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Heat-resistant copolymer blends.

U.S. Patent 9,062,193 (June 23, 2015), "Heat Aging Resistant Ethylene Vinyl Acetate Copolymer Composition and Process for Its Production," Steven R. Oriani (E. I. Du Pont de Nemours and Company, Wilmington, Delaware, USA).

Oil-resistant ethylene vinyl acetate (EVA) copolymers are well-known synthetic materials formed by copolymerizing ethylene and at least 40 wt% vinyl acetate. These resins are used in wire and cable jacketing as well as in the production of automotive parts such as hoses and seals. Resistance to heat aging is necessary in under-the-hood applications, because they are exposed to temperatures above 160[degrees]C for hours, resulting in oxidative embrittlement.

There's a need to improve the high-temperature resistance of these copolymers. Oriani developed heat-resistant EVA copolymer compositions consisting of a blend of EVA copolymer, peroxide-curable polyacrylate elastomer, and polyamide. When crosslinked with a peroxide, this EVA copolymer material has enhanced resistance to heat aging. For example, replacing one quarter of the EVA material by a blend of polyacylate elastomer and polyamide reportedly can provide over five times greater elongation at break after one week heat aging at 190[degrees]C--and one-fifth the usual change in Shore 'A' hardness. Furthermore, these advantages in heat aging are gained with no sacrifice in compression-set resistance.

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Title Annotation:INDUSTRY PATENTS; patent received
Author:Corneliussen, Roger
Publication:Plastics Engineering
Article Type:Brief article
Date:Oct 1, 2015
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