Neoprene (CR) for Custom Molded Components — Properties, Applications & Specifications
Table of Contents
Neoprene (CR) is built around a chlorine-substituted polymer backbone that disrupts the electron transfer pathways responsible for ozone and UV degradation — the chlorine atoms electronically stabilize the double bonds that ozone attacks in hydrocarbon rubbers, making CR inherently resistant to surface cracking without requiring chemical additives. This prevents the classic ozone-induced surface crazing failure mode that eliminates materials like natural rubber and SBR from outdoor static sealing applications within 1–3 years of UV exposure. Fenlora molds CR compounds in 40–70 Shore A hardness ranges as weatherstrip seals, vibration isolation mounts, and electrical cable grommets for HVAC equipment manufacturers and marine OEMs across North America.
Material Properties & Specifications
| Common names / abbreviations | Neoprene (CR) |
|---|---|
| Polymer structure / monomer system | Polychloroprene |
| Tg (°C) / Brittle Point | -43 °C |
| Density (g/cm³) | 1.23 - 1.25 |
| Hardness range (Shore A/D) | 15 - 95 Shore A |
| Tensile strength (MPa) | 3.4 - 24.1 |
| Elongation at break (%) | 100 - 800 |
| 100% / 300% modulus (MPa) | 0.68 - 20.6 at 100% |
| Rebound / tanδ (temp + freq) | 50 - 80 % Rebound |
| Compression set (%) | 20 - 60 % |
| Continuous service temp (°C) | -34°C to 100°C |
| Environmental & Fluid Resistance | Ozone: Excellent | Oil: Moderate |
| ASTM D2000 Callouts | ASTM D2000 M1BC 303 |
| Electrical properties | Vol Res: 2.0 x 10^13 ohm-cm |
| Thermal properties | Thermal Cond: 0.11 - 0.19 W/mK |
| Tear Resistance | Tier 4 - Strong |
| Abrasion Resistance | Tier 4 - Strong |
| Gas Impermeability Resistance | Tier 5 - Excellent |
| Oxygen Resistance | Tier 4 - Strong |
| Ozone Resistance | Tier 4 - Strong |
| Weathering Resistance | Tier 4 - Strong |
| Oil Resistance | Tier 3 - Balanced |
| Acid Resistance | Tier 4 - Strong |
| Alkaline Resistance | Tier 5 - Excellent |
| Water Resistance | Tier 4 - Strong |
| Flame Resistance | Tier 4 - Strong |
| Chemical Resistance | Tier 5 - Excellent |
When to Specify CR
Neoprene CR sits at a practical midpoint in the elastomer spectrum — it won’t outperform Viton in chemical resistance or EPDM in heat, but it handles combinations of stressors that eliminate single-property materials.
| Use Neoprene CR when… | Avoid Neoprene CR when… |
|---|---|
| Static or dynamic seals face continuous outdoor UV and ozone exposure without housing protection | Contact with petroleum-based oils or fuels is continuous (swell rates exceed acceptable limits) |
| Operating temperatures range from –40°C to +120°C with occasional excursions to +130°C | Application requires resistance to concentrated ketones, esters, or chlorinated solvents |
| Part must resist moderate oil mist or splash (not immersion) in refrigeration or HVAC systems | Continuous immersion in aromatic hydrocarbons is required |
| Vibration isolation mounts need weatherability combined with dynamic fatigue resistance | FDA food-contact or USP Class VI biocompatibility is required |
| Flame-spread resistance is a secondary requirement in wiring harness or electrical enclosure applications | Service temperatures exceed 130°C continuously |
Neoprene’s ozone resistance deserves more technical attention than it typically gets in datasheets: standard hydrocarbon rubbers (NR, SBR) fail by ozone attack at strained surfaces because ozone preferentially cleaves carbon-carbon double bonds under mechanical stress — a concentration as low as 0.02 ppm at 20% elongation will initiate cracking in NR within 24 hours. CR’s chlorinated backbone raises the activation energy for this reaction significantly, which is why outdoor weatherstrip applications on building facades, marine hatch seals, and rooftop HVAC equipment default to CR as the minimum-spec elastomer even when cost is a constraint.
Custom Parts We Make in CR
Fenlora manufactures the following CR components to print or from functional specifications, with compound hardness and cure system selected for the specific thermal and chemical environment.
→ Weatherstrip and door perimeter seals — CR’s combined UV, ozone, and moisture resistance makes it the standard compound for exterior sealing profiles on HVAC enclosures, electrical cabinets, and marine hatches where NR or SBR would check-crack within two seasons.
→ Vibration isolation mounts and anti-vibration pads — CR maintains consistent dynamic modulus across the –40°C to +100°C range relevant to rooftop mechanical equipment, preventing the stiffness creep that causes isolation systems to fall out of tuned frequency at temperature extremes.
→ Electrical cable grommets and strain relief bushings — CR’s inherent flame retardance (it self-extinguishes due to HCl release during combustion) makes it a practical choice for wire pass-through grommets in panel boards and junction boxes where halogenated materials are not prohibited. (See rubber grommets product page)
→ Refrigerant-side diaphragm seals — CR shows acceptable swell characteristics in R-22, R-134a, and R-410A refrigerant atmospheres and has a long track record in HVAC compressor and valve assemblies; not suitable for HFO-1234yf without compound-specific testing.
If your drawing specifies Neoprene CR or you’re working from functional requirements, contact our engineering team to discuss compound selection and hardness range. [contact us]
Industries That Use CR
Electrical
Enclosure weatherstrip seals, cable entry grommets, and gland seals in CR provide UV/ozone durability for outdoor electrical cabinets, switchgear, and utility metering enclosures where flame spread characteristics also matter. (See electrical/electronics page)
Body weatherstrip, underhood wire harness grommets, and door seal bulbs in CR remain common in OEM and aftermarket applications where cost, weatherability, and moderate oil splash tolerance must be balanced against each other. While EPDM has displaced CR in some door weatherstrip applications, CR remains preferred where moderate oil proximity is a factor. (Link to automotive rubber parts)
HVAC and Industrial Machinery
CR is specified for compressor vibration mounts, refrigerant line grommets, and weatherstrip gaskets on air handling units — applications where the equipment sits outdoors for 15–20 year service lives in direct UV exposure. The combination of moderate refrigerant resistance and reliable low-temperature flexibility down to –40°C makes CR the default compound for rooftop equipment sealing in North American climate zones.
Compare Materials
Neoprene CR handles the overlap between weatherability and moderate chemical exposure well, but specific conditions push toward more specialized compounds.
| If your application involves… | Consider instead |
|---|---|
| Oil, fuel, or hydraulic fluid exposure | Nitrile (NBR) |
| Extreme chemical or solvent resistance | Viton (FKM) |
| Continuous temps above 150°C | Silicone (VMQ) |
| High dynamic flex and tear resistance | Natural Rubber (NR) |
| High abrasion and mechanical wear | Polyurethane (AU/EU) |
| Outdoor UV or ozone weathering only, no oil | EPDM |
| Air/gas impermeability | Butyl (IIR) |
| Cost-sensitive general-purpose use | SBR |
Not sure which material fits your application? Send us your requirements and we’ll recommend the right compound.