UV Resistant Rubber Guide

In this article we focus on one particular attribute of various types of elastomers; their ability to withstand UV light.

Prolonged exposure to direct sunlight can have a detrimental affect on rubber compounds, however some hold up in this environment far better than others. Here we detail some of the factors that come into selecting a rubber for outdoor use and provide an overview of the best types of rubber sheet for these applications.

Factors Affecting an Elastomer's Weather Resistance.

To choose a rubber that will perform well, it is important to understand the factors it will be exposed to. Given that most of you reading this would be looking for a rubber to be used outdoors, it is necessary to consider more than just UV resistance. Other things that will impact the rubber often include heat from sunlight, overall application temperature and ozone.

Sunlight

The heat generated from exposure to direct sunlight will, of course, vary depending on conditions. That said, in some circumstances direct exposure can raise the internal temperature of a rubber component to above 60°C. The nature of the heat source also results in repeated heat cycling which can cause some elastomers to become brittle faster, accelerating their compression set and reducing elasticity.

Temperature

Similar to the above, different application conditions will impact your selection of a rubber material. Most elastomers will handle at least 70°C, past that the list of viable compounds begins to decrease. If your application requires a rubber seal for over 130°C options become very limited with the two main ones being silicone rubber and Viton rubber (both of which have excellent UV resistance).

Ozone

This occurs naturally so all rubbers have some resistance. However, it can also be generated in more concentrated amounts (such as in outdoor enclosures which house electrical equipment). In these situations, choosing a rubber with good ozone resistance will increase the life span of the part.

Rubber Weather and UV Resistance Table.

The table below contains an overview of the most common types of rubber compounds ability to withstand UV light, weathering and to hold up outdoors.

We've rated these from Poor to Excellent.

Please note that this information is general in nature and does to every grade of rubber equally. Different grades of silicone will behave differently outdoors. Similarly, composite materials often take on the characteristics of their weakest ingredient depending on their construction.

Rubber Type	Weather Resistance	Abbreviation
Butyl Rubber	Excellent	IIR
EPDM Rubber	Excellent	EPDM, EPM
Natural Rubber	Poor / Fair	NR, IR
Neoprene Rubber	Good	CR
Nitrile Rubber	Fair	NBR
Silicone Rubber	Excellent	SI
Styrene Butadiene Rubber	Poor / Fair	SBR
Viton Rubber	Excellent	FKM

It's quite clear that the best options for prolonged outdoor exposure include Butyl, EPDM, Silicone and Viton (Neoprene is also viable in a lot of applications and is more economical). Below we cover a few of each types main features and include links where you can find more information of shop our large range of rubber sizes.

EPDM Rubber.

EPDM has excellent weather resistance and is available in a large range of sizes. Quality grades of EPDM Rubber Sheet withstands attack from ozone, oxygen and a range of chemicals and dilute acids and alkalis. This type or rubber can tolerate moderate heat up to 120°C. It also handles low temperatures ok (down to -30°C).

One issue with EPDM is that is slightly harder to bond than most rubber compounds (silicone is worse again). We do have glues for the job though (including our GMK 2510) so don't hesitate to contact us if you need an adhesive for gluing EPDM rubber.

Our industrial grade EPDM is available in a number of different forms online. It is sold by the metre (1200mm wide) and in a huge range of cut strip sizes. A potable water grade is also available.

For custom EPDM gaskets, strips or parts, please don't hesitate to contact us.