This paper reviews recent advances in polyamide 6(PA6) nanocomposites with graphene-based fillers including current works using graphite nanoplatelet fillers.Almost all of the latest important publications relating to the preparation, morphology and properties (such as thermal stability, thermal conductivity, electrical conductivity, mechanical property, flame retardant and gas barrier properties) of graphene/PA6 nanocomposites are summarized. An outlook of the current challenges in this field is provided for potential guide progress on the development of graphene/polymer nanocomposites too. Abbreviations: G Graphene GT Graphite GO Graphene oxide FG Functional graphene RGO Reduced graphene oxide EG Exfoliated graphite GTO Graphite oxide GTPS Graphite nanoplatelets GIC Graphene intercalation compounds FGT Flake graphite EGTPS Exfoliated graphite nanoplatelets LTEGT Low-temperature expandable graphite SG Solar graphene CF Carbon fiber GNS Graphene nanosheets MWNT Multi walled carbon nanotubes SMA Styrene-maleic-anhydride MB Master batch THR Total heat release PHRR Peak heat release rate TSP Total smoke production MLG Multi-layer graphene FLG Few-layer graphene SLG Single-layer graphene 1 *Corresponding authors.

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ABSTRACT:The crystal morphology and nonisothermal crystallization kinetics of short carbon fiber/poly(trimethylene terephthalate) (SCF/PTT) composites were investigated by polarized optical microscopy (POM) and differential scanning calorimetry (DSC). The optical micrographs suggest that the more content of SCF in composites, the smaller size of the spherulites is. Moreover, the addition of SCF can lead to forming banded spherulites in composites. The Avrami equation modified by Jeziorny, Ozawa theory and the method developed by Mo were used, respectively, to fit the primary stage of nonisothermal crystallization of various composites. The results suggest that the SCF served as nucleation agent, accelerates the crystallization rate of the composites, and the more content of SCF, the faster crystallization rate is. Effective activation energy calculated by the differential iso-conversional method developed by Friedman also concludes that the composite with more SCF component has higher crystallization ability than that with less SCF content. The kinetic parameters U * and K g are determined, respectively, by the HoffmanLauritzen theory.

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ABSTRACT:The isothermal crystallization and crystal morphology of poly(trimethylene terephthalate) (PTT)/poly (ethylene 2,6-naphthalate) (PEN) blends were investigated with differential scanning calorimetry and polarized optical microscopy. The commonly used Avrami equation was used to fit the primary stage of isothermal crystallization. The Avrami exponents were evaluated to be in the range of 3.0-3.3 for isothermal crystallization. The subsequent melting endotherms of the blends after isothermal crystallization showed multiple melting peaks. The crystallization activation energies of the blends with 20 or 40% PTT was À48.3 and À60.9 kJ/mol, respectively, as calculated by the Arrhenius formula for the isothermal-crystallization processes.The Hoffman-Lauritzen theory was also employed to fit the process of isothermal crystallization, and the kinetic parameters of the blends with 20 or 40% PTT were determined to be 1.5 Â 10 5 and 1.8 Â 10 5 K 2 , respectively. The spherulite morphology of the six binary blends formed at 1908C showed different sizes and perfect Maltese crosses when the PTT or PEN component was varied, suggesting that the greater the PTT content was, the larger or more perfect the crystallites were that formed in the binary blends.

The melting, crystallization behaviors, and nonisothermal crystallization kinetics of the ternary blends composed of poly(ethylene terephthalate), poly(trimethylene terephthalate) (PTT) and poly(buthylene terephthalate) (PBT) were studied with differential scanning calorimeter (DSC). PBT content in all ternary blends was settled invariably to be one-third, which improved the melt-crystallization temperature of the ternary blends. All of the blend compositions in amorphous state were miscible as evidenced by a single, composition-dependent glass transition temperature (T g ) observed in DSC curves. DSC melting thermograms of different blends showed different multiple melting and crystallization peaks because of their various polymer contents. During melt-crystallization process, three components in blends crystallized simultaneously to form mixed crystals or separated crystals depending upon their content ratio. The Avrami equation modified by Jeziorny and the Ozawa theory were employed to describe the nonisothermal crystallization process of two selected ternary blends. The results spoke that the Avrami equation was successful in describing the nonisothermal crystallization process of the ternary blends. The values of the t 1/2 and the parameters Z c showed that the crystallization rate of the ternary blends with more poly(ethylene terephthalate) content was faster than that with the lesser one at a given cooling rate. The crystal morphology of the five ternary blends investigated by polarized optical microscopy (POM) showed different size and distortional Maltese crosses or light spots when the PTT or poly(ethylene terephthalate) component varied, suggesting that the more the PTT content, the larger crystallites formed in ternary blends.