Toughening of polypropylene with β-nucleated thermoplastic vulcanizates based on polypropylene/ethylene-propylene-diene rubber blends

A series of dynamically vulcanized isotactic polypropylene (PP)/ethylene-propylene-diene rubber thermoplastic vulcanizates (TPVs) containing different content of beta-nucleating agent (beta-NA) were prepared and introduced into isotactic PP matrix as a toughening agent. The effect of beta-nucleated TPVs (beta-TPVs) on the toughness and other properties of PP were studied. Differential scanning calorimetry and wide-angle X-ray diffraction results indicated that the beta-crystallinity and the relative content of beta-phase in beta-TPVs samples and the toughened blends increased with the content of beta-NA increasing. The notched impact strength of PP toughened by beta-TPVs, with limited loss in the tensile strength and rigidity, showed an almost linear increase with increasing beta-NA content. Especially when the content of beta-NA was 0.5 wt%, the impact strength of the toughened blends was ten times more than that of pure PP. The toughening mechanism based on classical rubber toughening mechanisms was discussed and a synergic toughening mechanism was proposed. (c) 2013 Elsevier Ltd. All rights reserved.