Study On The Structure And Electric Properties Of Polyamide 6 Blends Filled With Carbon Black

Polymers filled with carbon black (CB) have been extensively studied and used when appropriate conductivity levels are required. One of the recent trends is to reduce the CB content in composites while maintaining a relatively high conductivity at the same time. The selective distribution of CB into one phase or at the interface of polymer blends can bring on electric conductive materials with lower filler content. This can also provide good processing ability and avoid poor mechanical properties in consequence of high CB content. There are several factors affecting the electric conductivity of CB-filled polymer blends and the mechanism of the electric conductivity has not been clear yet. In this dissertation, sseveral sorts of CB-filled nylon6 (PA6) composites were prepared in HAAKE Thermo-mixer. The morphology, conductivity, thermorheology properties and their relationships were studied.The dispersion states of CB particles in polymer blends were characterized by different methods. The results show the same: CB particles distributed predominately in the PA6 phase in PA6/PS/CB, PA6/PAN/CB composites. The results also show that when CB particles located preferentially in one polymer phase, the ternary composites have the highest electric conductivity usually when the amount of the polymer component in which the CB particles distribute is comparatively less than the polymer component in which the CB particles do not distribute. The addition of PAN component can attract a part of CB particles that transfers to the interface of PA6 and PAN. This makes the formation of a better network structure of CB, and the electric conductivity of the composites increases as a consequence.Studies on the linear viscoelastic behavior of PA6/PS/CB blends were carried out. The results show that polymer blends performance a similarity viscoelastic behavior of the original component. The elastic modulus of PA6/PS/CB composites increases as the CB or PS content increases. CB-filled binary polymer blends show more elastic than CB-filled unitary polymer. The studies on the thermorheological properties of CB-filled PA6 composites demonstrate that while the PAN content in PAN/PA6/CB blends rises, the elastic modulus of the blends increases and tan 5 values of the blends decreases as compared with the PA6/CB composites. The presence of PAN particles enhances the mechanical performance of conductive PA6/CB composites at high temperatures.When a small mass of PAN was introduced into PA6/CB composites, micro-phase separation structures and partial miscibility were confirmed by Advanced Rheometric Expansion System, DMA, TEM and DSC tests. A part of CB particles could be attracted by PAN, and transferred to the interface of PA6 and PAN, leading to an increase of electric conductivity.