Effect of Mixing Process and Morphologies on the Electrical Conductivity of PA6/EVA/CB Composites

Abstract

Nylon6 (PA6)/Ethylene-(vinyl acetate) (EVA)/carbon black (CB) composites with different electrical conductivity were prepared in an internal mixer. The factors influencing the electrical conductivity of the ternary composites were investigated, including mixing mode, mixing time and mass ratio of PA6 and EVA, and so on. Among three kinds of PA6=EVA=CB composites, including ones prepared by directly mixing (composites A), EVA and CB were mixed prior to melt-compounding with PA6 (composites B) and PA6 and CB were mixed prior to melt-compounding with EVA (composites C), the mixing time only significantly influenced the electrical conductivity of composites A. Good conductivity of the composites could be realized because the distance between CB particles became closer with the increasing of mixing time. However, the mixing time has no effect on the electrical properties of the composites B and the composites C, due to there were no CB particles migrated phenomenon happened. Scanning electron microscopy (SEM) was used to assess the fracture surface morphologies and the dispersion of the CB particles. The results showed that the dispersion of the CB particles significantly affects the electrical conductivity of the composites. Based on the study of the influence of various mass ratios of EVA and PA6 on the morphologies and electrical properties of PA6=EVA composites filled with 10 phr (parts per hundred resins) CB particles, we suggested that the mass ratio of EVA and PA6 affected the volume resistivity of the ternary composites significantly. In addition, the composites were almost insulation when the mass ratios of EVA and PA6 were 80=20 and 70=30, while the composites became conductivity with the mass ratio of EVA and PA6 higher than 60=40. The PA6=EVA=CB composites which CB particles locate at the interface of EVA and PA6 have the lowest volume resistivity when the mass ratio of two components was 60=40.

Elastomeric composites based on carbon nanomaterials

“…This is because the CB loose aggregates can work as imperfection sites inside the matrices, where cracks may readily start and propagate. For this reason most studies [3,[77][78][79] on polymers/CB composites (except elastomers) focused on improving electrical conductivity rather than mechanical performance. An electrical percolation threshold in general depends mainly on the CB structure and dispersion inside the matrices.…”

Comparison of Three Interfacial Conductive Networks Formed in Carbon Black-Filled PA6/PBT Blends

“…The use of immiscible binary polymer blends as the matrices has been proven to be a good method for tuning the distribution of conductive particles ever since the pioneering work of Sumita et al in 1991 [ 1 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. It is generally recognized that the formation efficiency of the conductive networks increases to a great extent, compared with single polymer as the matrix, when carbon fillers are selectively localized in one continuous polymer phase or at the interface of a cocontinuous-structured polymer blend, according to the double percolation mechanism [ 12 ].…”

“…Apart from cocontinuous-structure, sea-island structure is another typical phase morphology of polymer blends. However, there are considerably less investigations involving the formation of conductive networks via interfacial localization of carbon fillers in sea-island-structured polymer blends [ 18 , 24 , 25 , 28 ] probably because the interface is not continuous throughout the entire blend and the inter-domain distance is usually far larger than the minimum inter-particle distance (10 nm) required in the average inter-particle distance model [ 30 ]. In the previous work by our research group [ 26 , 27 ], we found that CB can form highly-efficient conductive networks in sea-island-structured thermoplastic polyurethane (TPU)/polyamide copolymer (COPA) and nylon-poly(m-xylene adipamide) (MXD6)/poly(ethylene terephthalate) (PET) blends through thermodynamically-driven interfacial localization.…”