In sensitive applications—automotive interiors, medical devices, aerospace cabins, electronics enclosures, and vacuum systems—rubber off-gassing and VOC emissions can be just as important as tensile strength or compression set.

While all elastomers can release small amounts of volatile compounds, emission behavior varies significantly by rubber type and formulation. Choosing the wrong material can lead to odor complaints, fogging on optical surfaces, sensor interference, or failure to meet regulatory standards.

This guide from Primo Rubber Co. focuses specifically on how different rubber families compare when it comes to VOC release and long-term off-gassing.

What Causes Rubber to Off-Gas?

Rubber off-gassing is influenced by several factors, including the polymer chemistry, the type of cure system used (sulfur versus peroxide), the oil content, the post-cure process, and the service temperature. These variables determine the level and rate of volatile emissions from the material.

VOC Comparison by Rubber Type

Silicone (VMQ / LSR)

General emission profile: Low (when properly post-cured)

Silicone rubber is often chosen for low-VOC applications because it contains no plasticizers, has inherently stable polymer chains, performs well at high temperatures, and can be post-cured to remove residual volatiles. However, without proper post-curing, silicone can release residual siloxanes and cure byproducts

EPDM (Ethylene Propylene Diene Monomer)

General emission profile: Low to Moderate (formulation dependent)

EPDM is widely used in automotive interiors and outdoor seals because it offers good chemical stability, does not require heavy plasticization, and provides strong resistance to ozone and UV exposure. However, its VOC performance depends heavily on factors such as the level of oil extension, the cure chemistry used, and the specific additive package included in the formulation. Low-VOC EPDM compounds are commonly available for interior automotive use.

NBR (Nitrile Rubber)

General emission profile: Moderate to High

NBR often contains processing oils and plasticizers to improve flexibility and workability, as well as sulfur cure residues that remain from the vulcanization process. Because nitrile is commonly oil-extended, it may produce noticeable odor or volatile emissions—especially in confined spaces. Hydrogenated NBR (HNBR) performs somewhat better but can still emit depending on formulation. Not typically ideal for odor-sensitive interior environments without special formulation.

FKM (Fluoroelastomer)

General emission profile: Very Low (after proper cure)

FKM materials are highly stable and chemically resistant. They are typically more expensive but offer excellent emission control. They have low volatile content, resist high temperatures and perform well in vacuum environments

Butyl Rubber (IIR)

General emission profile: Very Low Permeability, Low to Moderate VOC (formulation dependent)

Butyl rubber is unique because it has extremely low gas permeability, excellent sealing capability, and strong resistance to air diffusion, making it especially well suited for airtight and pressure-retaining applications. This makes it ideal for applications where gas containment is critical. However, butyl can contain processing oils and additives that contribute to VOC emissions if not properly formulated. When compounded for low-VOC performance, butyl rubber can be a strong candidate for sealed-system applications. The advantages of this material include low gas transmission, good chemical resistance, and strong damping properties, making it suitable for applications requiring airtightness, durability, and vibration absorption.

Natural Rubber (NR)

General emission profile: Moderate to High

Natural rubber can produce a noticeable odor, organic volatiles from natural proteins, and oxidative byproducts over time. It also requires stabilizers to prevent degradation, which may contribute to emissions.

Quick Comparison

Rubber Type Relative VOC Level Best Suited For
Silicone (post-cured) Low Medical devices, electronics, optical assemblies, automotive interiors, sealed enclosures
FKM Very Low Aerospace systems, vacuum sealing, high-temperature electronics, chemical processing
EPDM (low-VOC grade) Low–Moderate Automotive weatherstripping, HVAC seals, outdoor enclosures, water-contact systems
Butyl (IIR) Low–Moderate Gas barrier components, pharmaceutical stoppers, vacuum seals, air-retention systems
HNBR Moderate Oil-resistant industrial systems with moderate emission sensitivity
NBR Moderate–High Industrial equipment, oil and fuel systems (non-sensitive environments)
Natural Rubber Moderate–High Mechanical components and abrasion-heavy environments where emissions are not critical

When Should You Worry About Off-Gassing?

You should evaluate emissions if your rubber part will be used in:

  • -Enclosed cabins
  • -Medical environments
  • -Optical or lens assemblies
  • -Sensor housings
  • -Vacuum systems
  • -Battery enclosures
  • -Automotive interiors
  • -Semiconductor equipment

Need a Low-Emission Rubber Compound?

Primo Rubber Co. specializes in injection molding custom rubber components. Contact Primo Rubber Co. today to discuss your project and find the ideal material, design, and tooling solution for your rubber parts.