Synergistic effects of α/β-nucleating agents on propylene-ethylene random copolymer: New clues for the pipe extrusion

Adding -nucleating agents (-NAs) has been generally considered as an effective approach to induce the formation of -crystals in propylene-ethylene random copolymer (PPR). However, it is still difficult to obtain the expected percentage of -crystal under normal processing conditions, due to the temperature control is always a key factor no matter with or without adding -NAs. We assumed that simultaneously adding both - and -NAs to PPR in rational ratios would facilitate the growth of -crystal. The effects of adding various amount of - and/or -NAs on the - and -crystallization behavior and morphology were investigated. More importantly, the influence of temperature control on inducing -crystal in the presence of different NAs was parallel explored by utilizing sample bars prepared via injection molding and sample pipes produced from a typical industrial extrusion line. Different crystallization situations were carefully discussed in response to various nonisothermal crystallization processes in laboratory experiments and in actual pipes extrusion. At last, the mechanical properties of PPR samples were examined to provide new clues for further study of PPR pipes. POLYM. ENG. SCI., 56:1089-1095, 2016. (c) 2016 Society of Plastics Engineers