature (ASTM D1418-22) / Rubber and latices—Nomenclature (ISO 1629:2013)
ASTM-D2000Type AAASTM D2000 Classification SystemClassified under ASTM D2000 as Type AA (defined by 70h accelerated heat-aging test at 70°C; accelerated test temperatures serve material classification and do not constitute continuous service ratings).Ref: Standard Classification System for Rubber Products in Automotive Applications (ASTM D2000-21 / SAE J200:2021)
Recognized Commercial Aliases & Trade NamesCOMMON ALIAS
4 Listed
Scroll horizontally for full alias classifications
Recognized Name / AliasClassificationTechnical Usage & Context
Polyisoprene RubberCommercial AliasColloquial or commercial industry synonym
Gum RubberColloquial AliasColloquial or commercial industry synonym
India RubberHistorical AliasColloquial or commercial industry synonym
Hevea RubberCommercial AliasColloquial or commercial industry synonym
Applicable Specifications & Product Form ReferencesSPECIFICATION REFERENCE
3 Applicable Standards
Scroll horizontally for full standard specifications
Standards BodySpecification CodeSpecification Title / ScopeRelationship Type
ASTM InternationalASTM D1418Standard Practice for Rubber and Rubber Latices—NomenclatureSTANDARD · Edition: ASTM D1418-22Specification Reference
ISOISO 1629Rubber and latices — NomenclatureSTANDARD · Edition: ISO 1629:2013Specification Reference
ASTM InternationalASTM D2000Standard Classification System for Rubber Products in Automotive ApplicationsSTANDARD · Edition: ASTM D2000-21Specification Reference
Engineering Notice: Applicable specifications establish manufacturing requirements, dimensional tolerances, and test criteria for specific product forms (e.g. bus bar, wire, plate, pipe). They represent applicable technical standards, not alternative or equivalent alloy grades.

Natural Rubber (NR) Mechanical Properties

Contextual Mechanical Properties & Tempers: Engineering strength, ductility, and hardness values grouped by product form, temper, and section thickness. Mechanical properties are contextual and not isotropic averages.

Showing 1 of 1 conditions
Scroll horizontally for all conditions & tempers
Product FormTemper / ConditionSection SizeTensile (UTS)Yield StrengthElongationShear StrengthFatigue StrengthHardness (Scales Preserved)Status
Standard Product FormStandard Formulated Vulcanizate (Carbon Black Reinforced) · 70 °C
Source values and qualifiers
Compression Set (22h at 70°C): 15–35 % (RANGE)Compression set measured under 25% constant mechanical deflection after 30 min recovery.ASTM D395 Method B / ISO 815-1Parker Hannifin Corporation, Engineered Materials Group — Parker Hannifin Corp. Catalog ORD 5700 (2018/2023), Section II (Basic O-Ring Elastomers: Table 2-2 & Figure 2-3), Section VII (Compatibility Tables) / ASTM D395-18 Method B
———————VERIFIED
Hardness Integrity Notice: Rockwell B (HRB), Rockwell F (HRF), and Superficial 30T (HR30T) scales are reported on their measured scales without cross-scale mathematical conversion.
Source: See fact-level citations

Natural Rubber (NR) Processing & Fabrication

Machining, joining, forming, and thermal processing ratings cataloged from the cited authoritative technical reference.

Source: Maurice Morton (Ed.), Springer Science+Business Media

Machinability

Cryogenically machined with liquid nitrogen (-196°C) to freeze elastomer below glass transition temperature (Tg ≈ -70°C) for precision lathe turning, grinding, or CNC waterjet cutting with abrasive garnets.

Heat Treatment & Working Ranges

Vulcanized via accelerated sulfur cure systems (typically 140°C to 160°C for 5 to 30 minutes) or semi-EV/EV (efficient vulcanization) formulations to optimize reversion resistance and minimize compression set.

Forming & Cold Working

Masticated on two-roll mills or internal mixers (Banbury) to reduce Mooney viscosity prior to compounding. Readily molded via compression, transfer, or injection molding, and shaped via calendar sheet rolling and multi-cavity extrusion.

Natural Rubber (NR) Equivalent & Comparable Grades

Comparable Grades & Cross-References: Carefully classified cross-reference relationships for Natural Rubber (NR). Comparable does not mean equivalent.

Scroll horizontally for relationship classifications & comparisons
Related MaterialFamilyRelationship ClassificationMetallurgical Notes & DifferencesStatusAction
Styrene-Butadiene Rubber (SBR)rubber-and-elastomersCommonly ComparedNR provides higher tensile strength, tear resistance, and resilience due to strain crystallization; SBR offers lower cost and superior dry sliding abrasion resistance.Materials serve different design priorities (e.g. higher strength vs superior corrosion resistance or cost).VERIFIEDSide-by-Side Compare →
Ethylene Propylene Diene Rubber (EPDM)rubber-and-elastomersNearest AlternativeNR is selected for high dynamic resilience and tear resistance; EPDM is selected when outdoor ozone, UV, hot water, or steam exposure would degrade NR.Design parameters (weldability, hardenability, fatigue limit) must be re-evaluated for the specific application.VERIFIEDSide-by-Side Compare →

Related Engineering & Metallurgy Guides

Contextual technical guides explaining degradation mechanisms, testing methodologies, and selection criteria relevant to Natural Rubber (NR).

Material Selection18 min read

Types of Rubber: Elastomer Classification, Chemical Resistance & Selection Guide

Selecting the correct rubber is not a matter of choosing a generic flexible polymer—it requires matching molecular backbone chemistry to service temperature, chemical media polarity, dynamic fatigue, and compression set. This engineering guide classifies the 11 primary elastomer families, detailing their ASTM D1418 / ISO 1629 designations, mechanical performance envelopes, and rigorous selection algorithms.

Author: MatGrades Materials Engineering GroupRead Guide →
Material Selection17 min read

What is EPDM Rubber? Properties, Chemistry, Roofing vs Engineering Specifications

EPDM (Ethylene Propylene Diene Monomer) is the global benchmark elastomer for outdoor weathering, hot water, and automotive cooling systems. Its exceptional resistance to atmospheric ozone and steam degradation stems from an entirely saturated polyalkylene backbone with crosslinkable double bonds located exclusively on pendant side groups. This guide breaks down the chemical physics, curing kinetics, and standards governing EPDM specification.

Author: MatGrades Materials Engineering GroupRead Guide →
Material Selection18 min read

Natural Rubber vs Synthetic Rubber: Resilience, Fatigue, Chemistry & Industrial Trade-offs

Despite over a century of synthetic polymer synthesis, natural rubber remains indispensable in modern heavy engineering. Its unique ability to undergo instantaneous strain-induced crystallization grants it dynamic tear strength and fatigue endurance that synthetic random copolymers cannot replicate. However, when service conditions introduce petroleum fuels, atmospheric ozone, or temperatures exceeding 80°C, synthetic elastomers become mandatory. This guide examines the macromolecular physics and industrial trade-offs governing selection.

Author: MatGrades Materials Engineering GroupRead Guide →

Sources

Sources & Provenance Trail: Authoritative reference publications, standards specifications, and data registers cited across this material record.

ASTM International, ISO & Elastomer Engineering Technical CommitteesParker O-Ring Handbook (Catalog ORD 5700) & Elastomer Engineering Selection Guide
Development BenchmarkSTANDARDS ORG

Global engineering seal benchmark establishing continuous operating temperature envelopes (Figure 2-3), elastomer property comparisons (Table 2-2), ASTM D395 Method B compression set benchmarks, and manufacturer engineering fluid compatibility selection ratings (distinguished from raw laboratory immersion coupons).

Issuing Body: Parker Hannifin Corporation, Engineered Materials GroupRevision: ORD 5700 (2018/2023)View Source Record ↗
ASTM International, ISO & Elastomer Engineering Technical CommitteesStandard Practice for Rubber and Rubber Latices—Nomenclature (ASTM D1418-22) / Rubber and latices—Nomenclature (ISO 1629:2013)
STANDARDS ORG

Authoritative international nomenclature defining rubber acronyms and classification families.

Issuing Body: ASTM International & ISO Technical Committee ISO/TC 45 (Rubber and Rubber Products)Revision: ASTM D1418-22 / ISO 1629:2013View Source Record ↗
ASTM International, ISO & Elastomer Engineering Technical CommitteesStandard Classification System for Rubber Products in Automotive Applications (ASTM D2000-21 / SAE J200:2021)
STANDARDS ORG

Standardized classification system establishing Type and Class designations and line callouts for vulcanized rubber compounds.

Issuing Body: ASTM International & SAE International Technical CommitteesRevision: ASTM D2000-21View Source Record ↗
ASTM International, ISO & Elastomer Engineering Technical CommitteesRubber Technology (3rd Edition, Maurice Morton, Ed.) & Processing Specifications
STANDARDS ORG

Authoritative scientific treatise detailing cis-1,4 strain crystallization kinetics, network polysulfidic crosslink reversion at >70°C–80°C in conventional sulfur cures vs semi-EV stabilization, and SBR reinforcement.

Issuing Body: Maurice Morton (Ed.), Springer Science+Business MediaRevision: 3rd EditionView Source Record ↗
Intellectual Property & Provenance Notice: Mat Grades cites technical literature from recognized industry associations and standards organizations. Underlying technical standards and publication data remain the intellectual property of their respective issuing organizations.