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The additive manufacturing (AM) of elastomeric parts based on high-viscosity reinforced rubbers has increasingly become a topic of scientific research in recent years. In addition to the viscosity, which is several decades higher during processing than the viscosities of thermoplastics, the flowability of the compound after the printing process and the necessary chemical crosslinking of the printed component play a decisive role in producing an elastic, high-quality, and geometrically stable part. After the first technological achievements using the so-called additive manufacturing of elastomers (AME) process, the knowledge gained has to be transferred first to concrete industrial parts. Therefore, in this study, the cure kinetics of a conventional rubber compound are tailored to match the specific requirements for scorch safety in the additive manufacturing of an industrial 2-component rod seal based on an acrylonitrile butadiene rubber O-ring in combination with a thermoplastic polyurethane as the base body. Experimental tests on a test rig for rod seals demonstrate the functionality of this additively manufactured 2-component rod seal. [ABSTRACT FROM AUTHOR]

Modern rubber materials face high demands in terms of oxidation stability as well as thermal resistance and, in some cases, enhanced oil resistance. At the same time, their mechanical properties have to maintain a high level. Highperformance synthetic rubbers with highly sophisticated properties – like nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR) and peroxide-crosslinked ethylene – propylene – diene rubber (EPDM) – are thus becoming more and more important. Nevertheless, irreversible aging processes limit lifetime and result in the failure of these elastomer materials. Knowledge about chemical aging mechanisms, kinetics and the weak elements in the polymer chain and in the chemical network are fundamental to understanding and predicting lifetime as well as in arriving at appropriate measures for stabilizing the polymer matrix. Alongside the polymer’s microstructure, other determining parameters are temperature, exposure to oxygen, and its diffusion into the bulk in competition to reaction speed, which is responsible for the spatial changing of the material from the surface inward. Investigations by means of selected methods like nanoindentation, FT-IR spectroscopy, chemiluminescence, and physical testing in combination with artificial aging are used to describe quantitatively the mechanistic role of the polymer’s microstructure and of crosslinking during thermal-oxidative aging. [ABSTRACT FROM AUTHOR]