Thermal and mechanical properties of syndiotactic polystyrene/organoclay nanocomposites with different microstructures

Abstract

The fabrication of syndiotactic polystyrene (sPS)/organoclay nanocomposite was conducted via a stepwise mixing process with poly(styrene‐co‐vinyloxazolin) (OPS), that is, melt intercalation of OPS into organoclay followed by blending with sPS. The microstructure of nanocomposite mainly depended on the arrangement type of the organic modifier in clay gallery. When organoclays that have a lateral bilayer arrangement were used, an exfoliated structure was obtained, whereas an intercalated structure was obtained when organoclay with a paraffinic monolayer arrangement were used. The thermal and mechanical properties of sPS nanocomposites were investigated in relation to their microstructures. From the thermograms of nonisothermal crystallization and melting, nanocomposites exhibited an enhanced overall crystallization rate but had less reduced crystallinity than a matrix polymer. Clay layers dispersed in a matrix polymer may serve as a nucleating agent and hinder the crystal growth of polymer chains. As a comparison of the two nanocomposites with different microstructures, because of the high degree of dispersion of its clay layer the exfoliated nanocomposite exhibited a faster crystallization rate and a lower degree of crystallinity than the intercalated one. Nanocomposites exhibited higher mechanical properties, such as strength and stiffness, than the matrix polymer as observed in the dynamic mechanical analysis and tensile tests. Exfoliated nanocomposites showed more enhanced mechanical properties than intercalated ones because of the uniformly dispersed clay layers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1685–1693, 2004

Hierarchically Ordered Montmorillonite Block Copolymer Brushes

“…Extensive research has gone into exfoliating silicate tactoids by means of melt mixing, 13,15,16 solvent blending, 17 or in situ polymerization. 4,18 Regardless of method exfoliation is aided by the addition of an organic modifier to make hydrophilic clays more amenable to hydrophobic polymer interactions and to increase interlayer spacing.…”

Graphitic nanofillers in PMMA nanocomposites—An investigation of particle size and dispersion and their influence on nanocomposite properties

“…These materials can show considerable improvements in mechanical properties such as strength, modulus, and toughness with very low weight percent of the plate-like nanofiller. 4,20,[25][26][27] While these clay nanocomposites can exhibit improved thermal and diffusion barrier properties, increased electrical conductivity cannot be achieved. In this respect, graphite is a more attractive alternative to clay due to its moderately high electrical conductivity, in addition to its substantially higher in-plane elastic modu- 18 Epoxy/EG Solution 0-9 N/A 5 1E-03 Xiao et al 22 PS/EG In-situ þ roll mill 0-61 N/A 2.5 6E-02 Li et al 30 GNP/epoxy Solution sonicate 2h 2 À16 N/A sonicate 8h 2 13 Chen et al 31 PS/EG In-situ 0-5 N/A 1.8 2E-06 Du et al 32 POBDS/GNP In-situ 0-15 81 c (15 wt %) 4 2E-02 Weng et al 33 Nylon 6/FG In-situ 0-3.5 N/A 1.5 a 1E-04 Chen et al 34 PS/GNP In-situ 0-16 N/A 1.5 1E-06 PS/UG 0-16 6 8E-05 Cho et al 35 PETI/EG In-situ 1 26 N/A 3 3 3 5 3 9 10 42 Chen et al 14 PMMA/GNP In-situ 0-6 N/A 0.5 3E-05 PMMA/UG 3 3E-05 Chen et al 36 PVC/PMMA/EG In-situ 0-10 N/A 3.5 2E-05 Weng et al 37 Nylon 6/FG In-situ 0-3.5 N/A 1.2 a 1E-05 Chen et al 38 PMMA/EG d In-situ 0-5 N/A 3.0 1E-02 Du et al 39 PANI/GNP In-situ 0-6 N/A 2 33 Yasmin et al 40 Epoxy Table 1.…”

“…19 Thermal properties have been improved by tens of degrees Celsius with the inclusion of low volume fractions of nanoparticles. [19][20][21][22][23][24] Given these multifunctional characteristics as well as improved mechanical properties, polymer nanocomposites have many existing and potential applications in the aerospace, automobile, and electronics industries.…”

Exfoliated syndiotactic polystyrene-graft-poly(methyl methacrylate)/montmorillonite nanocomposite prepared by solvent blending

“…This clay was used to prepare an sPS-g-PMMA/MMT nanocomposite by a solvent-blending method. 2 and a cation exchange capacity of 95 meq 100 g À1 . The polymer a-ph-ch-sPS was prepared in our laboratory.…”

“…Organic-inorganic hybrids based on layered inorganic compounds, such as clays and organic polymers, have been studied because of their exceptional properties, such as increased modulus, strength, reduced gas permeability and enhanced thermal stability. [1][2][3][4][5] The dispersion of the silicate layers in the polymer matrix is improved by replacing the metal cations in the clay (such as sodium MMT; Na + -MMT) with ions bearing an aliphatic chain to compatibilize the silicate. This compatibilization enhances the silicate's interaction with the polymer by enlarging the interlayer, and the compatibilized clay is known as an organoclay.…”