Crystallization kinetics, spherulitic morphology, mechanical properties and heat resistance of β-nucleated impact-resistant propylene-ethylene copolymer

•β-NA increases the crystallization rate and decreases Kg and σe of IPC.•The addition of β-NA decreases activation energy of non-isothermal crystallization.•The nucleating activity of NT-C is superior to that of NT-A.•The addition of β-NA decreases the spherulitic size significantly.•The toughness and heat resistance of IPC are improved by β-NA.

β-nucleated impact-resistant propylene–ethylene copolymer (IPC) samples were prepared via melt compounding. The isothermal and non-isothermal crystallization and melting behaviors of the samples were investigated by means of differential scanning calorimetry (DSC). Avrami equation was used to analyze the isothermal crystallization kinetics of the samples. The Lauritzen–Hoffman theory was applied and the nucleation constant Kg and the surface free energy σe was calculated. Jeziorny’s and Mo’s methods were used to analyze the non-isothermal crystallization kinetics of the samples. The activation energy (ΔE) of non-isothermal crystallization and the nucleating activity of the samples were calculated by Friedman’s formula and Dobreva’s method, respectively. The results show that the addition of β-nucleating agent (NT-A and NT-C) decreases the Kg and σe, so that the nucleation and crystallization rate of IPC is increased greatly under isothermal condition. Jeziorny’s and Mo’s methods well describe the non-isothermal crystallization kinetics of the samples. NT-C is more effective than NT-A as a β-nucleating agent. It is also found that the addition of nucleating agent decreases the size and increases the number of spherulites significantly. The Izod notched impact strength and heat deflection temperatures (HDT) of IPC are also improved by the nucleating agents.