Effects of Blending Sequence on Morphology and Mechanical Properties of Polypropylene/Ethylene-octene Copolymer/Clay Nanocomposites

Sedigheh Bagheri Kazemabad,Biqiong Chen,Alireza Khavandi,Hongzhou Zhang,Yanhui Chen,Daniel Fox

doi:10.13189/mst.2015.030507

Abstract

The objective of this study was to investigate the effects of three blending sequences on morphology and properties of the ternary nanocomposite of polypropylene (PP)/ethylene-octene copolymer (EOC)/clay with double compatibilizers of maleated PP (PP-g-MA) and maleated EOC (EOC-g-MA) prepared by twin-screw extrusion. The X-ray diffraction results in conjuction with transmission electron microscopy images indicated the mixture of exfoliated and intercalated structures possessed by the nanocomposite prepared by simultaneous addition of the ingredients. The nanocomposite in which clay was first mixed with PP and EOC-g-MA and then with EOC and PP-g-MA showed the same morphology. However, in the nanocomposite when clay was first mixed with PP and PP-g-MA and then mixed with EOC and EOC-g-MA, an intercalated structure was observed. The results of mechanical testing showed that there was no significant difference in the yield strength, tensile modulus and flexural modulus among the three nanocomposites. However, the Charpy impact strength of the nanocomposite prepared by simultaneous addition of ingredients was higher than that of the nanocomposites prepared in two mixing steps because of the presence of more organoclay inside the EOC phase in the former.

Highlights

Nowadays, the blending of polypropylene (PP) with a rubbery phase such as ethylene-octene coplymer (EOC) is a common way to improve its impact strength [1,2,3]
In mixture P2 the (001) peak of the clay moves to a lower angle with respect to the organoclay while maintaining a relatively high peak intensity, revealing an intercalated structure. Comparing this figure with the X-ray diffraction (XRD) results of our previous research [12] shows this peak is similar to the peak observed in PP/EOC/PP-g-MA/clay nanocomposite where clay is located in PP phase, which suggests that most of the clay could be located in the PP phase as an intercalated structure in P2 too
The ternary nanocomposites of PP/EOC/clay with double compatibilizers of PP-g-MA and EOC-g-MA were prepared in three blending sequences

Summary

Introduction

The blending of polypropylene (PP) with a rubbery phase such as ethylene-octene coplymer (EOC) is a common way to improve its impact strength [1,2,3]. The method of adding the constituents of polymer blend/clay nanocomposites to the extruder has a strong effect on the dispersion of clay and the microstructure of the nanocomposites [7,10]. The simplest protocol is the simultaneous addition of all components into the extruder at a temperature above the melting temperatures of both polymeric constituents. In this case if the disparity between the melting temperatures of the components is significant, clay is preferentially located in the phase that melts first. As the clay is added to both melted polymer components, clay is not in contact with any solid polymers in this case [10]. Another procedure consisted of adding clay into one polymer and incorporating the polymer [7,10]

Objectives

Results

Conclusion