Improvement of the dielectric properties of polyvinylidene fluoride/reduced graphene oxide composites via in-situ ball milling assisted extensional flow field

In this work, a new melt blending method under the synergy of in-situ ball milling (ISBM) and extensional flow field are reported. The corresponding equipment and processing mechanism of this new method are introduced in detail. The improvement in the dielectric properties of polyvinylidene fluoride (PVDF)/reduced graphene oxide (rGO)/hollow glass beads (HGBs) composites are experimentally investigated. Benefit from uniform dispersion and reduced shattered rate of HGBs, the effect of ISBM on the rGO is strengthened. The results of SEM, TEM, XRD, and Raman spectra show that HGBs promote the exfoliation and dispersion of rGO in PVDF matrix. The addition of HGBs not only increases the dielectric constant of the composites, but also reduces the dielectric loss. When the content of rGO is 3.5 wt%, the dielectric constant of PVDF/rGO/HGBs (P-RH) composites reaches 132.7, which is 63.2% higher than that of PVDF/rGO (P-R) composites without HGBs. Moreover, the dielectric loss of P-RH composites is 0.3, which is 23.3% lower than that of P-R composites. To sum up, the new processing method is a simple, green and efficient way to enhance the dielectric properties of PVDF/rGO composites by improving the exfoliation and dispersion of rGO in PVDF.