Crystallization kinetics and crystallization behavior of syndiotactic polystyrene/clay nanocomposites

Self Cite

The polymerizable cationic surfactant, vinylbenzyldimethylethanolammouium chloride (VBDEAC), was synthesized to functionalize montmorillonite (MMT) clay and used to prepare exfoliated polystyrene-clay nanocomposites. The organophilic MMT was prepared by Na(+) exchanged montmorillonite and ammonium cations of the VBDEAC in an aqueous medium. Polystyrene-clay nanocomposites were prepared by free-radical polymerization of the styrene containing intercalated organophilic MMT. Dispersion of the intercalated montmorillonite in the polystyrene matrix determined by X-ray diffraction reveals that the basal spacing is higher than 17.6 nm. These nanocomposites were characterized by differential scanning calorimetry (DSC), transmission electron micrograph (TEM), thermal gravimetric analysis (TGA), and mechanical properties. The exfoliated nanocomposites have higher thermal stability and better mechanical properties than the pure polystyrene. (C) 2002 Wiley Periodicals, Inc

Section: Polystyrene-clay Nonocompositesmentioning

confidence: 99%

Preparation and characterization of polystyrene–clay nanocomposites by free‐radical polymerization

Tseng

Lee

et al. 2002

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“…Several techniques for the production of sPSbased nanocomposites have been reported, [2][3][4][5][6]8 but the melt intercalation and solvent intercalation techniques seemed the most promising and therefore were used to synthesize the materials analyzed in the present study.…”

Section: Introductionmentioning

confidence: 99%

“…2 Syndiotactic polystyrene (sPS) is a very promising engineering polymer. It is synthesized with a specific metallocene catalyst, which enables a merely 100% stereo-regular conformation (having the phenyl rings regularly alternated from side to side with respect to the polymer chain backbone) 3 to be achieved. This opens the possibility of obtaining a semicrystalline arrangement.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of sPS/montmorillonite nanocomposites

Torre

Lelli

Kenny

2006

ABSTRACT:The present work analyzed the possibility of obtaining and producing syndiotactic polystyrene (sPS)-based nanocomposites. The work first focused on possible technology to use for intercalation from solution and melt intercalation. Using a blend of sPS with atactic polystyrene (aPS) as the matrix was also considered. Thermal analysis techniques, such as differential scanning calorimetry (DSC) and thermogravimetry (TGA), were used to study the thermal properties and stability of the nanocomposites obtained and to select the most appropriate nanocharges. The effect of the introduction of nanofillers on these properties also was evaluated. X-ray diffraction was used to investigate the degree of clay exfoliation. Finally, mechanical characterization of the nanocomposites obtained was performed and compared to that of the pure material. The tests demonstrated that nanodispersion of phyllosilicate layers improved the mechanical behavior of the polymers analyzed, especially the annealed sPS.

“…10 The crystallization of PA6 is often influenced not only by processing conditions, but also by the presence of the reinforcing phase (PAM), which generally favors heterogeneous nucleation by acting as nucleation sites for crystallization. 11,12 As PA6 is a semicrystalline polymer and its mechanical and thermal properties are strongly dependent on the processing conditions, analysis of the isothermal and nonisothermal crystallization kinetics of PA6 and PAM/PA6 composites is carried by DSC in this article.…”

Section: Introductionmentioning

confidence: 99%

Isothermal and nonisothermal crystallization kinetics of MC nylon and polyazomethine/MC nylon composites

Ding

et al. 2004

Crystallization kinetics of MC nylon (PA6) and polyazomethine (PAM)/MC nylon (PAM/PA6) both have been isothermally and nonisothermally investigated by different scanning calorimetry (DSC). Two stages of crystallization are observed, including primary crystallization and secondary crystallization. The Avrami equation and Mo's modified method can describe the primary stage of isothermal and nonisothermal crystallization of PA6 and PAM/ PA6 composite, respectively. In the isothermal crystallization process, the values of the Avrami exponent are obtained, which range from 1.70 to 3.28, indicating an average contribution of simultaneous occurrence of various types of nucleation and growth of crystallization. The equilibrium melting point of PA6 is enhanced with the addition of a small amount of rigid rod polymer chains (PAM). In the nonisothermal crystallization process, we obtain a convenient method to analyze the nonisothermal crystallization kinetics of PA6 and PAM/PA6 composites by using Mo's method combined with the Avrami and Ozawa equations. In the meanwhile, the activation energies are determined to be -306.62 and -414.81 KJ/mol for PA6 and PAM/PA6 (5 wt %) composite in nonisothermal crystallization process from the Kissinger method. Analyzing the crystallization halftime of isothermal and nonisothermal conditions, the over rate of crystallization is increased significantly in samples with a small content of PAM, which seems to result from the increased nucleation density due to the presence of PAM rigid rod chain polymer.