Guomin Xu

Morphology and mechanical properties of polypropylene/ethylene acrylic acid/maleic anhybride-grafted polypropylene/organoclay nanocomposites: The role of compatibilizers and organoclay content

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 (T g), storage modulus (G″), T g, 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 T g, G″, tensile strength, flexural strength, and flexural modulus of the nanocomposites, whereas the T g 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.

Effect of Surfactant Concentration on Thermal and Mechanical Properties of Poly(Butylene Succinate)/Organoclay Composites

ABSTRACT Composite materials consisting of poly(butylene succinate) (PBS) and montmorillonite (MMT), modified to various extents using trihexyltetradecylphosphonium chloride (THTDP) cations, were prepared using a simple melt intercalation technique. The surfactant contents were varied, i.e. 0.4, 0.6, 0.8, 1.0, and 1.2 times the cation exchange capacity (CEC) of the MMT. The intercalation of the surfactant molecules into MMT layers, confirmed by the increase in interlayer spacing and significant changes in the morphology of the modified MMT, facilitated the dispersion of the clay in the PBS matrix. The properties of the PBS-based composites were changed with increasing surfactant content. The melting and crystallization temperatures increased and the degree of crystallinity (χc) decreased. The storage modulus was significantly enhanced below the glass transition temperature (Tg), and Tg shifted to a higher temperature, with a maximum at a surfactant loading of 0.6 CEC. The mechanical properties, including tensile strength, flexural strength, flexural modulus and impact strength, increased and then decreased with surfactant loading, with the maximum observed also at a surfactant loading of 0.6 CEC. In conclusion, an ideal balance between thermal and mechanical properties can be obtained at a surfactant quantity equivalent to 0.6 times the clay CEC. Moreover, all the composites exhibited obvious improvement in thermal and mechanical properties as compared to those of neat PBS.