Crystallization behaviour of heterophasic propylene-ethylene copolymer at rapid cooling conditions

The crystallization kinetic of neat and nucleated heterophasic isotactic propylene(ethylene-propylene) copolymer (iPP-EPC) was analyzed by fast scanning chip calorimetry. On cooling neat iPP-EPC shows two exothermic events, one related to the solidification of the iPP component followed by the crystallization of the polyethylene (PE) part in the copolymer. The effect of the type of nucleating agent on the kinetic of structure formation of the iPP matrix was observed only in the high-temperature range of isothermal crystallization. The detected decrease of the minimum crystallization half-time due to the addition of nucleating agent, from 0.12 s in case of the neat copolymer to 0.01 s in case of the nucleated iPP-EPC, is in parallel to the increase of the critical rate of cooling for suppression of crystallization from 200 to 1000 K/s, respectively. The efficiency of the different nucleating systems in iPP-EPC solidified at slow cooling was qualitatively analyzed by light microscopy. (C) 2016 Elsevier Ltd. All rights reserved.