Abstract
In order to enhance the interfacial adhesion of poly(p-phenylene terephthalamide) (PPTA) fibers to the rubber composites, a novel method to deposit multi-walled carbon nanotubes (MWCNTs) onto the surface of PPTA fibers has been proposed in this study. This chemical modification was performed through the introduction of epoxy groups by Friedel–Crafts alkylation on the PPTA fibers, the carboxylation of MWCNTs, and the ring-opening reaction between the epoxy groups and the carboxyl groups. The morphologies, chemical structures, and compositions of the surface of PPTA fibers were characterized by scanning electron microscope, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The results showed that MWCNTs were uniformly deposited onto the surface of PPTA fibers with the covalent bonds. The measurement of contact angles of the fibers with polar solvent and non-polar solvent indicated that the surface energy of deposited fibers significantly increased by 41.9% compared with the untreated fibers. An electronic tensile tester of single-filament and a universal testing machine were utilized to measure the strength change of the fibers after modification and the interfacial adhesion between the fibers and the rubber matrix, respectively. The results showed that the tensile strength had not been obviously reduced, and the pull-out force and peeling strength of the fibers to the rubber increased by 46.3% and 56.5%, respectively.
Highlights
As a kind of artificial organic fiber, poly(p-phenylene terephthalamide) (PPTA) fiber has good integrated performances including high specific strength and elastic modulus as well as great heat resistance, corrosion properties, and toughness [1,2,3]
The reason for preparation of multi-walled carbon nanotubes (MWCNTs) suspension was that MWCNTs could be efficiently
MWCNTs could be alkylation of PPTA fibers, the epoxy groups could be grafted at multipoints on the benzeneefficiently rings by dispersed in the
Summary
As a kind of artificial organic fiber, poly(p-phenylene terephthalamide) (PPTA) fiber has good integrated performances including high specific strength and elastic modulus as well as great heat resistance, corrosion properties, and toughness [1,2,3]. Chemical modification methods including acid etching [14,15], biological enzyme [16,17], and surface grafting [18,19] can introduce active groups onto the surface of fibers or destroy the crystal states. In Chen and co-workers’ research [24], the acyl chloride-functionalized MWCNTs were chemically deposited onto aramid fibers to introduce the amino groups, which increased the single-filament tensile strength and interlaminar shear strength by. Grafted the oxidized MWCNTs onto the glass fiber by ring-opening reaction of epoxy groups in order to improve various properties of the composites. With the effects of ultrasonic and basic catalyst, the carboxylated MWCNTs suspended in NMP could form covalent bonds with PPTA (namely, the epoxy ring-opening reaction) to achieve chemical deposition. The interfacial adhesive performance of PPTA fibers with the rubber matrix was characterized by pull-out test and peeling strength test performed by universal testing machine
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