Effect of polyhedral oligomeric silsesquioxane (POSS) reinforced polypropylene (PP) nanocomposite on the microstructure and isothermal crystallization kinetics of polyoxymethylene (POM)

In this study, effects of small amount of methyl-polyhedral oligomeric silsesquioxanes (methyl-POSS) on the microstructure and isothermal melt-crystallization behavior of polyoxymethylene (POM) were investigated, in detail. Introducing of methyl-POSS particles in POM phase was achieved via melt blending of methyl-POSS reinforced isotactic polypropylene (i-PP) nanocomposite as POSS carrier material with POM in a twin screw co-rotating extruder. Microstructural features of the POM/PP–POSS compounds were investigated with scanning electron microscopy (SEM) analysis. SEM analysis showed that the POM/PP–POSS compounds exhibited immiscible blend morphology. The POM, continuous matrix, phase includes a significant number of POSS particles due to interfacial interactions between the Si–O bonds of POSS and C–O bonds of POM, and resulted POSS migration from PP to POM phase during the melt processing. The kinetic parameters for the isothermal melt-crystallization process of the samples were determined with the Avrami and Lauritzen–Hoffman models. The crystallization activation energies were determined by the Arrhenius method. It was found that the PP–POSS nanocomposite significantly accelerated the isothermal crystallization rate of POM. Based on the results, it has been highlighted that POM compounds including a small amount of PP–POSS nanocomposite as POSS carrier material can be successfully used in the production of injection molded POM parts because the POM/PP–POSS compounds yield much faster molding cycle thus production rate than the POM.