Conductive
aramid (PPTA) fibers are highly needed for making flexible
conductive materials, antistatic materials, and electromagnetic shielding
materials. In this work, silver-plated conductive PPTA fibers with
high conductivity and excellent mechanical properties were prepared
by the electroless plating of PPTA fibers modified with crosslinked
hyperbranched polyamide-amine (HPAMAM). The crosslinked HPAMAM creates
a stable interface between the PPTA fibers and the silver plating.
The morphology and physicochemical properties of the modified and
the silver-plated fibers were characterized by Fourier transform infrared
spectroscopy, scanning electron microscopy, atomic force microscopy,
X-ray diffraction, X-ray photoelectron spectroscopy, and thermogravimetric
analysis. Three epoxy crosslinking agents with different chain lengths
were used to crosslink HPAMAM, and the effects of HPAMAM concentration,
crosslinking agent dosage, and crosslinking time on the resistance
of the fibers were studied. The long chain crosslinking agent appears
to be beneficial to silver plating. The lowest resistance (0.067 Ω/cm)
was attained when HPAMAM was modified by diethylene glycol diglycidyl
ether (1:1 molar ratio), and 20 g/L HPAMAM was used to modify the
PPTA fibers. The tensile strength of the original PPTA fibers decreased
by only 3% or less after silver plating.