The dielectric property and percolated behaviour of polymer matrix composites largely depend on the morphology of conductive fillers and external stimulations especially when the composites are processed by melting bl...The dielectric property and percolated behaviour of polymer matrix composites largely depend on the morphology of conductive fillers and external stimulations especially when the composites are processed by melting blending and extrusion-injection way.In this study,the poly(methyl methacrylate)(PMMA)matrix composites incorporated by two kinds of graphene nanoplatelets(GNP),G5 and G150 with different aspect ratios(the ratio of diameter and thickness)are prepared to study the influence of GNP morphology on the dielectric performances close to percolation threshold(f_(c)).After annealing at glass transition temperature(T_(g))for 1 h,the dielectric permittivities of PMMA/G5 and PMMA/G150 near fc increase 43 and 38%,respectively,while the dielectric loss change little.This improvement on the dielectric property is possibly attributed to the slight change of the distance between adjacent GNPs after annealing at T_(g)which enables to arouse stronger polarisation by tunnelling effect.展开更多
Graphite nanoplatelets(GNPs)with their intrinsic two-dimensional structure make an excellent compromise of advantages of both graphite and graphene.Due to their outstanding inherent properties,GNPs have been widely us...Graphite nanoplatelets(GNPs)with their intrinsic two-dimensional structure make an excellent compromise of advantages of both graphite and graphene.Due to their outstanding inherent properties,GNPs have been widely used as the functional fillers to improve certain performances of polymer-based composites.However,the multi-layer stacked construction of GNPs could form aggregations easily,which limits their application in polymer-based dielectric composites.Here,the authors exhibit a polydimethylsilicone(PDMS)-based nanocomposite which loading equivalent carbon nanotubes(CNTs)and GNPs as co-loading fillers,whose dielectric properties are improved significantly.The composites were fabricated through a highly-shearing mechanical mixing process.During the mixing process,both intrinsic CNTs entanglements and GNPs stacked aggregation could be ameliorated due to the interaction between these two types of fillers.Compared with the GNPs solely loaded composites,a small quantity of CNTs addition endows GNPs/CNTs/PDMS ternary composites with a significantly decreased percolation threshold(f_(c)∼1.7 vol.%).Both GNPs and CNTs,these two representative conductive carbon constructions with high aspect ratios are able to effectively enhance the establishing efficiency of internal conductive network inner composites.These results indicate that the development of internal conductive network and dielectric performance of nanocomposites are able to be optimised through the strategy of taking advantage of the synergistic effect of multi-type fillers reasonably.展开更多
文摘The dielectric property and percolated behaviour of polymer matrix composites largely depend on the morphology of conductive fillers and external stimulations especially when the composites are processed by melting blending and extrusion-injection way.In this study,the poly(methyl methacrylate)(PMMA)matrix composites incorporated by two kinds of graphene nanoplatelets(GNP),G5 and G150 with different aspect ratios(the ratio of diameter and thickness)are prepared to study the influence of GNP morphology on the dielectric performances close to percolation threshold(f_(c)).After annealing at glass transition temperature(T_(g))for 1 h,the dielectric permittivities of PMMA/G5 and PMMA/G150 near fc increase 43 and 38%,respectively,while the dielectric loss change little.This improvement on the dielectric property is possibly attributed to the slight change of the distance between adjacent GNPs after annealing at T_(g)which enables to arouse stronger polarisation by tunnelling effect.
文摘Graphite nanoplatelets(GNPs)with their intrinsic two-dimensional structure make an excellent compromise of advantages of both graphite and graphene.Due to their outstanding inherent properties,GNPs have been widely used as the functional fillers to improve certain performances of polymer-based composites.However,the multi-layer stacked construction of GNPs could form aggregations easily,which limits their application in polymer-based dielectric composites.Here,the authors exhibit a polydimethylsilicone(PDMS)-based nanocomposite which loading equivalent carbon nanotubes(CNTs)and GNPs as co-loading fillers,whose dielectric properties are improved significantly.The composites were fabricated through a highly-shearing mechanical mixing process.During the mixing process,both intrinsic CNTs entanglements and GNPs stacked aggregation could be ameliorated due to the interaction between these two types of fillers.Compared with the GNPs solely loaded composites,a small quantity of CNTs addition endows GNPs/CNTs/PDMS ternary composites with a significantly decreased percolation threshold(f_(c)∼1.7 vol.%).Both GNPs and CNTs,these two representative conductive carbon constructions with high aspect ratios are able to effectively enhance the establishing efficiency of internal conductive network inner composites.These results indicate that the development of internal conductive network and dielectric performance of nanocomposites are able to be optimised through the strategy of taking advantage of the synergistic effect of multi-type fillers reasonably.
