Ethylene Vinyl Acetate elastomers goods

None of these rubbers has carbon-carbon double bonds. Consequently, they have relatively good aging properties, but, on the other hand, they cannot be vulcanized by the classical sulfur process. For this reason, some of these rubbers are cross-linked with the aid of peroxides, and, in this case, by polymerization of vinyl groups in the case of some silicone rubbers or by free radical transfer reactions in the case of ethylene/vinyl acetate or acrylic rubbers. Other speciality elastomers are cross-linked by reaction with diamines, for example, in the cases of acrylic, epichlorohydrin and fluorine rubbers. 

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... 

Vinyl Acetate—Ethylene Copolymers. In these random copolymers, the ratio of ethylene to vinyl acetate (EVA) is varied from 30—60%. As the vinyl acetate content increases, the oil and heat resistance increases. With higher ethylene content the physical strength, tensile, and tear increases. The polymers are cured with peroxide. The main properties of these elastomers include heat resistance, moderate oil and solvent resistance, low compression set, good weather resistance, high damping, exceUent o2one resistance, and they can be easily colored (see Vinyl polymers, poly(VINYL acetate)). 

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. 

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