Ethylene Vinyl Acetate elastomers applications

The use of these monomers for radiation cross-linking of polyethylene has been suggested [66]. With benzophenone as a photosensitizer, atactic as well as isotactic polypropylene is crosslinked with allyl acrylate by UV radiation. In this process both types of double bonds react [67]. Elastomers such as ethylene-vinyl acetate copolymer have been cross-linked with this monomer on a roller mill at 150°C using dicumyl peroxide as the initiator. Such cross-linked elastomers exhibit little or no swelling with aromatic solvents or chloroform after 24 hr at 30°C, conditions under which the uncured elastomers ordinarily dissolve [68]. Despite these interesting applications for such monomers, the bulk of the commercially produced allyl methacrylate finds application as a synthetic intermediate rather than as a monomer. 

Plastics find extensive use in several areas of fiber optic cables. Buffer tubes, usually extruded from high-performance plastics such as fluoropolymers, nylon, acetal resins, or polybutylene terephthalate (PBT) are used for sheathing optical fibers. A blend o PVC and ethylene vinyl acetate (EVA) polymer, such as Pantalast 1162 of Pantasote Incorporated, does not require a plasticizer, which helps the material maintain stability when in contact with water-proofing materials. PVC and elastomer blends, Carloy 6190 and 6178, of Cary Chemicals are also used for fiber optic applications (Stiffening rods for fiber optics are either pultruded epoxy and glass or steel. Around these is the outer jacketing, which is similar to conventional cable.)... 

The fundamentals of pressure-sensitive hot-melt adhesives are similar to those of solvent-based systems. Most elastomers and tackifiers are suitable, although ethylene-vinyl acetate copolymers are also used and the conventional rubber types are not. Pressure-sensitive hot melts are dominated by thermoplastic rubbers, which are ideal for use in these applications. Their unique properties arise from their essentially two-phase structure, in which thermoplastic regions of styrene end blocks lock the elastomeric midsections of butadiene or isoprene at room temperature but allow the elastomer to move freely at elevated temperatures or in solvent. This gives the polymer properties that are akin to those of vulcanized rubbers at room temperature, while allowinig it to behave as a thermoplastic when heated or dissolved. This structure is illustrated in Fig. 1. 

EVM finds application as wire insulation in the automotive industry. Ethylene vinyl acetate is also used in the production of thermoplastic elastomers as the soft phase. 

To achieve good toughness, required for many applications, impact modifiers are added to PVC. Chlorinated polyethylenes, ethylene-vinyl acetate copolymers, styrene-methyl methacrylate grafted elastomers, vinyl rubbers, and polyacrylates are the most frequently used (316). These polymers are blended together with other additives. Blending conditions are extraordinary important for morphology control and consequently for final properties of the blends. 

Blends of NR and ethylene-vinyl acetate copolymer (EVA) (physical blends and statically vulcanized) combine the good elastomeric and mechanical properties of NR with the excellent ageing and flex crack resistance of EVA. Blends of NR/EVA copolymer are becoming an important rubber/thermoplastic elastomer blend. Applications of these materials can be found in fields where... 

Rubbers and elastomeric products for practical applications are usually blends of different elastomer types that develop specific domain morphologies at the microscale, and, therefore, they are a part of this chapter. The most common representatives of the ruhher family are natural ruhher (NR) and the synthetic polyhutadiene ruhher (PB). There are various copolymers of butadiene with styrene (styrene butadiene rubber, SBR) or acrylonitrile (acrylonitrile-butadiene rubber, NBR). Several elastomers have been developed for special purposes, such as EVA (ethylene vinyl acetate copolymer), PU (polyurethane), EPDM (ethylene propylene terpolymer), and siUcone rubber. 

In the examination of potential applications for these unique materials that possess a wide variety of properties depending on copolymer composition, the Dow group examined finished articles formed by injection and blow molding, blown and cast film and melt extrusion. Potential applications for these new materials would be as substitute materials for flexible PVC, styrenic block copolymers, ethylene/vinyl acetate copolymers and ethylene/propylene-based elastomers. These new ethylene/styrene copolymers once again demonstrate that new catalyst technology creates new markets and applications for the polyethylene industry by competing with materials outside of the polyethylene product mix. 

Benefos 1680 is a secondary antioxidant. It is particularly useful in polyolefins and olefin-copolymers such as polyethylene, polypropylene, polybutene and ethylene vinyl acetate copolymers as wall as polycarbonate and polyamids. Other applications Include use in linear polyesters, high impact polystyrene, ABS, SAN, adhesives, natural and synthetic tackifier resins, elastomers such as BR, IR, euid other organic siibstrates. 

PBT is also blended with PMMA, PET/PC, and polybntadiene. Another development involving the use of PBT is coextrusion of PBT and copolyester thermoplastic elastomer. This can then be blow molded into under-hood automotive applications, which minimize noise vibration. PBT is suitable for applications requiring dimensional stability. It is particnlarly good in water, and it is also resistant to hydrocarbons oils without stress cracking. To improve PBT s poor notch impact strength, copolymerization with ethylene and vinyl acetate will improve toughness. 

---