Melting characteristic and β-crystal content of β-nucleated polypropylene/polyamide 6 alloys prepared using different compounding methods

Background: The distribution of nucleating agents in different phases is still an open question in general, and how to control conditions to prepare alloys rich in β-crystals of polypropylene (PP) is hardly reported. The main goal of this study was to find out the factors influencing the β-crystal content in β-nucleated PP/polyamide 6 (PA6) alloys and determine the best preparation conditions to obtain β-nucleated PP/PA6 alloys rich in β-crystals. Results: The compounding methods had little influence on the crystallization temperature of both PP and PA6. However, the melting characteristic and β-crystal content in β-nucleated PP/PA6 alloys not only depended upon the compoundingmethods, but also on the temperature at which the nucleating agent was added. A higher β-crystal content can be obtained by adding the nucleating agent at a temperature below 190 °C, which is also dependent on themixing time. Conclusion: It is proved by etching the alloys with sulfuric acid that the nucleating agent mainly disperses in the PA6 phase and/or the interface between PP and PA6 when blended at high temperature.