Preparation of SPS nanocomposites

TEM is a direct way to observe the real dispersion status of the organoclay in the polymer matrix. Differential scanning calorimetry (DSC) and TGA are commonly used to study the thermal properties of polymeric systems, and also, some miscibility and thermal stability information can be deduced from these measurements [7,8]. Rheological properties are also monitored to see the time evolution of the intercalated structure as suggested by Lim and Park (Fig. 20.3) [9]. 

Due to the streoregular structure of SPS, its melting temperature is as high as 270 °C. Typical properties of polymers under consideration and organoclays used in this study are summarized in Table 20.1. 

As suggested in References 10 and 11, to fabricate SPS nanocomposites via melt intercalation is not an easy task. One of the reasons is the thermal instability of the organic materials on the inner surface of the organoclay [12,13]. Lee, Lim, and Park found out that at around 190°C, the alkyl ammonium part is detached from the organoclay so that the gallery spacing is reduced accordingly 

SEBS-MA 72,000 Styrene/ ethylene = 29/71, MA = 2wt % Shell Chem., Los Angeles, CA 

styrene-maleic anhydride random copolymer SEBS-MA, maleic anhydride grafted styrene-ethylene-butylene-styrene block copolymer OPS, poly(styrene-co-vinyloxa2 lin). 

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Figure 20.8 Mechanical properties of SPS nanocomposites prepared by direct melt intercalation method (a) tensile strength, (b) tensile modulus, and (c) flexural modulus. Reprinted with permission from Reference 15. Copyright Wiley-VCH Verlag GmbH Co. KGaA.

Maeda S, Armes SP (1993) Preparation of novel polypyrrole-silica colloidal nanocomposites. J Colloid Interface Sci 159(l) 257-259... 

Schmid A, Armes SP, Leite CAP, Galembeck F (2009) Efficient preparation of polystyrene/silica colloidal nanocomposite particles by emulsion polymerization using a glycerol-functionaUzed sihca sol. Langmuir 25(4) 2486-2494... 

Nanocomposites of syndiotactic polystyrene (sPS) employing MMT-hexadecyltributylphosphonium [40, 41] and high-impact polystyrene (H1PS)/MMT-hexadecyltriphenylphosphonium [42] were prepared by melt-blending and in situ coordination-insertion polymerization. Partially exfoliated or intercalated materials were obtained in all cases, and a decrease of crystallinity of sPS was observed. However, the presence of clay did not have a strong influence on the sPS thermal transitions. Thermal decomposition of the material was slowed and mechanieal properties were improved in the presence of low organoclay content. Intercalated HIPS nanocomposites were obtained, with improved thermal and flame retardant properties compared to pure HIPS (Figure 3.8). 

J. Gurt Santanach, C. Estourn s, A. Weibel, A. Peigney, G. Chevallier and C. Laurent, Sp>ark plasma sintering as a reactive sintering tool for the preparation of surface-tailored Fe-FeA1204-A1203 nanocomposites Scripta Materialia 60(4), (2009), 195-198. 

On the other hand, Bhattacharya et al. have reported the plasticization effect of organically modified layered silicates on dynamic mechanical properties [13]. In this work, nanocomposites of SBR have been prepared using various nanofillers like modified and unmodified montmorillonite, SP, hectorite etc. It has been observed that the Tg shifts to lower temperature in all the nanocomposites, except for systems from hectorite and NA. This is due to the fact that clay layers form capillaries parallel to each other as they become oriented in a particular direction. Due to wall slippage of the unattached polymer through these capillaries, the Tg is lowered, which could be even more in the absence of organo-modifiers [13]. A similar type of plasticization effect is also noted in the case of the low... 

Maeda S, Armes SP (1994) Preparation and characterization of novel polypytrole-silica colloidal nanocomposites. J Mater Chem 4(6) 935-942... 

Percy Ml, Amalvy II, Randall DP, Armes SP, Greaves SJ, Watts IF (2004) Synthesis of vinyl polymer-silica colloidal nanocomposites prepared using commercial alcohohc sdica sols. Langmuir 20(6) 2184-2190... 

Owing to the large aspect ratio of individual day platelets, the performance of nanocomposites is sensitive to the degree of dispersion and, thus, to the preparation method. For example, better performance has been reported for PP-based PNC prepared by the master batch (MB) method than by a single pass (SP) [378]. A similar... 

Abdullayev E, Joshi A, Wei W, Zhao Y, Lvov Y (2012) Enlargement of halloysite clay nanotube lumen by selective etehing of aluminum oxide. ACS Nano 6(8) 7216-7226 Alexandre M, Dubois P (2000) Polymer-layered silicate nanocomposites preparation, properties and uses of a new class of materials. Mater Sci Eng R Rep 28(1-2) 1-63 Aice A, Earle MJ, Katdare SP, Rodriguez H, Seddon KR (2007) Phase equilibria of mixtures of mutually immiscible ionie liquids. Fluid Phase Equilib 261(l-2) 427 33 Azizi Samir MAS, Alloin F, Dufresne A (2005) Review of recent research into cellulosic whiskers, their properties and their application in nanocomposite field. Biomacromolecules 6(2) 612-626... 

Fig. 3.17 Electrical conductivity versus SWCNT weight concentratitm for nanoctnnposites of Poly (Butylene Terephthalate) prepared by direct mixing (DM) and for nanocomposites prepared by in situ polymerization (I-SP). Reprinted with permission from Elsevita- (Hernandez et ai. 2006)...

The preparation and characterization of novel syndiotactic polystyrene/ 44 polyamide-6/sulfonated syndiotactic polystyrene/dodecylamine-modified montmorillonite (SPS/PA6/SSPS/MTA) nanocomposite by a melt-intercalation-blend process... 

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