Modeling of creep and recovery behaviors of isotactic polybutene‐1 melt

Abstract Isotactic polybutene‐1 (iPB‐1) has been widely used in various industrial and construction fields due to its excellent performances such as high‐temperature creep resistance, long‐term internal pressure resistance, and slow crack growth performance. However, relative to other polyolefins, the slow chain dynamics of iPB‐1 bring difficulties of much slower melt processing and molding. For example, there is a much slower extruding speed of iPB‐1 pipes in industries. To further understand the rheological properties of iPB‐1 melt during processing and molding, the creep and recovery behaviors of iPB‐1 melt under various applied shear stresses from 50 to 2000 Pa covering both the linear and non‐linear viscoelastic regimes at different temperatures from 200 to 160°C were carefully examined and fitted by the selected FE‐Burger, Findley, and Weibull models. Among the three models, the FE‐Burger model fits the creep process best; whereas, the Weibull model fits the recovery process best. As the recovery behaviors of iPB‐1 melt are closely related to the melt stability during extruding, the fitting parameters in the Weibull model dependent on temperature and the applied stress were determined and empirical equations had been established to provide a solution for further understanding and control of iPB‐1 melt processing and molding. The obtained accurate description of the creep and recovery behaviors of iPB‐1 melt via modeling is of great importance for iPB‐1 industrial processing and applications, which would shed light on the future promotions of iPB‐1 melt processing techniques. Highlights FE‐Burger model fits creep behaviors of iPB‐1 melt best. Weibull model fits recovery behaviors of iPB‐1 melt best. Empirical equations were established for iPB‐1 melt recovery behaviors. Extended n K‐Burger fits recovery behaviors of iPB‐1 melt well but is complex. Recovery behaviors of iPB‐1 melt reveal its melt stability while processing.