Tuesday, July 21, 2009

Technical Aspects of EPDM (Liquid Roof and Liquid Rubber)

Elastomeric coatings are roofing applied in a viscous state. It has elastic properties, and can stretch in the summer time heat and then return to their original shape without damage.
Elastomeric coatings usually contain polymeric materials, such as acrylic, and a white pigment, such as titanium dioxide, to make them opaque and reflective. An elastomeric coating is applied thicker than paint. An elastomeric coating can be used on virtually any substrate including asphalt built-up roofing, concrete roofing, metal roofing, modified bitumen roofing, polyurethane foam roofing and single ply roofing.

Liquid Roof and Liquid Rubber need temperatures above 55 degrees to cure. The temps can go below 55 but the product will not begin curing again until the temp's go above 55 degrees.

Chemical Resistance-Cured EPDM rubber is resistant to acids, alkalis and polar solvents Cure system-Two-component Peroxide initiated Heat Resistance 302 degrees F (150 degrees C)

Physical Properties:
The physical properties of Liquid EPDM Liquid Rubber(R) are typical of its EPDM chemistry. The outstanding characteristics include:

1. Extreme high resistance to penetration of water, Ultra Violet and Ozone stable, excellent long term aging properties.
2. Very broad temperature tolerance range (from 300 degrees F to minus 62 degrees F). Acid and alkali resistant Withstands ponding water even when not cured

Spreading Rate:
A 20 mil dry film will result when liquid is applied at the rate of 42 sq. ft per gallon on a smooth surface.
A rate of 45 sq. ft allows for average roughness.
Weight/gallon 8 pounds (mixed)
Tensile 680 psi
Elongation 180-200%
Brittle Point -62 degrees F

Cure Mechanism: This rate is determined by temperature and the availability of oxygen. Oxygen is necessary to activate the catalyst, which promotes peroxide decomposition at lower temperatures. The cure mechanism in EPDM Liquid Rubber will vary from active to inactive determined by temperature. Broad day-night temperature swings in spring and fall will not compromise the final physical properties of the EPDM Liquid Rubber membrane.

Technical Properties of EPDM

Polymer Properties
1. Specific Gravity 0.87
2. ColorAvailable white or black

Vulcanizate Properties
1. Hardness, Durometer 30A to 90A
2. Tensile Strength, Mpa (psi)6.9 to 20.7 (1000-3000)
3. Elongation, %100-600
4. Compression Set B, %20-60 *
5. Useful Temperature Range-50 to 150ºC (-60 to 300ºF)
6. Brittle Point-50ºC (-60ºF) **
7. Volume Resistivity, ohm-cm1016 to 1017
8. Dielectric Strength,v/mil500-1000
9. Dielectric Constant2.2 to 3.0
10. Tear Resistance Fair to Good
11. Abrasion Resistance Good to Excellent
12. Resilience Fair to Good
13. Adhesion to MetalFair

Environmental Resistances
Ozone - Excellent
Oxygen - Excellent
Oils and Gasoline - Poor
Water - Excellent
Steam - Excellent
Oxygenated Solvents - Good to Excellent
Halogenated Solvents - Fair to Poor
Phosphate Fluids - Good to Excellent
Alkali's - Good to Excellent
Acids, Dilute - Excellent
Acids, Concentrated - Good to Excellent
Electrical Properties - Excellent

Features
Advantages Electrical Properties
Low Temperature Flexibility
Resistance to Weathering, Water, Steam, Heat
Cost
Limitations
Hydrocarbon resistance
Temperature above 177ºC (350ºF)
Flame Resistance

Since EPDM Liquid Rubber Coatings cures by chemical reaction, a single heavy application will be preferable to multiple thin coats. A second coat will bond to a previous film but that bond will not be as strong as the internal bond within each layer. If a second coat is applied before the first has thoroughly cured, some wrinkling may result as the first coat absorbs solvent and swells. This will, however, recover as the solvent evaporates. It is generally recommended that only a single coat be applied over non-porous surfaces, the thickness of which can be varied as desired. Thicker films will take longer to cure through. Asphalt coatings and asphalt built-up roofs are considered unstable substrates and therefore, not recommended for coating directly with Liquid Rubber EPDM. EPDM COATINGS do carry a specific elastomeric which with a two coat application gives you a 10 year warranty.
Liquid Rubber is designed to recoat structurally sound existing roof and protective materials. They are also best for RV Roof Repair. They should not be used in place of roofing membranes”.

The following are recommended substrates to coat:

• Metal – Coated or Galvanized Steel
o Weathered Aluminum
o Weathered Copper
• EPDM Rubber membrane
• Concrete (except foot traffic surfaces)
• Urethane Foam
• Primed Wood
• Fiberglass
• PVC Sheet and Pipe
• Acrylic Sheet
• Sponge Rubber insulation
Do Not use Liquid Roof or Liquid Rubber on the following substrates:
• Built up asphalt roofs
• Asphalt shingles
• Modified asphalt roll roofing
• Stainless steel
• Glass
• Silicone caulk
• Foot traffic surfaces
• Hypalon Membrane