Abstract: A copolymer of nylon 6 (caprolactam mer units) and nylon 12 (dodecanolactam mer units) and/or nylon 11 (undecanolactam mer units), which has been modified to provide improved physical properties, such as flex modulus, elastic modulus, and yield strength, serves as a layer of a hose suited to use in airbrake applications. The modified copolymer is resistant to degradation by zinc chloride and moisture and thus may be used as a peripheral layer of the hose in place of a conventional protective layer comprising a pure polyamide, such as nylon 11 or 12. Alternatively, the modified copolymer may be used as a tie layer for rendering a peripheral layer comprising nylon 12 or 11 compatible with a layer of nylon 6, allowing the less expensive nylon 6 material to comprise the bulk of the hose thickness. The layer includes a compatibilizer, such as a maleic anhydride grafted polyethylene, and may also include plasticizers and impact modifiers.

Abstract: A compounded alloy of nylon 6 and nylon 12 serves as a layer of a hose suited to use in airbrake materials. The alloy is resistant to degradation by zinc chloride and moisture and thus may be used as a peripheral layer of the hose in place of a conventional protective layer comprising a pure polyamide, such as nylon 11 or 12. Alternatively, the alloy may be used as a tie layer for rendering a peripheral layer comprising nylon 12 compatible with a layer of nylon 6, allowing the less expensive nylon 6 material to comprise the bulk of the hose thickness. The alloy includes a compatibilizer, such as a maleic anhydride grafted polyethylene in sufficient amount to render the alloy compatible with adjacent layers, thus avoiding the need for an intermediate layer of an adhesive. One or more of plasticizers and impact modifiers are preferably also present in the alloy to provide improved strength and flexural characteristics.