Rubber Material Engineering Guide
Natural Rubber (NR): Properties, Applications & Selection Guide
Natural rubber, standardized as NR, is valued for high resilience, tensile and tear strength, abrasion performance and dynamic fatigue resistance. Those strengths do not make every NR compound suitable for heat, ozone, petroleum oils, fuels or regulated contact. Raw-rubber grade, compound formulation, vulcanization, reinforcement, part geometry and actual service conditions must be reviewed together.
NR Fundamentals
What Is Natural Rubber (NR)?
NR is a natural elastomer whose rubber hydrocarbon is predominantly cis-1,4-polyisoprene. Commercial material is most commonly obtained from Hevea brasiliensis latex and supplied either as dry natural rubber or as preserved latex concentrate for different manufacturing routes.
“NR” is not a complete compound specification. Source, raw-rubber grade, dirt and volatile matter, nitrogen and ash, plasticity or viscosity, mastication, fillers, plasticizers, protective additives, cure package and processing history all influence the finished rubber. Two parts labeled “NR 60 Shore A” can therefore differ in rebound, tear, fatigue, heat aging, compression set and ozone resistance.
NR is normally considered when high elasticity, resilience, strength, wear performance or repeated deformation dominates the design. Selection must still begin with load, motion, temperature, environment, medium and expected life rather than the assumption that a natural material is suitable for every industrial duty.
NR is usually a strong candidate when
- The part needs high resilience, elastic recovery, tensile or tear strength.
- Dynamic flexing, impact, abrasion or vibration performance is a primary requirement.
- The component is a wheel, roller, spring, coupling, mount, diaphragm or reinforced flexible part.
- The exact compound and product can be validated for the defined load, motion and environment.
NR needs another look when
- The part has continuous contact with petroleum oils, fuels or swelling solvents.
- Long-term heat or outdoor ozone exposure exceeds the selected compound’s validated capability.
- Low compression set at elevated temperature is more important than rebound or dynamic strength.
- A named food, medical, low-protein, sustainability or other approval is required but no qualified grade is defined.
Performance Profile
What Are the Key Properties of Natural Rubber?
NR is best understood as a high-elasticity and high-dynamic-performance elastomer family. Properly formulated compounds can combine resilience, tensile and tear strength, abrasion resistance, fatigue resistance, vibration performance and useful tack. Its limitations in ozone, heat and petroleum fluids remain part of the selection decision.
Elasticity & Resilience
Selected NR compounds recover efficiently after deformation and can provide high rebound with comparatively low hysteresis in suitable dynamic designs.
Tensile & Tear Strength
NR can develop high tensile and tear performance, especially when compound design and strain-induced crystallization support the actual stress state.
Abrasion & Wear
NR is widely evaluated for wheels, rollers, tires and wear parts. Abrasive type, slip, load, heat generation and surface conditions still determine service life.
Flex Fatigue
Properly designed NR compounds can resist repeated flexing and crack growth, making them useful in springs, mounts, belts and other cyclic components.
Strain-Induced Crystallization
Extension can align chains and form reinforcing crystallites. This helps explain NR strength but does not create resistance to oil, ozone or high temperature.
Tack & Reinforcement
NR can provide useful green tack and adhesion in reinforced constructions. Textile, metal, adhesive, compound and vulcanization must be validated as one system.
Raw-Rubber Grades & Supply Forms
How Do NR Grade and Supply Form Change Performance?
Natural rubber is traded in several forms and grading systems. Technically specified rubber, visually graded sheet or crepe rubber, constant-viscosity grades, latex concentrate and supplier-specific specialty grades differ in how they are produced, inspected and processed.
The raw grade is only one input. Mastication, fillers, plasticizers, antioxidants, antiozonants, cure ingredients and production conditions shape the finished compound, so a critical part should be specified by measurable cured-rubber and application requirements rather than a grade name alone.
| NR Form / Grade | General Direction | Why It Matters |
|---|---|---|
| Technically specified rubber (TSR) | Graded using agreed raw-rubber property criteria rather than appearance alone | ISO 2000 provides procurement guidance; the exact national or supplier grade and certificate fields must be stated. |
| Ribbed smoked sheet (RSS) | Traditional sheet rubber commonly assigned by visual grading rules | Visual grade does not replace compound testing, and RSS should not be treated as interchangeable with a TSR grade. |
| Pale crepe / light-color grade | Selected when raw-rubber color and cleanliness are important | Useful for light-colored compounds, but final color, staining, purity and performance still require a finished-compound specification. |
| Constant-viscosity NR grade | Stabilized to reduce raw-rubber viscosity variation during storage and processing | Can support processing consistency; the grade designation, viscosity target and supplier method must be confirmed. |
| Low-viscosity / processing grade | Designed or prepared for easier mixing, flow or incorporation | Processing convenience must be balanced against green strength, compound properties and the selected manufacturing route. |
| Natural rubber latex concentrate | A preserved aqueous dispersion used for dipping, foam, adhesive and selected molded-latex processes | Latex preservation, solids, stability, protein, cleanliness and process controls differ from dry-rubber compounding. |
| Deproteinized / reduced-protein NR | Processed to reduce specified protein-related content | A reduced test result is not the same as allergen-free; method, sampling, limit and intended use must be agreed. |
| Supplier-specific specialty or masterbatch | May target viscosity, color, traceability, reinforcement or processing consistency | Trade names are not universal specifications; define the raw grade plus cured-compound and finished-part requirements. |
Engineering note: ISO 1658:2022 addresses evaluation of raw NR, while ISO 2000:2020 guides procurement specifications for TSR. Neither standard defines the finished custom part by itself.
Vulcanization
How Do Sulfur Cure Systems Change NR Performance?
NR is commonly vulcanized with sulfur-based systems. Conventional vulcanization (CV), semi-efficient (semi-EV) and efficient vulcanization (EV) use different sulfur-to-accelerator balances and therefore different crosslink distributions. Peroxide and other specialized systems are also possible, but they must be justified by the grade, process, property target and regulatory constraints.
| Selection Factor | Conventional Sulfur (CV) | Semi-EV / EV Sulfur System |
|---|---|---|
| Typical use | Common starting point when dynamic strength, flexing and general NR performance are priorities. | Evaluated when heat aging, reversion control or compression-set retention needs a different crosslink balance. |
| Crosslink direction | Generally favors a higher proportion of polysulfidic crosslinks when correctly formulated. | Generally shifts toward shorter sulfur crosslinks as the system becomes more efficient. |
| Mechanical / dynamic balance | Can support strong tensile, tear and fatigue behavior, but results remain formulation- and test-specific. | Can improve selected aged properties, although dynamic, tear or fatigue trade-offs must be checked. |
| Heat aging / compression set | May be more vulnerable to heat-related crosslink change or reversion in demanding service. | Often considered for improved heat-aging or set balance; actual compound data remain mandatory. |
| Reversion risk | Cure time and temperature need control because prolonged heating can reduce the intended network properties. | System design can reduce reversion risk, but does not remove all heat, aging or processing limits. |
| Production | Scorch safety, cure speed, mold release, bonding and storage depend on the complete formulation. | Mixing sequence, cure window, accelerator restrictions and process controls must follow the approved compound. |
Durometer Selection
What NR Hardness Should You Choose?
NR can be compounded across multiple hardness levels for soft diaphragms, vibration parts, molded springs, wheels, rollers, wear components and reinforced products. Commercial availability does not establish the correct hardness for a particular custom component.
Hardness affects conformity, deformation, load support, contact pressure, rolling behavior, damping and assembly. It does not by itself define rebound, tear strength, abrasion life, heat aging, oil resistance, compression set or service life.
Lower Hardness
Can improve conformity, elastic deflection and cushioning. Geometry and load must still prevent over-deformation, buckling, bottoming or instability.
Medium Hardness
Often provides a practical balance for mounts, diaphragms, couplings, bumpers, wheels and general dynamic molded parts.
Higher Hardness
Can improve load support, cut resistance and dimensional stability, but may increase contact stress, rolling resistance or assembly force and change fatigue behavior.
Specify the hardness method, nominal value and tolerance on the approved material specification. ISO 48-4 or ASTM D2240 can be used for Shore durometer testing when the specimen and method are appropriate.
Thermal & Cold-Service Limits
What Temperature Range Can Natural Rubber Handle?
There is no single NR temperature range that applies to every compound. Raw grade, plasticizer and protective system, cure network, fluid exposure, strain, dynamic heat generation and required life all influence the usable window.
NR can retain useful flexibility at low temperature, but short-term brittleness, long cold storage, crystallization, rebound and functional recovery answer different engineering questions. At elevated temperature, oxidation, reversion, property loss, compression set and dynamic heat build-up must be evaluated together.
Low Temperature
Define whether the part must only survive storage or must flex, rebound, seal or carry load after a stated cold soak. Use a functional test when service performance matters.
Continuous Heat
Long exposure can change hardness, elongation, rebound, sealing force and bond durability. Use aged-property data at the required time and temperature rather than a generic maximum.
Cold Storage & Crystallization
Prolonged cold exposure can create time-dependent stiffening that a brief low-temperature test may miss. State soak duration, recovery time and required function.
Dynamic Heat Build-Up
Cyclic deformation can generate internal heat. Compound hysteresis, frequency, strain, load, geometry and heat dissipation must be reviewed together.
Media Compatibility
What Fluids and Environments Is NR Compatible With?
NR performs well in many dry mechanical duties and selected water or polar-fluid environments, but it is generally not chosen for petroleum oils, fuels or hydrocarbon solvents. Additives, concentration, temperature, pressure, exposure time and compound formulation can all change swelling and property retention.
| Medium / Environment | General NR Direction | Engineering Note |
|---|---|---|
| Dry indoor mechanical service | Generally strong | A common NR starting point when resilience, wear, impact or fatigue dominates and no aggressive fluid is present. |
| Water / dilute aqueous service | Often suitable | Review temperature, pressure, additives, immersion duration, microbial conditions and cleanliness requirements. |
| Alcohols / glycols | Compound-specific | Polar-fluid compatibility can be useful, but concentration, water content, additives and temperature must be tested. |
| Dilute acids / alkaline solutions | Application-specific | Concentration, temperature, exposure time and compound ingredients can materially change suitability. |
| Ozone / outdoor weather | Usually limited | Antiozonants, waxes or barriers can improve resistance, but dynamic strain and long outdoor life still require validation. |
| Mineral oils / greases | Generally poor | Swelling and softening are common risks; NBR or another oil-resistant elastomer is often a better starting point. |
| Petroleum hydraulic fluids / fuels | Usually unsuitable | Do not select NR from mechanical strength alone; identify the exact fluid and compare oil-resistant elastomers. |
| Aliphatic hydrocarbon solvents | Usually unsuitable | Chemical similarity can produce substantial swelling and extraction; laboratory testing is required. |
| Aromatic / chlorinated solvents | Often unsuitable | Swelling or degradation risk can be severe; screen the exact solvent and a more resistant material family. |
| Steam / high-temperature water | Usually not first choice | Heat, oxidation and long-term property loss can limit service; EPDM may be a stronger starting point. |
| Concentrated acids / oxidizing chemicals | Requires review | Do not generalize from dilute-chemical exposure; chemistry, concentration and temperature dominate the risk. |
Material Selection
NR vs. IR, SBR, BR, EPDM and NBR: Which Should You Use?
NR is often selected for resilience, strength, tear, abrasion and dynamic fatigue. Synthetic cis-polyisoprene (IR) can offer more consistent purity or processing but does not duplicate every NR behavior. SBR is often used for economical wear compounds, BR for rebound and low heat build-up in blends, EPDM for weather and hot-water service, and NBR for petroleum oils. Exact compound and duty remain decisive.
| Selection Factor | NR | IR | SBR / BR | EPDM / NBR |
|---|---|---|---|---|
| Resilience / rebound | Strong starting point | Often similar direction; grade-specific | BR is often strong; SBR generally lower | EPDM and NBR are compound-specific |
| Tear / tensile behavior | Distinctive strength potential | Useful but not identical to NR | SBR and BR depend strongly on blend and reinforcement | Usually selected for other environmental strengths |
| Abrasion / fatigue | Strong for many dynamic parts | Useful; validate cut growth and fatigue | SBR supports wear; BR supports rebound and fatigue in blends | Application- and compound-specific |
| Outdoor ozone / weather | Usually limited without protection | Usually limited without protection | Generally limited without protection | EPDM is strong; NBR is usually limited |
| Petroleum oils / fuels | Generally poor | Generally poor | Generally poor | NBR is strong for many oils; EPDM is generally poor |
| Heat-aging direction | Limited relative to heat-resistant families | Similar general limitation | Compound- and blend-specific | EPDM is stronger in suitable non-oil media; NBR is moderate |
| Selection position | High dynamic strength from a natural feedstock | Synthetic polyisoprene consistency option | Economical blend tools for wear, rebound and processing | Environmental or fluid-driven alternatives |
This comparison is directional. Final selection requires the exact compound, load, deformation, speed, temperature, medium, environment, expected life and applicable specification.
Industrial Applications
Where Is Natural Rubber Used?
NR is used where elastic recovery, repeated deformation, impact, wear, tear resistance or reinforcement adhesion dominates the duty. The product type alone does not prove suitability; compound, construction, load, speed, temperature, environment and expected life must be reviewed together.
Wheels, Rollers & Wear Parts
Industrial wheels, caster treads, rollers, scrapers and abrasion parts where load, speed, slip, surface, heat build-up and wear mode are defined.
Springs, Bumpers & Couplings
Molded springs, impact stops, couplings and elastic drive components using NR resilience, strength and repeated-deformation performance.
Vibration Isolation & Bearings
Mounts, bridge or machinery bearings, bushings and bonded isolators where stiffness, damping, fatigue and bond durability are engineered together.
Belts, Hoses & Reinforced Parts
Conveyor and transmission components, selected hoses and fabric-reinforced products where adhesion, flex life and dynamic heat generation are controlled.
Diaphragms, Bladders & Flexible Parts
Flexible diaphragms, bladders, sleeves and protective components in compatible media and controlled indoor or protected environments.
Latex-Dipped, Foam & Adhesive Products
Gloves, balloons, elastic threads, foam, adhesives and other latex-process products requiring separate latex stability, protein and cleanliness controls.
Compression Set & Failure Analysis
Why Do NR Parts Crack, Swell, Wear or Lose Performance?
NR failures are usually traced to a mismatch among compound, load, deformation, speed, temperature, ozone, fluid, geometry, reinforcement, bonding and processing. Swelling, ozone cracking, heat aging, abrasive loss, tear growth, fatigue cracking and bond loss point to different mechanisms and should be diagnosed separately.
Compression set matters in static supports, diaphragms and mounts because a part can lose recovery or contact force even when it remains dimensionally recognizable. The result depends on formulation, cure state, time, temperature, compression level, dynamic history and recovery procedure.
| Observed Symptom | Possible Causes | What to Review |
|---|---|---|
| Oil or fuel swelling / softening | Incompatible petroleum fluid, additives, excessive temperature or wrong material family | Exact medium, immersion data, volume change, aged properties and oil-resistant alternatives. |
| Hardening / loss of elongation | Heat and oxygen aging, ozone, insufficient protection or excessive thermal history | Temperature history, aged hardness and tensile data, antidegradant system and environment. |
| Surface ozone cracks | Tensile strain, ozone exposure, inadequate wax or antiozonant protection, outdoor duty | Crack orientation, strain state, ozone test, surface protection and a weather-resistant alternative. |
| Rapid wear / chunking | Wrong abrasion mode, excessive slip, sharp debris, overload, heat build-up or weak compound | Contact surface, speed, load, slip, temperature, abrasion and tear test relevance. |
| Tear / flex-crack growth | High cyclic strain, sharp radii, cuts, poor reinforcement, heat or cure imbalance | Geometry, motion, frequency, temperature, initial damage, cure system and fatigue method. |
| Permanent deformation | Compression set, creep, heat, over-compression, under-cure or aging | Load and compression history, cure state, test conditions and retained force or height. |
| Bond / reinforcement failure | Surface preparation, adhesive mismatch, contamination, corrosion or insufficient cure | Substrate, textile treatment, adhesive, compound, cure process and bond acceptance test. |
Manufacturing
How Are Custom Natural Rubber Parts Manufactured?
NR can be processed into molded parts, extruded and calendared products, wheels and rollers, fabric-reinforced components, rubber-to-metal bonded parts and latex-dipped or foamed articles. The route depends on supply form, geometry, compound, tolerance, quantity, tooling and validation requirements.
- Application review:Confirm load, deformation, speed, motion, temperature, medium, environment and expected life.
- Compound definition:Select NR supply form, grade direction, hardness, reinforcement, cure approach and required dynamic or aging properties.
- Tooling / process review:Choose compression, transfer, injection, extrusion, calendering, dipping, foaming, bonding or a combined process.
- Sample validation:Check dimensions, appearance, fit and agreed mechanical, aging, media, bond, fatigue or functional tests before approval.
- Production control:Control raw grade, compound batch, cure process, cavities, dimensions, appearance, bonding and traceability to the agreed plan.
Molded NR
Suitable for wheels, rollers, springs, bumpers, couplings, diaphragms, mounts and complex 3D parts. Tooling and process depend on geometry and volume.
Extruded & Calendared NR
Used for profiles, sheets, friction layers and selected hose or belt constructions. Cross-section, gauge, grain direction, joining and surface requirements must be specified.
Fabric-Reinforced NR
Textile reinforcement can support belts, hoses, diaphragms and flexible components where controlled deformation, adhesion and fatigue life are required.
Rubber-to-Metal NR
Bonded NR parts combine rubber with metal inserts or carriers. Surface preparation, adhesive, metal grade, corrosion protection and bond testing need definition.
Latex & Foam Processing
Preserved latex can be compounded for dipping, casting, foam and adhesive processes that require controls different from dry-rubber mixing and molding.
Secondary Operations
Trimming, grinding, cutting, joining, surface finishing, marking, cleaning, inspection and packaging should be defined whenever they affect performance.
Dimensions & Design
What Tolerances Can Be Achieved on NR Parts?
There is no universal tolerance for “natural rubber.” Achievable tolerances depend on part size, geometry, mold-dependent versus mold-independent dimensions, compound shrinkage, tool construction, flash location, process, reinforcement and measurement method.
ISO 3302-1:2014 is a common dimensional-tolerance reference for molded, extruded and calendared solid rubber products. It does not replace product-specific standards, approved drawings or separately agreed requirements for latex-dipped articles, cellular rubber, coated fabrics, wheels and bonded assemblies.
Define Critical Characteristics
Identify tread diameter, wall thickness, loaded height, spring interfaces, bond areas, concentricity, hole positions and other dimensions that control function.
Avoid Unnecessary Tight Tolerances
Tighter tolerances increase tooling, measurement and process-control demands. Apply precision only where it protects fit, load, balance, motion or assembly.
Agree Flash & Surface Criteria
Parting line, flash, gate, trimming, grind, flow marks, reinforcement exposure and cosmetic limits should be defined separately from dimensional tolerance.
Confirm Measurement Method
Soft rubber deforms under measurement force. Define conditioning, datums, fixtures, runout method and test force for compression-sensitive dimensions.
Validation & Quality
Which Tests Should Be Specified for Natural Rubber?
A useful NR test plan starts with the dominant failure risk. Hardness and tensile data alone cannot establish abrasion life, rebound, tear propagation, heat build-up, flex fatigue, ozone resistance, bond durability or behavior in the finished assembly.
| Property / Risk | Common Test Reference | What to Define |
|---|---|---|
| Raw-rubber grade / evaluation | ISO 1658 / ISO 2000 and agreed supplier specification | Supply form, grade, origin or traceability need, test certificate fields and lot acceptance. |
| Hardness / tensile properties | ISO 48-4 / ISO 37 | Scale, nominal value, tolerance, specimen type, conditioning and original or aged limits. |
| Tear strength | ISO 34-1 | Test-piece type, nick condition, direction, speed, temperature and minimum result. |
| Abrasion resistance | ISO 4649 | Method, reference abrasive, density, result format and relevance to the actual wear mechanism. |
| Rebound / dynamic behavior | ISO 4662 / agreed dynamic test | Temperature, specimen, rebound target, load, frequency, heat build-up and acceptance criteria. |
| Flex cracking / fatigue | ISO 132 / ISO 6943 or product-specific cycling | Strain, cut or no-cut condition, cycle rate, temperature, crack or life criterion. |
| Heat / ozone aging | ISO 188 / ISO 1431-1 | Temperature, duration, strain, ozone concentration and permitted property or cracking change. |
| Compression set / liquid resistance | ISO 815-1 / ISO 1817 | Compression and recovery or exact fluid, temperature, duration and permitted change. |
| Dimensions / application validation | Approved drawing and customer-specific test | Critical dimensions, load, speed, deformation, wear, bond, balance, fatigue and assembly conditions. |
Relevant current references include ISO 1629:2025, ISO 1658:2022, ISO 2000:2020, ISO 37:2024, ISO 34-1:2022, ISO 4649:2024, ISO 4662:2017, ISO 132:2017, ISO 188:2023, ISO 1817:2024, ISO 1431-1:2024 and ISO 815-1:2019. These standards provide nomenclature, evaluation guidance or test methods, not a universal finished-part certification.
Regulatory & Documentation
Does NR Automatically Meet FDA, Medical or Sustainability Requirements?
No. NR identifies a material family, not a compliance status. Natural origin does not automatically establish food-contact, drinking-water, medical, biocompatibility, low-protein, allergen, PAH, RoHS, REACH, sustainability, chain-of-custody or biodegradation claims.
Dry natural rubber and natural rubber latex also require different risk review. For human-contact or medical uses, state whether latex or dry NR is present and identify the applicable labeling, extractable-protein, biological, cleanliness and product requirements. A reduced protein result must not be presented as proof that all natural-rubber allergens are absent.
Purchasing Guide
What Information Should You Send for an NR RFQ?
A quote can look complete but still carry material risk if it contains only “natural rubber, black, 60 Shore A.” For NR, load, deformation, motion, wear mode, dynamic temperature, ozone exposure and material supply form can be as important as hardness and geometry.
| RFQ Item | Information to Provide | Why It Matters |
|---|---|---|
| Geometry | 2D drawing, 3D model or physical sample; identify revision | Defines tooling, parting, dimensional risk and inspection. |
| Function | Wheel, roller, spring, mount, coupling, diaphragm, reinforced part, dipped latex article, etc. | Changes the important rebound, wear, fatigue, bonding and validation requirements. |
| Material form | Dry NR, TSR or RSS grade, constant-viscosity grade, latex concentrate or supplier specification | Prevents unlike raw-rubber forms and grading systems from being treated as interchangeable. |
| Temperature | Minimum, cold-soak duration, continuous maximum, peak maximum and peak duration | Controls cold recovery, crystallization, heat aging, reversion and compression-set risk. |
| Medium | Exact water, chemical, oil, grease, fuel or cleaning agent; include grade, concentration and additives | Determines swelling, extraction and whether NR is an appropriate starting material. |
| Pressure / load | Normal and maximum load, contact pressure, compression, impact or shock condition | Affects hardness, reinforcement, deformation, heat generation and geometry. |
| Motion | Static, rotating, rolling, reciprocating, flexing, vibrating or repeated compression | Changes fatigue, friction, abrasion, heat build-up and bond requirements. |
| Weather / ozone duty | Indoor or outdoor location, UV, ozone, strain state and protection method | Prevents NR mechanical strengths from being mistaken for long-term weather resistance. |
| Material target | NR grade or customer specification if fixed; hardness, color, density, reinforcement and cure restrictions | Separates mandatory requirements from supplier recommendations. |
| Tolerances | Critical dimensions, tolerance standard and inspection method | Controls tooling, process capability and measurement cost. |
| Compliance | Exact food, medical, protein, chemical, sourcing, traceability or customer documentation required | Prevents “natural” from being mistaken for a regulated or certified claim. |
| Testing | Raw grade, tensile, tear, rebound, abrasion, fatigue, aging, media, bond or functional validation | Allows validation scope, cost and timing to be reviewed before production. |
| Quantity / logistics | Prototype and order quantity, annual demand, packaging, lot and traceability requirements | Influences tooling, manufacturing route, raw-material control and delivery format. |
NR FAQ
Frequently Asked Questions About Natural Rubber
These answers are material-family guidance. Final performance must be confirmed against the exact NR grade, compound, finished-part construction and service conditions.
What is natural rubber made from?
Commercial NR is based mainly on cis-1,4-polyisoprene obtained from plant latex, most commonly Hevea brasiliensis. Raw rubber also contains non-rubber constituents, and the finished compound adds fillers, cure ingredients and protective additives.
Is natural rubber the same as natural rubber latex?
No. Natural rubber latex is an aqueous dispersion used in dipping, foam and other latex processes. Dry natural rubber is coagulated and processed into solid raw rubber for mixing, extrusion, calendering and molding. Their controls and product risks differ.
What is the difference between NR and synthetic polyisoprene (IR)?
Both are predominantly cis-1,4-polyisoprene, but IR is synthetically produced and can offer more consistent purity or processing. Natural non-rubber constituents and structural differences mean IR does not automatically reproduce every NR property.
Why does natural rubber have high strength and resilience?
NR chain structure and strain-induced crystallization support high elastic recovery, tensile and tear performance. The realized result still depends on grade, reinforcement, cure system, geometry, temperature and strain rate.
Is natural rubber oil resistant?
NR is generally not a first choice for petroleum oils, fuels or hydrocarbon solvents because swelling and softening can occur. Identify the exact fluid and compare NBR, HNBR, FKM or another compatible elastomer.
Is natural rubber suitable for outdoor use?
Unprotected NR is vulnerable to ozone, sunlight and oxidative weathering. Antiozonants, waxes, coatings or barriers can improve durability, but dynamic outdoor parts still require testing or a weather-resistant alternative such as EPDM.
What temperature can natural rubber withstand?
There is no universal NR service range. Compound, cure network, load, motion, fluid, cold-soak time, dynamic heat generation and required life determine the usable minimum and maximum temperatures.
What Shore hardness is natural rubber?
NR is not one fixed hardness. The correct durometer depends on load, deflection, contact pressure, rebound, vibration, rolling behavior, assembly and required recovery.
What is the difference between CV, semi-EV and EV curing in NR?
These sulfur systems use different sulfur-to-accelerator balances and create different crosslink distributions. CV can favor dynamic strength, while semi-EV or EV may improve selected heat-aging or set properties; the exact trade-off must be tested.
Is natural rubber suitable for wheels and rollers?
NR can be an excellent candidate for wheels and rollers requiring rebound, tear and wear performance. Load, speed, slip, surface, abrasive type, heat build-up, bond design and ozone exposure still determine service life.
NR or SBR: which should I choose?
NR is often favored for resilience, tear strength and dynamic fatigue. SBR can be an economical wear-oriented option or blend component. Compare the exact formulation, abrasion mode, temperature and service life.
When should EPDM or NBR replace NR?
EPDM is usually a stronger starting point for ozone, outdoor weather, hot water and many glycol services. NBR is usually stronger for petroleum oils. NR remains attractive when dynamic mechanical performance dominates.
Is natural rubber food grade?
No. A specific NR formulation, regulatory basis, manufacturing control, migration or extractables testing and documentation scope must be confirmed for the intended food-contact conditions.
Can natural rubber cause latex-allergy concerns?
Natural rubber latex contains proteins associated with allergic reactions in susceptible people, and dry NR or human-contact products can have labeling implications. Do not claim “latex-free” or “hypoallergenic” from an unverified material description or single test.
What information is needed to quote a custom NR part?
Send the drawing, 3D model or sample together with load, deformation, speed, motion, temperature, medium, environment, hardness, grade or supply form, tolerances, compliance, testing and quantity requirements.
Custom NR Components
Have an NR wheel, roller, spring, mount, diaphragm or reinforced part to develop?
Send the available drawing or sample information together with load, deformation, speed, motion, temperature, medium, environment, hardness or grade target and expected quantity. We can review the NR material direction, manufacturing feasibility and technical information still needed before quotation.
