Preparation of a long-alkyl-chain silane grafted organic montmorillonite and its nanocomposite with SEBS

Abstract

In this study, a modified montmorillonite (W-H-OMMT) was prepared by intercalating pristine montmorillonite using a phosphorus salt and a subsequent grafting using a long-alkyl-chain silane, and the nanocomposites with poly[styrene-(ethylene-co-butylene)-styrene] (SEBS) were prepared by melt blending. The pristine and the modified MMT were characterized by XRD, FT-IR, XPS and SEM. The morphology of the SEBS nanocomposites was studied using XRD, SEM and TEM, and the results can be correlated well with transparency, color, surface contact angle, rheological behavior, thermal and mechanical properties of the nanocomposites. As compared with pristine and the modified clay, more uniform dispersion and improved compatibility are observed for the W-H-OMMT in the SEBS matrix, resulting in better transparency and more hydrophobic surface for the SEBS/W-H-OMMT nanocomposite. Better thermal stability, a synergetic effect in tensile strength and elongation at break were observed, which can be attributed to well dispersion of the W-H-OMMT, as well as perfect adhesion between the W-H-OMMT and the SEBS matrix from the enhanced molecular interaction between the long-alkyl chain and the SEBS molecules. Compared to pure SEBS, the strength and elongation of SEBS/W-H-OMMT nanocomposite increased by 8.5 and 7.6 %; meanwhile, the water contact angel and the 50 % weight loss temperature increased by 5.3 and 13.1 %, respectively. Appropriate silane grafted organic montmorillonite provided an efficient way for the overall performance improvement of SEBS.

Synergistic effect of organophosphate functionalized montmorillonite on properties and water resistance of intumescent flame‐retarded SEBS

“…The degradation process of the SEBS/IFR composites had two steps. Based on our previous study, the mass loss step at temperatures between 200°C and 330°C was attributed to degradation of oil while that above 400°C to degradation of SEBS, respectively . The initial mass loss temperature for the SEBS/IFR/BMMT was slightly higher than those for the SEBS/IFR and SEBS/IFR/HMMT.…”

Effect of injection molding on structure and properties of poly(styrene‐ethylene‐butylene‐styrene) and its nanocomposite with functionalized montmorillonite

“…It seems that the FMMT has strengthened the network structure in the SEBS‐hotpressed, assumed due to additional attractive interaction (e.g., entanglements) between the soft PEB segments in SEBS and long alky chain of the silane molecules that were grafted to the FMMT. [ 25 ] The little influence of FMMT on γc of injection‐molded SEBS would be due to its already strong network structure. Based on the results of the strain sweep, the constant strain was set to 0.2% (in the linear viscoelastic range), and the frequency dependence of G′ and G″ was measured, as shown in Figure 7.…”

“…It is worth discussing the role of FMMT in the SEBS/FMMT nanocomposites. In our previous study, [ 25 ] FMMT was prepared by a two‐step modification, and the interlayer spacing of the MMT remains the same after the second HTDMS silane treatment step. We believe that HTDMS mainly reacts with hydroxyl groups on surface of MMT and grafts onto it.…”

“…The FMMT acts as a reinforcing nanofiller to the SEBS, as is clearly seen from the improved mechanical properties of the hot‐pressed SEBS/FMMT. The long alkyl silane chains on surface of the FMMT was assumed [ 25 ] to entangle with the soft segments of SEBS and form a flexible interface, which is conducive to stress transfer for increasing the tensile strength and the elongation at break of the nanocomposite. The results in this study also support the view above.…”

“…[ 21 ] In our previous research, a long alkyl quaternary phosphorus cationic surfactant with better thermal stability was used to insert MMT, [ 22–24 ] and further a long alkyl chain silane was grafted to prepare functional montmorillonite (FMMT), showing a synergistic strengthening and toughening effect on SEBS. [ 25 ]…”