Dependence of Electrical Conductivities of Carbon Black Filled Nylon-12 Fibers on Spinning Conditions

Abstract

Spinning conditions for undrawn carbon black (CB) filled nylon 12 (Ny12) fibers were studied to get electro-conductive fibers with well developed conduction routes of CB. The electrical conductivities of such fibers are assumed to be excellent and less dependent on the circumstance where they are used. Spinning was carried out using a spinneret equipped with a cooling chamber or a heating chamber. Acetylene black (AB) was employed as CB. The average volume resistivity (resistivity) for the fibers tended to decrease with increasing winding speed of the fibers irrespective of the chamber used. The orientation of Ny12 along the fiber axis is considered to be responsible for the lowering of the resistivity. This is because the former increased with increase of the winding speed and it is reasonably assumed that the conduction routes by AB are developed along the fiber axis with the orientation of the matrix polymer. Higher degrees of orientation were achieved for the fibers obtained using the cooling chamber than those using the heating chamber, when the winding speed was kept constant. However, the former had higher resistivity than the latter, when they are compared for the fibers with a same degree of orientation. This was attributed to the variation of a degree of crystallinity. Based on these results, the fibers with AB conduction routes developed effectively and accordingly with lower resistivity could be prepared by choosing proper spinning conditions. The resistivity of the fibers thus obtained remained almost unchanged regardless of the drastic change of relative humidity of the circumstance where they were put, which indicates that they have stable electrical conductivities.