Material BehaviourPolychloroprene nanocomposites filled with different organically modified clays: Morphology, thermal degradation and stress relaxation behaviour

Nanocomposite materials were produced from polychloroprene rubber (PCP) as the matrix and organically modified montmorillonite clays as fillers by using a two-roll mill. PCP was mixed with the clays at contents of 2.5, 5, and 10 phr. Five types of clay (Cloisite 15A, 20A, 25A, 10A and 93A) were investigated and their influence on the morphology, thermal stability and stress relaxation properties of the rubber was compared. The degree of exfoliation or intercalation of the organoclays in the PCP nanocomposites was investigated using x-ray diffractometry (XRD) and transmission electron microscopy (TEM). The results for Cloisite 93A and Cloisite 15A depicted an exfoliated structure and a well-dispersed morphology in the polymer matrix at all filler contents, while complete exfoliation was not observed for the other clays, especially at higher clay contents. The initial stage of thermal degradation was accelerated with the incorporation of organoclays. The TGA results show that Cloisite 15A and Cloisite 93A have a significant influence on the PCP degradation mechanism, even at low clay contents. Cloisite 15A and Cloisite 93A containing nanocomposites were generally found to have better stress relaxation properties than the other samples.