Improving the Mechanical and Surface Properties of Aramid Fiber by Grafting with 1,4-Dichlorobutane under Supercritical Carbon Dioxide

Abstract

The mechanical and surface properties of aramid fiber were simultaneously improved by grafting with 1,4-dichlorobutane in supercritical carbon dioxide (scCO2). 1,4-dichlorobutane was penetrated and reacted with heterocyclic an aromatic polyamide backbone along with supercritical CO2 fluids. The surface roughness and surface energy of the modified aramid fiber—which were measured by scanning electron microscopy (SEM) and the dynamic contact angle (DCA) test, respectively—significantly increased. X-ray diffractometer (XRD) measurements indicated that the crystallinity of the aramid fiber obviously increased after treatment in scCO2 under stretching. A single fiber tensile test showed that the tensile strength of the aramid fiber greatly enhanced after the modification due to its improved crystallinity characteristics. Moreover, the monofilament pull-out tests indicated that the interfacial shear strength (IFSS) test of the aramid fiber/epoxy composite increased by 24.3% from 51.30 to 63.91 MPa after the modification. This research provides a novel method for the simultaneous surface modification and mechanical improvement of aramid fiber properties.

Ballistic performance of synergistically toughened Kevlar/epoxy composite targets reinforced with multiwalled carbon nanotubes/graphene nanofillers

“…Three characteristic peaks are observed and the bands at 284.6 eV correspond to the C C bond, 287.8 eV correspond to amide and carbonyl groups (O═C NH/C═O) in the fiber and the bands at 289.1 eV correspond to the carbonyl (O═C O) group. [30] From the area analysis of the two graphs, the O═C NH/C═O bond contribution has increased from its initial 26.8% to 34.3% and the O═C O group contribution has seen an increase from 12.2% to 15.2%. [31] The contribution of amide and the carbonyl groups for treated fiber is higher than that for untreated fiber.…”

Recent advancement in surface modification of aramid fiber assisted by supercritical carbon dioxide

“…(iv) The various mechanical behavior of KF/epoxy composite with different treatment times. Reprinted from 45,46,52,53 with permission. Copyright, 2014 & 2019 RSC, 2019 MDPI, and 2018 Johns Wiley & Sons.…”

“…However, in the graft polymerization of monomers chains onto a scCO 2 ‐altered object surface for external characteristics enhancement, the fresh layer is not forming at the similar period of treatment; therefore, external characteristics will not deteriorate with time 50,51 . Jia et al 52 effectively grafted 1,4‐Dichlorebutane on aramid fiber under the scCO 2 environment, which improved the IFSS of epoxy/modified fiber from 51.30 to 63.91 MPa. The deconvolution of the C 1s peaks under XPS spectra for modification of AF under scCO 2 indicates effective covalent bonding of CC from 60.37% to 72.43% after modification.…”

“…However, in the graft polymerization of monomers chains onto a scCO 2 -altered object surface for external characteristics enhancement, the fresh layer is not forming at the similar period of treatment; therefore, external characteristics will not deteriorate with time. 50,51 Jia et al 52…”

Interfacial reinforced carbon fiber composites inspired by biological interlocking structure

“…In particular, these raw fibers could be easily peeled off or pulled out from polymer matrix under load, which seriously affects the load transfer from matrix to fiber and thereby impairs mechanical properties of the composites ( Mittal et al., 2018 ; Liu et al., 2020 ; Li et al., 2016 ). Therefore, relatively poor interfacial property is still an open challenge to achieve satisfactory CFRCs with high mechanical properties ( Wu et al., 2018 , 2021 ; Zhang et al., 2020a ; Beggs et al., 2015 ; Jia et al., 2019 ; Chen et al., 2016 ; Ma et al., 2019 ; Zhan et al., 2021 ; Garlof et al., 2016 , 2017 ).…”