Nanocomposites of acrylonitrile-butadiene-styrene/montmorillonite/styrene block copolymers: Structural, rheological, mechanical and flammability studies on the effect of organoclays and compatibilizers using statistically designed experiments

Abstract

Previous study with nanocomposites of acrylonitrile-butadiene-styrene copolymer (ABS) and organophylized montmorillonite clays (OMMT) investigated the effect of clay modifiers polarities on their performance. Nevertheless, the literature has shown that the use of compatibilizers plays a key role in the dispersion of OMMT in polymeric matrices. Therefore, in the present work, ABS/OMMT nanocomposites compatibilized with styrenic block copolymers prepared by melt intercalation in a twin-screw extruder was studied. Nanocomposites formulations followed a 22 factorial design having different kinds of Cloisite OMMT (30B and 20A + 30B) and of compatibilizers (SBS and SEBS- g-MA) as independent variables. Structural (X-ray diffraction) and morphological (transmission electron microscopy) analyses of the nanocomposites showed a better clay dispersion, partially exfoliated, for ABS/30B/SBS than the intercalated morphology for ABS/20A30B/SEBS- g-MA. Rheological dynamic shear tests indicated a tendency to the formation of a percolating network structure for the ABS/OMMT/SBS nanocomposites, independently of nanoclay kind. Besides, these materials presented non-dripping effect on flammability tests. ABS/OMMT/SBS nanocomposites show also the best performance in both uniaxial tensile and dynamic shear storage moduli. These results are probably due to improved affinity between components. In conclusion, among the styrene block copolymers, SBS compatibilizer is more effective than SEBS- g-MA to improve the properties of ABS/OMMT-based nanocomposites.