History of EPDM (Ethylene-Propylene-Diene-Monomer)
There are many different types of EPDM roofing materials on the market today. Some of the most common materials include; shingles, metal decking, single ply systems, built-up systems, and single or double component liquid coatings. Each roofing material has its own performance function and cost that makes it unique. Some materials are sophisticated, and high-tech and expensive while others are less sophisticated low-tech and obviously more affordable Expensive, high tech and sophisticated roofing materials require skill to install, and usually at longer than low tech materials.
Regardless of the roofing materials you choose to install, there is still a probability that some failures will occur resulting in leaks. These failures are usually caused by factors such as faulty material, improper installation, roof penetrations that aren't adequately sealed and so on. Some thermoplastics and single ply roofing membranes (i.e. Hypalon and SHEET EPDM rubber) were believed to offer permanent solutions to leaking roofs however this hasn't been the case over the past few decades. These membrane systems haven't performed as expected as most of them last depending on the quality of their seam seals which are bonded using adhesives or heat when using thermoplastics.
Both seam seal methods demand clean contact surfaces and matching dimensions to avoid wrinkles. Some roofs, for example sloped roofs, can last with imperfect seam seals. However, flat roofs which develop ponding water can't handle imperfect seam seals. Other common factors that contribute to roofs developing leaks include; number of joints and number of seams.
Liquid Elastomeric Coatings and EPDM Rubber Coatings exist to repair leaks thus extending the life of a roof. These products are among the 4 generic types of coatings for ambient cure:
EPDM Single Ply Membranes
Hypalon synthetic rubbers and EPDM were first introduced into the United States between 1955 and 1965. Hypalon has a polymer polyethylene backbone which is inert and converted to a semi-crystalline or an amorphous polymer with elastomeric characteristics through chlorosulfonation and chlorination.
EPDM and EPDM Rubbers are made of copolymers and ethylene propylene which are all polymers. These polymers undergo compounding with fillers, plasticizers and catalysts to form sheets which are vulcanized afterwards to produce cured elastomeric membranes.
How Liquid EPDM Rubber Differs from Vulcanized EPDM
Liquid Rubber is composed of an ethylene terpolymer and propylene (a dicyclopentadiene pendant group).The backbone of Ethylene-Propylene is saturated and cross linking happens through the DCPD group. The low molecular polymer is dissolved in a solvent and then compounded with curatives and pigments which enable curing at appropriate temperature.
Liquid Rubber Cure Mechanism
Cross linking happens at ambient temperatures. The free radicals formed during peroxide decomposition are responsible for causing cross linking at DCPD sites. The rate of peroxide decomposition therefore determines the rate of curing of the system. This rate is in turn determined by the availability of oxygen and temperature. Oxygen is important for activating a catalyst responsible for promoting peroxide decomposition at low temperatures.
EPDM Liquid Rubber cure mechanism varies i.e. active to inactive. This variation is determined by temperature. Slow and faster cures over extended time periods cause identical physical properties. It is important to note that broad day and night temperature swings that are experienced during spring and fall don't compromise/affect the final EPDM Liquid Rubber membrane physical properties.
It is also important to note that there is enough substantial performance data about EPDM and EPDM rubbers accumulated over the last three decades. The polymers have proven themselves in automotive, roofing and industrial applications.
EPDM Curing Systems
For years the roofing industry has been battling the issue with cross linking and a proper cure or drying material when linking EPDM polymers. Finally in early 1990 one such polymer was developed and made available for wide range commercial usage. Over the years Liquid Rubber has been universally the roofing sealant used by the industry due to that very particular cross linking ability. The characteristics of the material make is second to none. Liquid EPDM has proven itself to outperform and out last any other roof coating in the industry.
The EPDM Liquid Rubber cure mechanism is known as initiated free radical polymerization. The catalyst for this mechanism is an organic peroxide because it produces the most appropriate cured properties resulting in a longer pot life.
The primary advantage to Liquid EPDM is its overall weatherability, the fact that it waterproofs immediately on application and at temperatures above 55 degrees will even cure under water. It is also the only product to take significant temperature swings so if you have a daytime high of 55 and at night it goes well below zero there is no need to worry about the durability and performance of the Liquid EPDM rubber. Also as the only roofing sealant able to tolerate ponding/standing water 365 days a year it is a relief for our customers with flat roofs. The final dry film is also resistance to acids and alkalis.