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ELASTOMERS AND PLASTICS Investigation of the Post-Hardening Effect in a Silica filled NR-Compound

Von Frances van Elburg, Fabian Grunert, Auke Talma, Anke Blume, Enschede, The Netherlands Anne Risthaus, Damme, Germany 1 min Lesedauer

Storage hardening is an effect that commonly occurs in unvulcanized natural rubber (NR) compounds. In this study, the increase in hardness during storage of a vulcanized NR compound filled with silica was investigated. An increase in hardness during storage at room temperature and at 60 °C was observed.

Figure 1. Influence of the crosslink density on the vulcanizate properties. Figure adapted from [9].(Bild:)
Figure 1. Influence of the crosslink density on the vulcanizate properties. Figure adapted from [9].
(Bild:)

Unvulcanized natural rubber (NR) often becomes harder during storage. This storage hardening effect is caused by spontaneous crosslinking due to non-rubber chemical groups in the natural polymer [1]. However, the increase of hardness during storage of NR after vulcanization, referred to as the post-hardening effect, has not yet been investigated in detail. Natural rubber compounds are often used for damping applications, such as vehicle engine mounts. Excellent static and dynamic stiffnesses are necessary for these products, as well as good damping properties and energy absorption [2,3].