TY - CONF A1 - Chatzigiannakis, Emmanouil A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Schulze, Dietmar A1 - Wolff, Dietmar T1 - Influence of composition on the thermal ageing behaviour of EPDM N2 - Ethylene-propylenene-diene copolymer rubbers (EPDM) are used in a wide range of sealing applications e.g. in automotive industry or in containers for dangerous goods. Investigations with regard to the ageing behavior and lifetime prediction of commercial EPDM rubber seals consisting of 48 % polypropylene (PP) and 4.1 % of 5-ethylidene-2-norbornene (ENB) were conducted [1]. However, structural parameters (monomer ratio, diene type, curing agent etc.) and additives (filler, plasticizer etc.) are known to affect the ageing behavior of rubber compounds [2, 3]. The aim of the current study was to elucidate the influence of each component on the overall deterioration of material properties after thermal ageing. Therefore, different EPDM mixtures were prepared at BAM, the reference being an EPDM with 48 % PP and 4.1 % ENB reinforced with Sillitin. Five more formulations were prepared in order to assess the effect of (i) filler type (carbon black or sillitin), (ii) curing agent (sulfur or peroxide), (iii) plasticizer, (iv) ethylene-propylene ratio and (v) ENB content. Initially, the properties of the unaged materials were investigated by tensile testing, hardness and density measurements, TGA, DSC and DMA. Sulfur vulcanization resulted in higher elongation at break due to the flexibility of the sulfidic crosslinks. Carbon black resulted in better reinforcement compared to Sillitin. A higher ethylene and ENB content lead to higher hardness due to higher crystallinity and higher crosslink density, respectively. Thermal ageing for up to 30 days (with 10 days intervals) took place in circulating hot air ovens at 125 °C. Pronounced crosslinking was found to take place in all peroxide-cured materials, as the unreacted double bonds of the ENB units acted as starting points for oxidation and crosslinking. Increasing the ethylene content resulted in an increase in the ageing resistance of EPDM. This improvement was attributed to the higher crystallinity that inhibits oxygen diffusion and to the smaller number of chain scissions which occur in the PP units. Although significant loss of the plasticizer was observed, the remaining plasticizer adequately improved the tensile properties of the material. The filler type did not significantly affect the ageing behavior of EPDM. Finally, the lower thermal stability of the sulfidic crosslinks resulted in desulfurization and, thus, in an increase in the crosslinking density. To sum up, it has been shown that the monomer composition, curing agent and additives used in EPDM formulations greatly influence the properties and ageing resistance of these materials. T2 - 12. Kautschuk Herbst Kolloquium CY - Hanover, Germany DA - 22.11.2016 KW - Degradation KW - Elastomer KW - Compound PY - 2016 AN - OPUS4-38484 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -