Modeling of polystyrenic nanoparticles driven β-trans-crystalline efficiency in isotactic polypropylene

摘要

Addition of 2 wt% mono-size, 180 nm in diameter, soft nanoparticles (SNPs) of linear and cross-linked polystyrene (PS and XPS) and styrene–acrylonitrile copolymers containing 25 wt% acrylonitrile (SAN25 and XSAN25) induced relative β-polymorphism as much as 20, 27, 34 and 10%, respectively, during 10 minutes annealing of isotactic polypropylene (iPP) at 116 °C. It became nil, however, by changing the annealing conditions: time and/or temperature. The β nucleation efficiency of the studied SNPs were modeled based on their normalized phenyl groups surface accessibility to the methyl groups of matrix chains profusion divided by the main components commensuration mismatch multiplied or divided by absolute particle rigidity at the crystallization conditions. A bi-exponential function with four constants could be fitted over the extracted data points rationalizing the kinetic and thermodynamic aspects of the phenomenon.