Where huge companies failed, ProGuard managed to engineer a liquid version of the popular singly ply roofing material, EPDM. But what exactly is Liquid EPDM and why does its chemistry matter?
Hal, the inventor of Liquid Rubber know's EPDM's chemistry inside and out. And it's this deep understanding that meant he saw an opportunity when others didn't. But why pour years of research into turning singly ply EPDM into a liquid, when there's others on the market?
How EPDM rubber beats other roofing materials
- Great UV stability, meaning EPDM doesn't enbrittle with years of exposure under the sun
- Hydrophobic, giving intense waterproofing protection, unlike breathable coatings like silicone
- Elastomeric (containing polymers with viscoelasticity, having both viscosity and elasticity)
- Crosslinkable, meaning it reacts chemically to increase molecular weight
- Heat resistant, so remains flexible in extreme temperatures
- Great chemical and salt resistance
- Withstands ponding water 365 days a year
- Better weatherproofing than Nitrile, butyl, Isoprene, acrylic and other rubber compositions
But why make it into a liquid rubber?
- Easier application. A coating means no cutting to size or messing around with adhesives
- Seamless protection, meaning no joints or seams that act as vulnerabilities
- Versatile coating, able to coat corrugated or uneven surfaces that would be a nightmare with single ply
- Great adhesion to almost any surface, and can be combined with ProFlex primer on porous surfaces
EPDM Chemistry: The birth of an effective roof sealant
EPDM stands for Ethylene, Propylene and Dicylopentadiene. These are the building blocks that make it a popular weatherproofer. Turn it into a liquid, and then we've got all those benefits with the added advantage of a coating. Easy. Except one problem.
EPDM rubber sheets need to be moulded into shape, requiring high temperatures. But when you're up a roof you're unlikely to have a portable furnace with you, so how do we turn the liquid into a solid?
Hal recreated the required effect by altering the chemistry of EPDM, enabling the use of a catalyst that kickstarted the cure process. This meant Liquid Rubber EPDM could be kept in the tin for a long time, then mixed with the catalyst when about to be applied.
This was achieved through 'crosslinking', as Hal explains...
"Free radicals resulting from the decomposition of a 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.
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."
Liquid Rubber EPDM Cure and application characteristics
- Slow cure gives outstanding surface wetting properties
- Liquid Rubber does not fill cracks or crevices but will leave an even film that penetrates even the smallest surface irregularities
- If EPDM is applied over porous surfaces, pinholes appear on the surface as the material slowly displaces the air in the substrate-- Use ProFlex Primer to avoid this
- Liquid Rubber is hydrophobic in its liquid and cured state, so can withstand water immersion at any stage of the cure cycle
- EPDM Liquid Rubber requires oxygen to cure, so can't cure in between two impervious surfaces
- There is sufficient oxygen available on most surfaces to initiate cure from the bottom, so long as Liquid Rubber is applied at the correct thickness