Preparation of tough, high modulus, and creep-resistant PS/SIS/halloysite blend nanocomposites

In this work, polystyrene (PS)/poly(styrene-b-isoprene-b-styrene) (SIS)/organophilic halloysite nanotube (Org-HNT) blend nanocomposites were produced by melt compounding technique. The significant improvements in both toughness and impact strength values were obtained in PS/SIS blends containing 20%, 30%, and 40% SIS elastomer as compared to neat PS. Among them, PS-30SIS blend with a co-continuous morphology exhibited moderate tensile and impact properties and its nanocomposites having 3, 5, 7 and 10 phr Org-HNT were prepared through the melt mixing method. All the nanocomposites exhibited continuous/fibrillar morphologies with smaller elastomer domains and higher tensile modulus and toughness as compared to PS-30SIS blend. Among them, the nanocomposite having 7 phr Org-HNT and 30% SIS phase (7H-30SIS) exhibited the highest impact strength with enhanced tensile properties. The same nanocomposite exhibited about 21% and 100% increments in the modulus and toughness in comparison to its blend, respectively. The 7H-30SIS nanocomposite increased storage moduli of PS-30SIS blend at glass transition regions of both polyisoprene and PS phases and also at room temperature. Moreover, the rubbery storage moduli of the nanocomposites were found to be about 37% and 53% higher for 7 and 10 phr Org-HNT loaded nanocomposites, respectively, in comparison with that of PS-30SIS blend. The creep deformation and permanent deformation of the blend both decreased via introduction of the nanotubes which is in agreement with aforementioned improvements in the stiffness.