Air springs with improved high temperature performance

A process for preparing an air bellow, the process comprising the steps of:

• providing a masterbatch (a) that includes:
• EPDM,
• natural rubber, and
• one or more ingredients selected from the group consisting of plasticizers, tackifiers, waxes, antioxidants, fillers, oils, and curatives;
• providing a masterbatch (b) that is prepared separately and independently from masterbatch (a) and that includes:
• polychloroprene, a polychloroprene copolymer, or a mixture thereof, carbon black, and,
• one or more ingredients selected from the group consisting of plasticizers, tackifiers, antioxidants, fillers, and oils;
• combining the masterbatch (a), the masterbatch (b), and, optionally, one or more curatives, to form a vulcanizable composition, wherein the vulcanizable composition includes at least 30 parts by weight carbon black, per hundred parts rubber;
• fabricating an uncured air bellow having four layers, including an innerliner layer, a first ply layer, a second ply layer, and an outer cover layer, where at least one layer is fabricated from the vulcanizable composition;
• and
• at least partially curing the uncured air bellow.