Thermoplastic elastomeric nanocomposites from poly[styrene–(ethylene‐co‐butylene)–styrene] triblock copolymer and clay: Preparation and characterization

Abstract

Thermoplastic elastomer (TPE)-clay nanocomposites based on poly[styrene-(ethylene-co-butylene)-styrene] triblock copolymer (SEBS) were prepared. Natural sodium montmorillonite (MMT) clay was organically modified by octadecyl amine to produce an amine-modified hydrophobic nanoclay (OC). Commercially available Cloisite 20A (CL20) and Cloisite 10A, tallow ammine modified nanoclays, were also used. The intergallery spacing of MMT increased on amine modification as suggested by the shifting of the X-ray diffraction (XRD) peak from 7.6 to 4.5 and 3.8°in the cases of OC and CL20, respectively. The latter demonstrated no XRD peak when it was used at 2 and 4 parts phr in the SEBS system. Transmission electron microscopy studies showed the intercalation-exfoliation morphology in SEBS containing 4 parts of CL20 4 -SEBS, agglomeration in SEBS having 4 parts of MMT, and mixed morphology in SEBS with 4 parts of OC systems. Locations of the clay particles were indicated by the atomic force micrographs.Mechanical and dynamic mechanical thermal analysis studies confirmed the best properties with the CL20 4 -SEBS nanocomposites. Significant improvements in mechanical properties such as tensile strength, modulus, work to break, and elongation at break were achieved with the CL20 4 -SEBS in polymer-layered silicate nanocomposites. Dynamic mechanical studies further showed the affinity of the organoclays toward both segments of the TPE and a compatibilization effect with CL20 at a 4-phr loading. Atomic force microscopy showed distinctly different morphologies in nanocomposites prepared through solution and melt processing. Comparisons of the mechanical, dynamic mechanical, and morphological properties of the nanocomposites prepared by melt and solution intercalation processes were done.

Structure-property relationship of specialty elastomer-clay nanocomposites

“…Nanofillers: unmodified sodium montmorillonite clay (MMT) and organically modified (Na + cation-exchanged by long chain quaternary ammonium ion) clay (Sadhu and Bhowmick 2004;Ganguly et al 2006;Maiti and Bhowmick 2006a) and Cloisite 20A (CL) were procured from Southern Clay Products, TX, USA.…”

“…1-5 wt%) (Usuki et al 1993;Giannelis et al 1999;Krishnamoorti et al 2001;Pinnavaia and Beall 2001;Roy and Okamoto 2003). From our laboratory, we have reported a number of polymer nanocomposites with unique properties (Pramanik et al 2003;Sadhu and Bhowmick 2003;Bandyopadhyay et al 2004;Bhowmick 2004, 2005;Sengupta et al 2005;Ganguly et al 2006Ganguly et al , 2007Maiti and Bhowmick 2006a, b, c). In this study, unmodified (MMT) and organically modified (CL) montmorillonite nanoclays having a 2 : 1 tetrahedraloctahedral layer structure (TOT), high aspect ratio, high cation-exchange capacity and self-assembling behaviour via specific interactions to form a stacked arrangement have been chosen to prepare fluoroelastomer and block copolymer [poly (styrene-b-ethylene-co-butylene-b-styrene (SEBS)] based nanocomposites.…”

“…Fluroelastomer was dissolved in methyl ethyl ketone (20 wt% solution) while SEBS was dissolved in toluene. Dispersed nanoclay was then added to respective elastomer solution as per the procedures described in our earlier publications Bhowmick 2003, 2004;Ganguly et al 2006;Maiti and Bhowmick 2006a). After stirring for 2 h, nanocomposite solution was cast on levelled glass plate and dried slowly for 2 days.…”

“…In the second part of study, the phase detected images in the tapping mode atomic force microscopy exhibited a well-ordered phase separated morphology ( Very stiff nature of the clay particles in the matrix has been analysed from the almost zero pull-off and snap-in force in the force-distance analyses of SEBS based nanocomposite in single point-and force-volume modes by AFM force study (force-deflection curves were recorded by plotting the cantilever deflection against movement of piezo in z-direction) following the Hook's law (F = k. Z) (Ganguly et al 2006(Ganguly et al , 2007Maiti and Bhowmick 2006b).…”

Interfacial treatment effects on behavior of soft nano-composites for highly stretchable dielectrics

“…In our case, the interaction between SEBS and TiO2 is obstructed by the non-polar nature of SEBS, which prevents the polar inorganic TiO2 particles form properly dispersing throughout the polymer matrix uniformly. To resolve this issue Ganguly et al [19] proposed modifying the SEBS by grafting polar functional groups such as maleic anhydride, improving the dispersion process.…”