Comparison of Physical Properties between Superlon’s...

SUPERLON WORLDWIDE SDN. BHD. (252355-U)

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Tel: +60 3 5161 7778 | Fax: +60 3 5162 7778

Email: [email protected] | Website: www.superlon.com.my

Comparison of Physical Properties between Superlon’s NBR and EPDM

Overview

Recently, there have been discussions of the differences between NBR and EPDM elastomeric

insulation materials. This article is intended to compare the physical properties between the

two polymers, NBR and EPDM rubber. The performances will be based on true specifications

from manufacturer’s catalogs, along with our own in house testing to see if the figures are in

fact true.

Physically and visually, NBR and EPDM rubber insulation look exactly the same. Both materials

are black in colour, closed cell foamed elastomers. Below are the specifications of Superlon NBR

rubber compared to and EPDM based insulation manufacturer.

*¹ Figure is tested in house by Superlon

*² Superlon rounds its figures to the three decimal places

*³ μ factor is calculated based on water vapour permeability figures

Superlon EPDM

1 Material Nitrile Butadiene Rubber Foam Elastomer

Ethylene Propylene Diene Monomer Foam Elastomer

2 Cell Structure Closed Cell Closed Cell

3 Density 40kg/m³ - 70kg/m³ 40kg/m³ - 80kg/m³

4 Service Temperature -50°C to 105°C -57°C to 125°C

5 Tensile Strength 200-280 KPa 110 – 190 KPa *¹

6 Fire Resistance Class 1, Class O, UL94, FM Approved

UL94, ASTM E84, FM Approved

7 Thermal Conductivity*²

W/m.K 0°C - 0.034 0.033

Mean Temp 20°C 0.036 0.0356

40°C ----- 0.038 0.0374

8 Water Vapour Permeability ≤ 2.9 x 10¯¹⁴ kg/Pa.m.s < 1.44 x 10¯¹³ kg/Pa.m.s

Water Absorption by volume

≤ 0.2%

≤ 0.2%

9 Ozone Resistance Corrosion Resistance Environment

Good No Corrosion Dust & Fibre Free, CFC Free

Very good No Corrosion Dust & Fibre Free, CFC Free

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http://www.superlon.com.my/



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Based on the specifications above there are some similarities and differences.

1. Material

Nitrile Butadiene Rubber (NBR) and Ethylene Propylene Diene Monomer (EPDM) have several

differences. In the rubber insulation industry, NBR is the most widely used across the world. NBR

insulation has been a proven material long before the introduction of EPDM insulation.

NBR widely used as it has good resistance to oils, water and solvents and is very beneficial for

installers working at a construction site. An even more important aspect of NBR is its excellent

compression set (less chance of deformation), very good tear resistance and abrasion resistance.

EPDM insulation is rarely used in the insulation market except for a select few manufacturers. The

main benefits to EPDM are its weather aging and ozone resistance. It also has very good resistance

to polar fluids and better heat resistance compared to NBR. EPDM generally has poorer compression

set, poorer tear resistance and abrasion resistance compared to NBR.

These differences will further be discussed below.

2. Cell Structure

Both NBR and EPDM is closed cell and are very similar in structures.

3. Density

NBR and EPDM insulation have very similar densities ranging from 40kg/m³ - 80kg/m³.

4. Service Temperature

One of the differences between NBR and EPDM is the service temperature. In this instance EPDM

has a higher temperature resistance compared to NBR with EPDM able to resist temperatures up to

125°C compared to NBR’s resistance of up to 105°C. At higher temperatures of greater than 100°C,

EPDM insulation will degrade less than NBR and is therefore more suitable for higher temperature

applications such as low pressure steam.

However in light of the slightly higher temperature resistance EPDM has over NBR, rubber insulation

is mostly targeted for its low temperature applications. Due to rubber insulation’s excellent thermal

conductivity and low water vapour permeability, NBR and EPDM insulation will benefit most in low

temperature applications so that it can prevent condensation for air conditioning systems, chillers

and other cold/freezing applications.





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EPDM often tries to market itself as a better high temperature alternative compared to NBR,

however for high temperature applications EPDM is severely limited by its service temperature of

125°C. Other better insulating alternatives are fiberglass which has temperature resistance of up to

350°C or even mineral wool which has a service temperature of more than 1000°C depending on its

density.

5. Tensile Strength, Tear Strength and Abrasion Resistance

The major most importance difference between NBR and EPDM is the strength of Superlon’s NBR

insulation. Superlon’s NBR has better tensile strength, tear strength and abrasion resistance. It is the

strength of Superlon’s materials that separates Superlon’s insulation against EPDM. EPDM insulation

is stiffer with less elasticity compared to NBR.

Tested in house, Superlon’s NBR performs much better than EPDM insulation. Superlon NBR has a

tensile strength of 200-280kPa whereas EPDM has a tensile strength of only 100-190kPa.

NBR has an inherent added resistance against tear and abrasion resistance against EPDM, however

with Superlon’s specially formulated materials; Superlon is the leading insulation in the market with

the best tensile strength tear strength and abrasion resistance.

The strength of the material is important as it is crucial to installers in the field as Superlon’s

materials are less borne to breakages and tearing compared to EPDM. The better strength

properties also mean that NBR is easier to install and fabricate, which will save time and money for

every project undertaken.

6. Fire Resistance

Nitrile rubber and EPDM both have similar fire and smoke properties. Products are listed in

Underwriters Laboratories (UL), both have Class 1, Class O and Factory Mutual (FM) certifications.

There have been suggestions that putting NBR in a microwave may cause more smoke than EPDM.

While EPDM could have better smoke properties than NBR when tested in a microwave, this does

not provide a realistic purpose of what the insulation is used for. Rubber insulation is mostly used in

buildings for the HVAC industry, it is extremely unlikely that the rubber insulation will be in contact

with a microwave or any microwave emitting materials.

With rubber insulation’s using very similar fire retardant raw materials, fire resistance between NBR

and EPDM are similar, with the two types of rubber sharing the same fire resistance test reports and

similar smoke properties.





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7. Thermal Conductivity

NBR and EPDM insulation share similar thermal conductivities at different temperatures. This means

that both materials have similar insulating effects in the short term. The lower the thermal

conductivity means that a lower thickness can be selected which can save costs. For thermal

conductivity to remain for the course of the installation, water vapour permeability and water

absorption is needed to determine the long term thermal conductivity.

8. Water Vapour Permeability and Water Absorption

Both NBR and EPDM have similar water vapour permeability and water absorption figures. These

figures are the most important in determining the long term thermal conductivity of the product.

Over time, as water permeates and absorbs through the material, the K-Value of the insulation will

increase depending on how much water is absorbed. Therefore, the lower the water vapour

permeability and water absorption, the better long term performance of the insulation.

In comparison, NBR insulation tends to have lower water vapour permeability and lower water

absorption. NBR has a moisture resistance factor of 7,000 to 10,000 or more whereas EPDM

insulation only has a moisture resistance factor of up to 7,000. This means that without the use of

vapour barriers, Superlon's NBR insulation can have a longer lasting thermal effect compared to

EPDM.

9. Weather and Environment

When comparing outdoor and environmental resistance, NBR and EPDM perform similarly with both

materials resistant to ultra violet (UV) rays. EPDM in some cases perform slightly better under heavy

UV conditions however exposed to extreme UV and weather conditions, both NBR and EPDM will

need jacketing or use weather paint to protect it from extremities from the outside.

Conclusion

NBR and EPDM both have their benefits in different applications, however when specifically

comparing the materials for the HVAC industry, NBR is a better option because of its better tear

strength, ease of installation, and its resistance to oils and other chemicals which are all very

important when working on the project site.

NBR insulation has been in the market for far longer than EPDM insulation. NBR has been proven to

be the most effective in conserving energy and preventing condensation, and is the widely used

material in rubber based polymeric insulation.



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