Melting characteristic and beta-crystal content of beta-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 beta-crystals of polypropylene (PP) is hardly reported. The main goal of this study was to find out the factors influencing the beta-crystal content in beta-nucleated PP/polyamide 6 (PA6) alloys and determine the best preparation conditions to obtain beta-nucleated PP/PA6 alloys rich in beta-crystals. RESULTS: The compounding methods had little influence on the crystallization temperature of both PP and PA6. However, the melting characteristic and beta-crystal content in beta-nucleated PP/PA6 alloys not only depended upon the compounding methods, but also on the temperature at which the nucleating agent was added. A higher beta-crystal content can be obtained by adding the nucleating agent at a temperature below 190 degrees C, which is also dependent on the mixing 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. (C) 2009 Society of Chemical Industry