Morphology and mechanical properties of polypropylene/ethylene acrylic acid/maleic anhybride-grafted polypropylene/organoclay nanocomposites

Abstract

Polypropylene (PP)/ethylene acrylic acid (EAA)/maleic anhybride-grafted PP (PP- g-MA)/organoclay nanocomposites were prepared using the melt mixing technique, and PP- g-MA and EAA were employed as the compatibilizers. The sodium montmorillonite (MMT) were pretreated with high-speed airflow pulverization method and then grafted using γ-glycidoxypropyltrimethoxysilane, followed by modification using trihexyltetradecylphosphonium chloride cation with supercritical carbon dioxide as the reaction medium (the obtained product was abbreviated as OGMMT). The modification of MMT was characterized by thermogravimetric analysis, X-ray diffraction (XRD), and scanning electron microscopy. The effect of organoclay content on microstructure and mechanical properties of PP/EAA/PP- g-MA/OGMMT nanocomposites was investigated by XRD, transmission electron microscopy, dynamic mechanical analysis, tensile strength, notched impact strength, flexural strength, and flexural modulus. The results show that the OGMMT has a high weight loss, a large d-spacing increment, and exfoliation predomination structure. The addition of compatibilizers benefited the formation of exfoliated structure and the dispersion of OGMMT in PP matrix, and hence, enhanced the storage modulus ( G′) below the glass transition temperature ( Tg), storage modulus ( G″), Tg, tensile strength, flexural strength, and flexural modulus of the nanocomposites. Furthermore, with the increasing OGMMT content, the nanocomposites exhibited very inconsiderable alteration in the clay dispersion level and enhanced G′ below the Tg, G″, tensile strength, flexural strength, and flexural modulus of the nanocomposites, whereas the Tg was invariant. As a whole, the introduction of compatibilizers and OGMMT led to the reduction of notched impact strength, which also nearly linearly decreased with increasing clay content.