Polymorphic behavior in syndiotactic polystyrene/clay nanocomposites

Abstract

X-ray diffraction methods were used in an investigation of the structural changes in syndiotactic polystyrene (sPS)/clay nanocomposites. sPS/clay was prepared by the intercalation of sPS polymer into layered montmorillonite. Both X-ray diffraction data and transmission electron microscopy micrographs of sPS/clay nanocomposites indicated that most of the swellable silicate layers were exfoliated and randomly dispersed in the sPS matrix. The X-ray diffraction data also showed the presence of polymorphism in the sPS/clay nanocomposites. This polymorphic behavior was strongly dependent on the thermal history of the sPS/clay nanocomposites from the melt and on the content of clay in the sPS/clay nanocomposites. Quenching from the melt induced crystallization into the ␣-crystalline form, and the addition of montmorillonite probably increased heterophase nucleation of the ␣-crystalline form. The effect of the melt crystallization of sPS and sPS/clay nanocomposites at different temperatures on the crystalline phases was also examined.

Synthesis and characterization of sPS/montmorillonite nanocomposites

“…On the other hand, the annealing process favors the formation of crystalline forms within the polymer, as testified by the appearance of secondary peaks (additional information on identification of the characteristic peaks can be found in refs. [21][22][23][24]. Note that the crystalline form corresponding to the peak at 2 ϭ 5.0°-7.5°, which also was present in the neat polymer (but only after the annealing process), was strongly enhanced by the presence of the nanofiller, as the peak was present in the nanocomposite even before the annealing process (and did not seem to depend on the thermal history of the material).…”

EVA/clay nanocomposite by solution blending: Effect of aluminosilicate layers on mechanical and thermal properties

“…; but they are very limited in number, because polymers are to be hydrophilic and sufficiently polar. 9 Organomodified montmorillonite/polymer nanocomposires based on polystyrene, 16 poly(ε-caprolactone), 17 nylon6, 18 polyaniline 19 and Engage rubber 20 etc. have been reported.…”

Structure and crystallization behaviour of syndiotactic polystyrene/layered double hydroxide nanocomposites

“…The FTIR results are in good agreement with the X‐ray diffraction results. It has been reported that the addition of inorganic nanofillers can influence the polymorphism of sPS . For example, carbon nanotubes, hybrid silica spheres and modified layered silicates stabilize the thermodynamically stable β form over the α form .…”

“…But this is not common in the presence of all kinds of nanofillers. It has been shown that some of the organically modified layered silicates favour the formation of the α form . It has also been reported that the existence of a strong interaction between the filler and polymer matrix favours the formation of thermodynamically favoured crystalline forms .…”