EPDM membranes materials

There are special applications where it is required that essentially no dissolution or reaction takes place between the membrane/module material and the process stream. One such application area is food and beverages. For these uses, not only the membrane material but also the housing and gasket materials need to pass certain tests for sanitary reasons (e.g., FDA approval). Stainless steel (especially the 316L type) is typically used as the casing material and fluorinated polymers, EPDM, silicon or other specialty... 

EPDM roof sheet is one of the lightest roof membrane materials because of its low specific gravity. It is highly suitable for lightweight structures and puts negligible extra load on the roof to be waterproofed. It is serviceable over a wide range of temperatures -50 °C to 150 °C, and the membrane does not embrittle in freezing condition nor soften in hot weather. 

Table 3.6 Comparative properties of EPDM membrane versus other materials ...

Since little research had been reported on the application of thermal analysis (TA) methods to roofing, the committee recommended that more research be carried out to provide the technical basis for this application. The recommendation was based on research by Farlling and Backenstow and Flueler.I J These authors used TG, DSC, and DMA to characterize EPDM, PVC, and polymer-modified materials. Backenstow and Flueler reported the application of torsion pendulum analysis to characterize the above membrane materials. They concluded that TA techniques were useful for membrane characterization and should be investigated as methods for incorporation into standards. Previous work published by Cash on the use of DSC to characterize neoprene, chlorinated polyethylene (CPE) and PVC had shown that DSC could be used to identify not only the components in a single-ply sheet and the manufacturer, but also to differentiate between new and exposed materials. 

In 1990, Gaddy, et al., " conducted a study to provide data on the feasibility of using thermoanalytical methods to characterize roofing membrane materials. The authors used TG, DSC, and DMA to analyze white and black EPDM before and after laboratory exposure to heat, ozone, UV, and outdoor exposure. The results were compared to changes in load-elongation... 

For example, more and more manufacturers, contractors, consultants, and building owners are turning to these techniques to solve in-service roofing membrane problems as well as to evaluate new roofing membrane materials. A typical example is the paper on the problem of EPDM membrane shrinkage The study was conducted in 1995 to investigate the causes of... 

Gaddy, G. D., Rossiter, W. J., Jr., and Eby, R. K., The Use of Thermal Mechanical Analysis to Characterize Ethylene-Propylene-Diene Terpolymer (EPDM) Roofing Membrane Material, Materials Characterization by Thermomechanical Analysis, (A. T. Riga and C. M. Neag, eds.), pp. 168-175, ASTM STP 1136, ASTM, Philadelphia (1991)... 

At this point in the process, thermoplastic and chlorosulfonated polyethylene (CSPE) membranes are complete and are ready for packaging. In the case of ethylene—propylene—diene monomer (EPDM), the curing step occurs before the membrane is ready for packaging. The curing process is accomphshed by placing the membrane in a large vulcanizer where the material is heated under pressure to complete the cure. 

EPDM is by far the most widely used material in the ballasted roofing system constmction. Because of EPDM s flexibiHty, very large sheets of up to 10,000 square feet (929 m ) can be deHvered to the job site in compact roUs that offer reduced labor on the roof in the seaming process. The typical EPDM sheet size used in ballasted systems is 12 by 30 m and 1.1 mm thick. EPDM is also widely used in both the fully adhered and mechanically fastened roofing systems. In these constmctions, both 1.1- and 1.5-mm thick material is used with widths from 2.1 to 15 m. A majority of the installations use nonreinforced sheet, although reinforced membrane can also be used in all of the system types. The majority of the reinforced sheets go into mechanically fastened systems. 

Thermoplastics. There are five elastomeric membranes that are thermoplastic. Two materials, chlorinated polyethylene (CPE) and polyisobutylene (PIB), are relatively obscure. Thermoplastic materials can be either heat-fused or solvent-welded. In contrast to Hypalon and uncured EPDM, this abiHty to fuse the membranes together remains throughout the life of the material. However, cleaning of the membrane surface after exposure to weather is required. Correct cleaning procedures for specific membranes are available from the individual manufacturer. 

More than 800 million pounds of EPM and EPDM polymers were produced in the United States in 2001. Their volume ranks these materials fourth behind styrene-1,3-butadiene copolymers, poly( 1,4-butadiene), and butyl rubber as synthetic rubbers. EPM and EPDM polymers have good chemical resistance, especially toward ozone. They are very cost-effective products since physical properties are retained when blended with large amounts of fillers and oil. Applications include automobile radiator hose, weather stripping, and roofing membrane. 

Polymeric Materials. The single-ply membranes are made from a wide variety of polymers. The following is a brief description of those polymers and their characteristics. There are three thermosetting-type elastomeric membranes as of this writing (1996) neoprene, CSPE, and EPDM. Neoprene is still used where oil resistance is needed. For instance, Hydrotech uses neoprene flashings, the base of which is hot-set in rubberized asphalt (see Elastot rs, synthetic-polychloroprene). 

During the last decade many new roofing materials were introduced which are applied in the form of weldable membranes, liquid curable materials, self-adhesive products, and torchable materials. These materials are produced from numerous polymers such as, PVC, chlorinated polyethylene, chlorosulfonated polyethylene, EPDM, acrylics, bitumen, polymer-reinforced bitumen and several other materials. It is beyond the scope of this book to analyze compositional changes in these materials. We will provide a brief overview. 

The pressure chamber consists of a perforated candle filter. On top of the screen is a filter cloth and a membrane constructed of EPDM, BUNA, or Viton. At present these are the only available materials of construction. The... 

Although the material most used for single-ply membranes is EPDM, in competition with it are several other materials— Du Pont s Hypalon (a chlorosulfonated polyethylene), its Neoprene products, and modified PVC. It is believed that future growth in the roofing market will depend on products, such as Hypalon, that are easy to handle and have good ozone resistance, and on PVCs modified with polymeric plasticizers. 

Stainless steel is used as a construction material for support plates for the membranes and for spacers. Chemically stable elastomeres, like EPDM or per-fluorinated polymers are used as gasket material, more widely used is expanded graphite, due to its excellent chemical and thermal resistance. Preferentially the... 

Thermoset membranes are compounded from rubber polymers. The most commonly used polymer is ethylene, propylene and a small amount of diene that is vulcanized with various accelerants. This polymer, referred to in the industry as EPDM, is commonly known as rubber roofing . Another thermoset rubber roofing material is neoprene, although this particular formulation is rapidly being replaced by EPDM. Finally, the rubber/plastic hybrid Hypalon is also considered as thermoset. Hypalon is unique in that it is manufactured as a thermoplastic but, because it cures over time, becomes thermoset. 

PVC and PE have played a major role in the shift of early roof waterproofing technology and materials. After the introduction of elastomeric and other thermoplastic materials, flexible membranes of polychloroprene (Neoprene) rubber, butyl rubber and Hypalon were used. Later on, liquid PU, solvent-based liquid acrylate and liquid EPDM systems, in addition to new materials like SBS modified bitumens, were also used in the management of roofing. All fall into the single-ply family of roofing, which offers a much cleaner, safer, energy-efficient and cost-effective alternative to built-up roofs. 

To meet these desirable properties, the appropriate polymer to consider would be ethylene - propylene-diene terpolymer (EPDM). In the manufacture of a cost effective, impermeable membrane system, EPDM rubber is the right choice as a discreet material for improved waterproofing and protective lining applications in roofing and other uses in the construction sectors [125]. 

Over time it is far more economical than traditional waterproofing systems. A single layer membrane of thickness of 1.2 mm made from EPDM rubber provides superior waterproofness than multi-layer traditional material systems. 

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