Enhanced electrical conductivity of polypyrrole/polypyrrole coated short nylon fiber/natural rubber composites prepared by in situ polymerization in latex

In this paper we report the characterization and properties of conductive elastomeric composites of polypyrrole (PPy) and PPy coated short Nylon-6 fiber (F-PPy) based on natural rubber (NR) prepared by in situ polymerization method. PPy/NR blends were prepared by polymerizing pyrrole in NR latex using anhydrous ferric chloride as oxidizing agent, p-toluene sulphonic acid as dopant and vulcastab VL as stabilizer. PPy/F-PPy/NR composites were prepared as above in presence of short nylon fiber. The products were coagulated out, dried, compounded on a two roll mill and moulded. The cure pattern, DC electrical conductivity, morphology, mechanical properties, thermal degradation parameters and microwave characteristics of the resulting composites were studied. Incorporation of PPy to elastomer retards the cure reaction whereas addition of fiber accelerates the cure reaction. DC conductivity up to 6.25 × 10−2 was attained for NR/PPy/F-PPy system. The composites containing F-PPy exhibited better mechanical properties compared to NR/PPy systems. The absolute value of the dielectric permittivity, AC conductivity and absorption coefficient of the conducting composites prepared were found to be much greater than the gum vulcanizate. PPy and F-PPy were found to decrease the dielectric heating coefficient and skin depth significantly.

► PPy/PPy coated fiber/NR composites were prepared by in situ polymerization in latex. ► DC conductivity 6.25 × 10−2 S/cm was attained for the composite. ► PPy declined mechanical properties of NR while PPy coated fiber enhanced. ► The conducting composites exhibited high dielectric permittivity and AC conductivity. ► Skin depth and dielectric heating coefficient of the composites decreased substantially.