Poly(p-phenylene terephthalamide) (PPTA) is mostly
used as a low-density polymeric fiber with high specific stiffness,
strength, and thermal and chemical stability. The fiber is used as
a reinforcement in composite materials in the aerospace and automobile
industries, as well as in ballistic and stab-resistant articles. However,
its use in composite materials is hampered by its low interfacial
affinity with polymeric matrices due to its smooth and inert surface.
To overcome such low interfacial interaction, various treatments have
been applied to modify the aramid surface. However, it is still challenging
to identify an industrially feasible process that does not negatively
impact mechanical properties of the aramid fibers. The objective of
this study was to investigate different ionic liquids (ILs) with suitable
chemical structures as alternative compatibilizers for aramid fibers
and epoxy resin. Kevlar fibers were treated with ethanolic solutions
of imidazolium IL (1-n-butyl-3-methylimidazolium
chloride, 1-carboxymethyl-3-methylimidazolium chloride, 1-triethyleneglycol
monomethyl ether-3-methylimidazolium methanesulfonate, or 1-n-butyl-3-methylimidazolium methanesulfonate) and then analyzed
by infrared spectroscopy, thermogravimetry, scanning electron microscopy,
and X-ray photoelectron spectroscopy. Fiber tensile tests, pull-out
tests, and contact angle measurements were used to characterize the
fiber and its interface with the epoxy resin. Treatment with all IL,
except 1-carboxymethyl-3-methylimidazolium chloride, enhanced the
wettability and adhesion of the fibers without imparing mechanical
properties. Epoxy resin-based composites were produced using commercial
fabrics before and after 1-triethyleneglycol monomethyl ether-3-methylimidazolium
methanesulfonate treatment and characterized via tensile and short-beam
tests. The composite produced with treated fabrics presented slightly
higher tensile strength, modulus, and interfacial shear strength.
This improvement can be of
interest to the composite sector.