Synthesis and characterization of clay/polyaniline nanofiber hybrids

Nonisothermal crystallization kinetics, morphology, and tensile properties of polyphenylene sulfide/functionalized graphite nanoplatelets composites

Polyphenylene sulfide (PPS)/graphite nanoplates (GNPs) nanocomposites were manufactured by simple melt compounding. The GNPs were first functionalized using synthesized benzimidazolium salt to improve the compatibility with PPS matrix. The functionalized GNPs showed an exfoliated dispersion in PPS matrix, which also could significantly improve the tensile properties of composites. Differential scanning calorimetry was used to investigate the nonisothermal crystallization kinetics of PPS/functionalized GNPs composites. The results showed that the PPS/functionalized GNPs composites always had a higher crystallization peak temperature ( Tc) than pure PPS resin at different cooling rates due to the addition of GNPs. The GNPs could also play the role of heterogeneous nucleating agents to accelerate the crystallization; however, at high content, they could also limit the mobility of PPS macromolecular chains and hinder the crystallization. The Mo equation could be used to analyze the nonisothermal crystallization kinetics, whereas the Ozawa equation was not suitable for the nonisothermal crystallization process. Consistent with a previous analysis, the results also showed that the addition of GNPs could also decrease the crystallization activation energy ( Ec) of PPS resin at low content while increasing the Ec at high content.

Nonisothermal crystallization kinetics of polyphenylene sulfide composites based on organic clay modified by benzimidazolium salt

Polyphenylene sulfide (PPS)/organic clay nanocomposites were prepared by simple melt blending. A synthesized benzimidazolium salt was used to modify the sodium montmorillonite in order to improve the compatibility with the PPS. The nonisothermal crystallization kinetics of PPS/organic clay composites were investigated by differerntial scanning calorimetry(DSC). It was observed that the crystallization peak temperature of PPS/organic clay composites was higher than pure PPS at various cooling rates. Several models such as the Ozawa and Mo equation were used to characterize the nonisothermal cooling crystallization kinetics of the PPS/organic clay composites. The results indicated that the Ozawa equation was not successful, while the Mo equation was successful to describe the nanoisothermal ctystallization kinetics of PPS/organic clay nanocomposites. The results also indicated that organic clay not only served as heterogeneous nucleating agents for PPS crystallization at lower content but also restricted the mobility and diffusion of PPS chains at higher content. These results were further supported by the crystallization activation energy of the samples determined by the Kissinger method.

Modification of montmorillonite by different surfactants and its use for the preparation of polyphenylene sulfide nanocomposites

Polyphenylene sulfide (PPS)/clay composites were prepared by simple melt blending. Three different kinds of surfactants such as cetyltrimethyl ammonium bromide (CTAB), sodium dodecyl benzene sulfonate (SDBS), and synthetic 1,3-dihexadecyl-3H-benzimidazolium bromide (Bz) were used as organic modifiers for the organic modification process. The benzimidazolium-modified montmorillonite (Bz-MMT) and CTAB-modified MMT (CTAB-MMT) exhibited larger interlayer spacing than SDBS-modified MMT (SDBS-MMT), while SDBS-MMT and Bz-MMT exhibited higher thermal stability compared with the CTAB-MMT. The morphology of the PPS/organic MMT nanocomposites was evaluated by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The nanocomposites based on SDBS-MMT and Bz-MMT exhibited good overall dispersion of organic MMT with a mixed dispersion of intercalated and exfoliated structures. Differential scanning calorimetry and thermogravimetric analysis (TGA) were used to evaluate the thermal properties of PPS/organic MMT nanocomposites. The crystallization process of PPS in all nanocomposites was accelerated, and the crystallinity also increased, when compared with the pure PPS from the DSC analysis. The TGA analysis indicated that nanocomposites based on SDBS-MMT and Bz-MMT exhibited higher thermal stability than composites based on CTAB-MMT due to the well-dispersed nanoplatelets.

Graphene oxide based smart fluids

Graphene oxide (GO), a graphene-related material containing oxygen-functional groups, has attracted considerable attention because of its strongly hydrophilic behavior and potential use in GO-hybrid composites. We put our focus on the fabrication and rheological characteristics of GO-based electrorheological and magnetorheological smart fluids under electric and magnetic fields, respectively in this Highlight. A brief perspective on the significant role of GO in tribology and the amphiphilic characteristics of Pickering emulsions are also included.