Crystallization behaviors of polypropylene/polyamide-6 blends modified by a maleated thermoplastic elastomer

Abstract

In this paper, with the maleated thermoplastic elastomer (TPEg) as a compatibilizer of polypropylene (PP)/polyamide-6 (PA6) blends, the effects of interfacial compatibilization on the crystallization behaviors of the blends were investigated by differential scanning calorimetry (DSC). Compared with the binary blend, the addition of TPEg significantly affected the crystallization behaviors of the individual component in the blends, especially those of PA6. The presence of TPEg weakened the nucleating role of the PA6 on the PP matrix. The increasing concentration of the compatibilizer caused a decrease in crystallization temperature (Tc) and crystallization enthalpy (ΔHc) associated with PA6. When TPEg amount was added up to 24 wt %, the crystallization of PA6 at its bulk Tc was almost completely suppressed and the complete concurrent crystallization of PA6 and PP matrix took place. In the case of PP/PA6/TPEg blend containing 24 wt % TPEg, it was found that the disappearance of bulk PA6 crystallization peak was independent of the cooling rate and annealing time, but can be introduced by self-nucleation experiments. The above fractionated crystallization phenomenon was attributed to the reduction in PA6 particle size due to compatibilization role of added TPEg, which leads to the lack of the active heterogeneities. The crystalline morphologies under isothermal conditions were also observed by polarized optical microscopy (POM).