•Aramid fiber surface was modified by PIVPGP of AA to improve wettability, adhesion.•Surface modification effect by PIVPGP of AA increased and then decreased with time.•Surface modification effect ...increased and then stayed unaltered with output power.•Ar plasma was the most effective in PIVPGP of AA on aramid fiber surface.•In studied range, optimum technology of PIVPGP of AA: Ar plasma, 15min, 300W.
Plasma induced vapor phase graft polymerization (PIVPGP) method was applied to modify aramid fiber surface. In this study, aramid fibers were pretreated under various plasma conditions such as different treatment times, output powers and working gases to see how these plasma processing parameters influenced the PIVPGP of acrylic acid (AA) on aramid fiber surface and its surface structure and properties. The analysis results of atomic force microscope (AFM) and X-ray photoelectron spectroscope (XPS) showed the increase of surface roughness and the introduction of OCOH, which confirmed that the PIVPGP of AA on aramid fiber surface was achieved. The contact angle and interfacial shear strength (IFSS) of the aramid fibers modified by PIVPGP of AA prominently decreased and increased, respectively, indicating the obvious improvements of surface wettability and adhesion between aramid fiber and matrix. The surface modification effects of aramid fiber by PIVPGP of AA firstly increased and then after 15min slightly decreased with the increasing plasma treatment time, and but firstly increased and then after 300W nearly remained unchanged with the increasing output power, respectively. Among different working gases, Ar plasma occupied first place, O2 plasma and N2 plasma came second and third in the aspect of PIVPGP of AA on aramid fiber surface, respectively. It could be concluded that the PIVPGP of AA on aramid fiber surface could effectively improve surface wettability and adhesion. Plasma conditions had signally influence on the efficiency of PIVPGP of AA on aramid fiber surface and its surface structure and properties with the primary sequence of plasma treatment time, output power and working gas. Therefore adequate plasma processing parameters should be carefully selected for the optimum surface modification of aramid fiber by PIVPGP of AA.
This work reveals the synergistic effect of argon/nitrogen double plasma alteration on the mechanical properties of para‐aramid fiber/epoxy resin composites with various laminating sequences. ...Acoustic emission monitored interface failure during tensile, bending and fracture testing. A comparative analysis was conducted on the bending performance of the composites modified by argon/nitrogen double plasma and single plasma. The results showed that the synergistic effect of nitrogen and high‐energy molecule argon optimized the modifying effect of argon/nitrogen double plasma. The optimal modification parameters obtained through fiber extraction testing analysis are power 200 W, time 120 s, and Ar/N2 double gas flow rate of 12 sccm. After plasma treatment, twill weave modifies better than plain weave. The AE signal amplitude of PX1 is minimized during stretching. Due to the difference in internal bending stiffness of PX2, interface delamination failure is more likely to occur. The PX5 had greater fiber and matrix debonding failure between mode‐II fracture tests due to the weak modification effect of plain weave and its difficulty in deformation. In ballistic testing, PX1 blocks impact force through fiber bundle stretching deformation, while PX4 is more brittle.
Highlights
Prepare para‐aramid/epoxy resin composites with various laminating sequences.
Study on the interfacial properties of composites treated with double plasma.
The composites with different gas sources treatment were analyzed.
Acoustic emission analysis was used to identify interface failure modes.
The bonding strength between plain and plain interfaces is the lowest.
The influence of argon/nitrogen double plasma on the interface properties of hybrid laminated para‐aramid composites was compared. The failure mode under load and discuss the relationships between various parameters was identified.
•Aramid fibers modification sizing synthesized by sol–gel in the absence of water.•The strength and interfacial adhesion property of modified fibers were improved.•Modified fibers show a special ...surface structure.•The mechanism explains the function of structure.
Aramid fibers were modified through solution dip-coating and interfacial in situ polymerization using a newly synthesized SiO2/shape memory polyurethane (SiO2/SMPU) hybrid. Fourier transform infrared and X-ray photoelectron spectroscopy indicated that the synthesized SiO2/SMPU hybrid successfully coated the fiber surface. The surface morphology of the aramid fibers and the single fiber tensile strength and interfacial shear strength (IFSS) of the composites were determined. The IFSS of the fiber coated with the hybrid improved by 45%, which benefited from a special “pizza-like” structure on the fiber surface.
As a typical kind of high‐performance fibers, heterocyclic aramid fibers are widely used to reinforce resins to prepare advanced lightweight composites with high mechanical performances. However, ...their poor interfacial shear strength limits the combination with resins and leads to undesirable interfacial strength of composites. Thus, heterocyclic aramid fibers with high interfacial shear strength and high tensile strength are highly desired. Herein, heterocyclic aramid fibers with a high interfacial shear strength of 40.04 ± 2.41 MPa and a high tensile strength of 5.08 ± 0.24 GPa are reported, in which the nitrile‐modified poly‐(benzimidazole‐terephthalamide) polymer chains are crosslinked by azide‐functionalized graphene oxide nanosheets. The improved interchain interaction can conquer the splitting of nanofibrils and strengthen the skin‐core layer of heterocyclic aramid fibers, while the graphene oxide can induce an ordered arrangement of polymer chains to improve the crystallinity and orientation degree of fibers. These two effects account for the high interfacial shear strength and high tensile strength of heterocyclic aramid fibers. These findings have provided a strategy to efficiently enhance the interfacial shear strength as well as the tensile strength of high‐performance fibers.
The small addition of GO‐N3 can not only improve the interchain interaction to conquer the splitting of nanofibrils and strengthen the skin‐core layer of fibers, but also improve the crystallinity and orientation degree of GO‐N3/PBIA‐CN fibers, leading to the preparation of GO‐N3/PBIA‐CN fibers with high interfacial shear strength and high tensile strength.
In this study, the impact of incorporating graphene oxide (GO) nanoparticles into the matrix of aramid fiber reinforced polymer (AFRP) composites was investigated. The GO nanoparticles were dispersed ...in the AFRP matrix at three different weight percentages: 0.1%, 0.3%, and 0.5%. The fabrication of the GO dispersed AFRP nanocomposites was achieved using the vacuum assisted resin infusion molding (VARIM) method, and the AFRP plates were cut using a water jet. The sectioned specimens of the fabricated nanocomposites were subjected to low velocity impact tests. The effects of introducing GO nanoparticles at different percentages were evaluated by analyzing the contact force, deflection, maximum absorbed energy versus time and contact force versus deflection curves. Finally, the key parameters of low velocity impact, including contact force, deflection, and maximum absorbed energy, were compared for the different fabricated AFRP nanocomposites. Based on the results, the AFRP composite with 0.3 wt.% of GO nanoparticles exhibited the best performance under low velocity impact loading conditions. However, the agglomeration of nanoparticles became a significant challenge when higher percentages of GO nanoparticles were added to the composite structure. The findings highlight the importance of determining the optimal percentage of nano materials for incorporation into composite structures.
The schematic of VARIM method.
The corrosion resistance of FRP-reinforced ordinary concrete members under the combined action of harsh environments (i.e., alkaline or acidic solutions, salt solutions) and freeze-thaw cycles is ...still unclear. To study the mechanical and apparent deterioration of carbon/basalt/glass/aramid fiber cloth reinforced concrete under chemical and freeze-thaw coupling. Plain concrete blocks and FRP-bonded concrete blocks were fabricated. The tensile properties of the FRP sheet and epoxy resin sheet before and after chemical freezing, the compressive strength of the FRP reinforced test block, and the bending capacity of the prismatic test block pasted with FRP on the prefabricated crack side were tested. The deterioration mechanism of the test block was analyzed through the change of surface photos. Based on the experimental data, the Lam-Teng constitutive model of concrete reinforced by alkali-freeze coupling FRP is modified. The results indicate that, in terms of apparent properties, with the increase in the duration of chemical freeze-thaw erosion, the surface of epoxy resin sheets exhibits an increase in pores, along with the emergence of small cracks and wrinkles. The texture of FRP sheets becomes blurred, and cracks and wrinkles appear on the surface. In terms of failure modes, as the number of chemical coupling erosion cycles increases, the location of failure in epoxy resin sheets becomes uncertain, and the failure plane tilts towards the direction of the applied load. The failure mode of FRP sheets remains unchanged. However, the bonding strength between FRP sheets and concrete decreases, resulting in a weakened reinforcement effect. In terms of mechanical properties, FRP sheets undergo the most severe degradation in the coupled environment of acid freeze-thaw cycles. Among them, GFRP experiences the largest degradation in tensile strength, reaching up to 30.17%. In terms of tensile performance, the sheets rank from highest to lowest as follows: CFRP, BFRP, AFRP, and GFRP.As the duration of chemical freeze-coupled erosion increases, the loss rate of compressive strength for specimens bonded with CFRP is the smallest (9.62% in salt freeze-thaw environment), while the loss rate of bearing capacity is higher for specimens reinforced with GFRP (33.8% in acid freeze-thaw environment). In contrast, the loss rate of bearing capacity is lower for specimens reinforced with CFRP (13.6% in salt freeze-thaw environment), but still higher for specimens reinforced with GFRP (25.8% in acid freeze-thaw environment).
Today, aramid fibers are well known as a high‐performance and ideal material for reinforcement purposes in rubber product manufacturing including hoses, tires, cables, and conveyors composites. ...However, surface modification of aramid fiber is necessary to solve poor interfacial adhesion between aramid fibers and the rubber matrix. Accordingly, in the present study, the effect of the surface modification of aramid fibers using atmospheric pressure plasma treatment with different precursors on adhesion to the rubber matrix was investigated. For that, the plasma coating was conducted using argon as the main working gas, and toluene, acetonitrile, tetraethyl orthosilicate (TEOS), and hexamethyldisiloxane (HMDSO) as liquid precursors. The physical–chemical characterization of the layer confirmed the successful deposition of amorphous carbon, amorphous nitride‐carbon, SiO2, and Polydimethylsiloxane (PDMS)‐like coating layers on the surface of aramid fibers by using toluene, acetonitrile, TEOS, and HMDSO as precursors, respectively. Overall, the result showed that the plasma surface modifications with acetonitrile precursor leads to the increase in interfacial adhesion of aramid/rubber composite, while retaining the tensile strength, and flame resistance properties of aramid as original fibers. Notably, the results of this study confirm the potential use of atmospheric pressure plasma for surface modification of aramid yarn to produce functional aramid for use in rubber composites.
Highlights
The plasma‐coated aramid using HMDSO, TEOS, toluene, and acetonitrile precursors was prepared; and its effect on the tensile properties of aramid fiber as well as interfacial adhesion between aramid/rubber composite was investigated.
The positive effect of atmospheric pressure plasma coating using HMDSO precursor on the tensile properties of aramid fiber was revealed.
The positive effect of atmospheric pressure plasma coating using toluene and acetonitrile on the interfacial adhesion between aramid/rubber composite was revealed.
The positive effect of atmospheric pressure plasma coating using TEOS precursor on the flam resistance property of aramid fiber was revealed.
This study provides valuable insights into the effect of the different plasma‐coated organosilicon and hydrocarbon precursors on the interfacial adhesion between aramid/rubber composite.
Improvement in interfacial adhesion of aramid/rubber composite using atmospheric pressure plasma
Three‐dimensional (3D) braided composites have good integrity and high stability, but aramid fiber (AF) has an inert surface and poor interfacial bonding with resin, which affects the mechanical ...properties of aramid 3D braided composites and limits their development. This paper used catechol/pyrogallol polyamine (CA/PGPA) to modify the AF. The effects of different mass fraction ratios of CA/PGPA and different reaction temperatures on the surface properties of AF and the mechanical properties of 3D braided composites were investigated. The results showed that after the CA/PGPA modification, fiber surface oxygen‐containing groups increased, the roughness became more extensive, the fiber strength increased, and the interfacial shear strength increased. When AF‐CAPG‐II‐40°C, the mechanical properties of the 3D braided composites were improved most significantly. Compared with unmodified composites, the bending modulus was increased by 70%, the compression modulus by 124%, and the shear strength by 55.7%. The epoxy resin modification was carried out based on AF‐CAPG‐II‐40°C, and when the mass fraction of aramid nanofiber/graphene nanoparticle (ANF/G) was 0.7 wt%, 3D braided composites exhibited satisfactory mechanical properties. The bending modulus, compression modulus, and shear strength were increased by 15.3%, 23.3%, and 25.7%, respectively, compared with AF‐CAPG‐II‐40°C.
