Synergistic effects of nano-scale polybutadiene rubber powder (PBRP) and nanoclay on the structure, dynamic mechanical and thermal properties of polypropylene (PP)

Nano-scale polybutadiene rubber powder (PBRP) was prepared by spray drying of irradiated rubber lattices vulcanized by Co-60 radiation. Then, polypropylene (PP)-based nanocomposite samples using either PBRP or organoclay (OC) or both of them were prepared by melt mixing method. The prepared samples were characterized by performing mechanical (tensile properties and impact resistance), dynamic mechanical (DMTA), X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) tests. TEM micrographs verified a fine dispersion of the PBRP in the polymeric matrix which resulted to an enhancement in impact resistance of PP in spite of reduction in tan delta peak in DMTA test. By the way, the XRD and TEM tests showed that by the addition of PBRP, the interlayer space of the OC was increased and caused improvement in tensile properties of the PP/OC nanocomposite. Furthermore, mechanical studies revealed the synergistic effect of use of OC and PBRP together, thus, combination of OC with 5 wt% PBRP not only increased the toughness of the PP compared to the use of either of them, but also improved the tensile strength and elongation-at-break values. The DSC tests showed that the PBRP acted as a nucleating agent and promoted the crystallinity, melting temperature (T-m) and crystallization temperature (T-c) of the PP in nanocomposites.