Dynamically vulcanized nanocomposite thermoplastic vulcanizates (NC-TPVs) based on ethylenepropylene-diene rubber (EPDM) and melt intercalated hybrid of poly(propylene) (PP)/maleic anhydride grafted poly(propylene) (PP-g-MA) with organo-modified montmorillonite (org-MMT) were prepared. X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) examination have been performed to evaluate the extent of the intercalation, as well as to characterize the microstructure developed during dynamic vulcanization. The organocaly was better intercalated and dispersed in the PP matrix of the NC-TPV samples at low clay contents. The NC-TPV samples showed a matrix-disperse type of morphology in which the crosslinked EPDM particles appeared in the form of agglomerates covered by a layer of nanocomposite PP (NC-PP). The NC-TPV samples exhibited higher elastic modulus compared with similar but unfilled TPV sample in spite of the lower crystallization degree for the former. The storage modulus (G() of the molten NC-TPV proved to be highly frequency dependent. This was assigned to the formation of a nanoclay network structure by the NC-PP covered EPDM rubber particles.PP/EPDM-based thermoplastic vulcanizates with organoclay 979 a Enthalpy of the 100% crystalline PP is 209 J/g. T m , melting temperature; T c , crystallization temperature.

In situ melt dynamic vulcanization process has been employed to prepare electrically conductive polypropylene (PP)/ethylene-propylene-diene rubber (EPDM) (40/60 wt %) thermoplastic vulcanizates (TPVs) incorporated by expanded graphite (EG) as a conductive filler. Maleic anhydride grafted PP (PP-g-MAH) was used as compatibilizer and a sulfur curing system was designed and incorporated to vulcanize the EPDM phase during mixing process. Developed microstructures were characterized using scanning electron microscopy (SEM), melt rheomechanical spectroscopy (RMS), X-ray diffraction (XRD), and transmission electron microscopy (TEM) and were correlated with electrical conductivity behavior. For comparison, another class of TPV/EG nanocomposites was fabricated using a commercially available PP/EPDMbased TPV via both direct and masterbatch melt mixing process. Conductivity of the nanocomposites prepared by in situ showed no significant change during dynamic vulcanization till the mixing torque reached to the stationary level where micro-morphology of the cured rubber droplets was fully developed, and conductivity abrupt was observed. In situ cured nanocomposites showed higher insulator to conductor transition threshold (3.15 vol % EG) than those based on commercially available TPV. All electrically conductive in situ prepared TPV nanocomposites exhibited reinforced melt elasticity with pseudosolid-like behavior within low frequency region in dynamic melt rheometry indicating formation of physical networks by both EG nanolayers and crosslinked EPDM droplets.

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