Ethylene—propylene-diene monomer applications

Process systems handling polymers and resins (e.g., butyl rubber or ethylene-propylene diene monomer rubbers) are often subject to plugging at dead-end locations such as PR valve inlets. In extreme cases, complete blockage of inlet piping and valve nozzle can result. This problem can be eliminated by the application of a flush-seated PR valve, in which dead-end areas are eliminated by placing the valve disc flush with the vessel wall, in the flow pattern of the contents. 

Ethylene-propylene diene monomer (EPDM) rubbers are used in mass predominantly in isolation systems such as CRFM (condenser, radiator, fan module) or engine mounting. More varied are the sealing applications, which include transmission seals and o-rings, HVAC module seals and gaskets, radiator seals, weather stripping... 

Several elastomers including Neoprene, polyurethane, silicone and ethylene-propylene-diene monomer rubber were tested according to the UL 94 VO procedure. Each material was exposed to flame for two, one second intervals. To pass the test, each individual specimen had to cease burning 10 seconds after flame application. Of these, only a cellular silicone called Bisco passed while another manufacturer s silicone severely charred and supported a flame. 

Accelerated-sulfur vulcanization is the most widely used method. For many applications, it is the only rapid crossUnking technique that can, in a practical manner, give the delayed action required for processing, shaping, and forming before the formation of the intractable vulcanized network. It is used to vulcanize natural rubber (NR), synthetic isoprene rubber (IR), styrene-butadiene rubber (SBR), nitrile rubber (NBR), butyl rubber (HR), chlorobutyl rubber (ClIR), bromobutyl rubber (BUR), and ethylene-propylene-diene-monomer rubber (EPDM). The reactive moiety for all of these elastomers can be represented by... 

Use of nanoparticles as fillers in mbbers is highly relevant because end use applications of rubber compounds require filler reinforcement. Most of the literature on rubber nanocomposites is based on the use of nanoclay as the filler. It has been shown that incorporation of nanoclay in synthetic rubbers, like styrene butadiene rubber (SBR), chloroprene rubber (CR), nitrile rubber (NBR), ethylene propylene diene monomer (EPDM) mbber etc. enhances the mechanical, anti-ageing and barrier properties. 

Although woven fabrics can be impregnated and coated in bitumen to give a bituminous geomembrane (BGM), the geomembranes widely used as impervious sheets are largely made from high-, medium-, and low-density polyethylene (HDPE, MDPE, LDPE), but PP, ethylene propylene diene monomer (EPDM) and PVC are used as alternatives for some applications. 

FKMs are coextruded with lower-cost copolymers such as etliylene acrylic copolymer. They can be modihed by blending and vulcanizing with other synthetic rubbers such as silicones, ethylene propylene rubber (EPR) and ethylene propylene diene monomer (EPDM) rubbers, epichlorohydrin, and nitriles. Fluoroelastomers are blended with modihed nitrile butadiene rubber (NBR) to obtain an intermediate performance-cost balance. These blends are useful for underhood applications in environments outside the engine temperature zone such as timing chain tensioner seals. Fluoroelastomers can also be blended with fluorosilicones and other high-temperature polymers to meet engine compartment environments and cost-performance balance. 

For flexible sheeting, as single ply roofing use, PVC and ethylene-propylene-diene monomer (EPDM) are expected to be the main polymers used. For wall and floor coverings PVC is still expected to continue to dominate the construction market. PVC will be the main plastic used for pipe and conduit, wire and cable, profiles and flooring applications, while EPS will be mostly used in insulation. 

Polychloroprene, nitrile, natural rubber (polyisoprene), styrene butadiene rubber (SBR) and butyl are amongst the types of rubber that can be readily bonded with cyanoacrylates. Ethylene propylene diene monomer (EPDM) and fluroelastomers (Viton, registered trade mark of DuPont) can also be bonded, although only with specific grades of cyanoacrylate. Silicone rubber and thermoplastic rubber (Santoprene, registered trade mark of Advanced Elastomer Systems) can be bonded with the aid of a primer. Typical applications and techniques for bonding different grades of rubber are discussed in Section 10.11. 

Exterior door handles are another application that has turned to plastics to balance chemical resistance and mechanical properties. Many filled thermoplastics such as blends of PC and polybutylene terephthalate (PBT), polyethylene terephthalate (PET), and nylon have been tried or used in this application, with nylon as the clear wirmer. Exterior mirror housings likewise use many thermoplastic solutions such as ABS, PC/ABS, blends of polyphenylene oxide (PPO) and polystyrene (PS), nylon, blends of PP and ethylene propylene diene monomer (EPDM), and weatherable ABS. Again, nylon clearly dominates this application in terms of volume. Many other exterior parts continue to adopt thermoplastic solutions. Figure 14 shows an impingement shield constructed from LGF PP. 

In nontire applications, there has been a faster growth in the use of synthetic rubbers such as ethylene-propylene-diene monomer (EPDM) and nitrile rubbers, as a substitute for SBR. However, nontire uses for SBR are growing with applications including conveyor belts, gaskets, floor tiles, footwear, and adhesives. 

Polypropylene is another polymer materials which has large areas of applications. The presence of propyl moieties, where the tertiary carbon atoms represents the possible places for degradation is the main factor taken into consideration for estimation of durability. The comparison between polyethylene, polypropylene and ethylene-propylene-diene monomer was reported and the criterion of stability is... 

Rubbers are polymers with large engineering application areas. The weathering oxidation progresses in the elastomers according with the namre of substrate. A comparison between styrene-butadiene mbber (SBR), ethylene-propylene-diene monomer (EPDM), chloroprene mbber (CR) and natural rabber (NR) [109] allowed stating some relevant outlines ... 

Delor-Jestin, F., Lacoste, J., Barrois-Oudin, N., Cardinet, C., Lemaire, J. Photo-, thermal and natural ageing of ethylene-propylene-diene monomer (EPDM) rubber used in automotive applications. Influence of carbon black, crosslinMng and stabilizing agents. Polym. Degrad. Stab. 67, 467-477 (2000)... 

It is explained that acrylic coagents can improve processability and vulcanisation of elastomers used in automotive applications, and that Saret coagents from Sartomer Co. of the USA provide scorch-retarding properties along with improved radiator hose properties for all curing situations. This article describes tests comparing several coagents in ethylene propylene diene monomer radiator hose formulations. Results are presented and discussed. 

Thioureas mainly find use for the vulcanisation of CR, epichlorohydrin (ECO) and some ethylene propylene diene terpolymer (EPDM) compounds. They show high crosslinking activity, with usually adequate compound flow time before onset of the crosslinking. In EPDMs, the thioureas are used as activators for low activity third monomer types and, in the presence of calcium oxide desiccants, in free state vulcanisation of extrudates, etc. The use of thioureas can overcome the retardation caused by the desiccant. In this case some care must be taken otherwise overcompensation may occur. Thioureas are not used in food product applications and are a known health hazard, particularly for pregnant women. 

Elastomers or rubbers are flexible materials that are mainly used in tires, hoses, and seals as adhesives or as impact modifiers of thermoplastics. They exhibit high resistance to impact, even at low temperatures at which materials increase their rigidity. Eor some of the applications (e.g., tires or hoses), these materials have to be slightly crosslinked once they are formed into the desired shape in order to impart them dimensional stability, since otherwise they tend to slowly flow. Elastomers are polymers that are used above their glass-transition temperature (Tg). Some examples of common elastomers are polybutadiene, which is used as an impact modifier of rigid plastics SBR (copolymer of styrene and butadiene), mainly used in tires EPDM (copolymer of ethylene, propylene, and a diene monomer, usually norbornene) NBR (copolymer of acrylonitrile and butadiene) and so on. 

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