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Chemical Composition.
Liquid Rubber is based on a low molecular weight terpolymer of Ethylene and Propylene with a pendant group of Dicyclopentadiene.The Ethylene-Propylene backbone is saturated and crosslinking takes place via the DCPD group.
Technical Data
* Volume Solids: 63.5%
* Spreading Rate A 20 mil dry film will result when liquid is applied at the rate of 50 sq ft per gallon on a smooth surface. A rate of 45 sq ft per gallon allows for average surface roughness.
* Theoretical Coverage: 1020 sq ft per gallon at 1 mil dry
* Weight/ Gallon: 8 pounds [mixed]
* Tensile: 680 psi
* Elongation: 180-200%
* Brittle Point: -62 degrees F.
* Permeability: 0.1 perm
* Weatherometr: 2000 hours[ASTM D4459-8-03]
* Peel Adhesion: 4.85 pounds per linear inch on Firestone EPDM.
* Pot Life: 4-10 hours depending on temperature.
Cure Mechanism.
Crosslinking takes place at ambient temperatures. Free radicals resulting from the decomposition of the organic peroxide cause crosslinking to take place at the DCPD sites. The rate at which the peroxide decomposes, therefore, determines the rate at which the system will cure. This rate is determined by temperature and the availability of oxygen. Oxygen is necessary to activate a catalyst which promotes peroxide decomposition at lower temperatures. The cure mechanism in EPDM Liquid Rubber will vary from active to inactive , determined by temperature. Faster cures and slow cures over extended periods of time result in identical physical properties. Broad day-night temperature swings in spring and fall will not compromise the final physical properties of the Liquid Rubber Membrane.
Physical Properties.
The physical properties of Liquid Rubber are typical of its EPDM chemistry.
The outstanding characteristics include:
1. Extremely high resistance to penetration of water
2. Ultra Violet and Ozone stable
3. Excellent long term aging properties (i.e. retains its flexibility and elongation longer than other elastomers );
4. Very broad temperature tolerance range [ from 300 degrees F to minus 62 degrees F]
5. Acid and alkali resistant
6. Resistant to polar solvents
7. Withstands ponding water even when not cured
8. Weakness-oils, fats and waxes will swell the polymer.
Application characteristics:
The slow curing and non-polar nature of EPDM Liquid Rubber give it outstanding surface wetting properties. The product does not fill cracks and crevices but will produce an even film penetrating even the smallest cracks and irregularities. An example of this is, when EPDM Liquid Rubber is applied over porous surfaces such as poured concrete, pinholes will appear on the surface as the material slowly displaces the air in the pores. This surface wetting feature enables the product to be applied in a single coat over non porous surfaces and still result in complete film integrity. EPDM Liquid Rubber is hydrophobic in its liquid as well as the cured state and will withstand water immersion at any stage of its cure cycle.
EPDM Liquid Rubber should not be used where the material does not have exposure to oxygen such as between two impervious materials. When oxygen is available curing takes place from both top and bottom of film. There is sufficient oxygen available on most surfaces to initiate cure from the bottom. Oxygen readily penetrates films 20 mils thick. Curing is considerably retarded in thick films, however, cures do take place in thicknesses up to 75-80 mils within a three month period at temperatures over 70 degrees F. EPDM Liquid Rubber can be applied to hot roof surfaces encountered during summer. The solvent in the system will flash off rapidly but the polymer will remain soft long enough to permit overlapping even after 1-2 hours. The cure rate is still controlled even at temperatures up to 120 degrees F and will not result in a porous film.The product can, therefore, be safely applied on the hottest day. The controlled cure rate also results in long pot life , giving the applicator more than an adequate length of time [ 4-6 hours depending on temperature] to use the mixed quantity of material.
Adhesion
Adhesion will increase over time. Polar surfaces such as metal, concrete and wood result in stronger adhesion than non-polar surfaces such as asphalts and single ply EPDM sheet. Most weathered surfaces including single ply and thermoplastic membranes will have enough of a surface profile to anchor the Liquid Rubber.
Durability
By itself, the Liquid Rubber membrane will exhibit the characteristics of its EPDM chemistry, i.e. U.V. and ozone stability, excellent ponding water resistance and long-term retention of flexibility. However, since it is always applied to an existing roof surface,the condition of that surface will determine overall life expectancy.
Liquid Rubber applied over generally sound single ply EPDM can extend its life another 20 years. The useful life of metal roofs also benefit greatly when Liquid Roof is applied. BUR systems often have existing problems such as delamination between layers, buckling and stress cracking. These are further aggravated by wet insulation which often results in severe corrosion and weakening of the metal supporting deck. Projecting a life expectancy for the EPDM Liquid Rubber membrane ultimately comes down to a case by case determination. When the EPDM membrane is compared to urethanes, acrylics and other elastomers in accelerated weathering and heat aging tests, the EPDM shows itself to be superior.
Color
White, Black, and custom colors. Custom colors are available for orders over 100 gallons.
Packaging
One and five gallon containers; drums available on request
Cure Rate
at 70 degrees F: 7-8 hours to touch
24-30 hours to walk on
5-7 days full cure
Thinner: Most aliphatic and aromatic hydrocarbon solvents [Mineral Spirits, VMaP Naphtha, Xylol]. Weaker solvents should be used when coating EPDM rubber sheet to minimize distortion.
Chemical Resistance: Cured EPDM rubber is resistant to acids, alkalis and polar solvents [Alcohols, Ketones, Glycols]. Oils and fats will soften the rubber and should be avoided.
Cure System: Two component Peroxide initiated
Heat Resistance: 302 degrees F [150 C] continuous exposure
VOC: 2.46 pounds per gallon [295/ grams liter]
