| Summary: | Nanocomposites are a new class of mineral-filled plastics that contain relatively small amounts
(<10%) of nanometer-sized clay particles. Production of rubber-based nanocomposites
involves melt mixing the base polymer and layered silicate powders that have been modified
with quaternary ammonium salts. In this study, new 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 in contents of 2.5, 5, and
10 phr. Five types of clays (Cloisite 15A, 20A, 25A, 10A and 93A) were investigated during
this study and their influence on the thermal and mechanical properties of the rubber was
compared.
The degree of exfoliation or intercalation of the organoclays in the PCP nanocomposites was
investigated using x-ray diffraction spectroscopy (XRD) and transmission electron microscopy
(TEM). The results for Cloisite 93A and 15A depicted an exfoliated structure and a welldispersed
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 tensile modulus
was found to increase with an increase in clay content for all the nanocomposites, while tensile
strength and elongation at break decreased. The initial stage of thermal degradation was
accelerated with the incorporation of organoclays. The TGA results show that Cloisite 15A and
93A have a significant influence on the PCP degradation mechanism, even at low clay
contents. The properties of the PCP/clay nanocomposites were also determined by dynamic
mechanical analysis (DMA) and stress relaxation. Cloisite 15A and 93A containing
nanocomposites were generally found to have better properties than the other samples. This
could be due to these clays having stronger interactions with the PCP rubber.
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