The Effect of Phosphoric Acid Functionalization of Para-aramid Fiber on the Mechanical Property of Para-aramid Sheet

Abstract

The mechanical properties of para-aramid sheet (PAS) are mainly dependent on the interfacial property between para-aramid chopped fibers and fibrids. However, the chemical inertness and smooth surface of para-aramid chopped fiber lead to the poor interfacial adhesion between para-aramid chopped fibers and fibrids. In this study, para-aramid chopped fiber was treated by phosphoric acid (PA) solution with different concentration in order to prepare PAS with high mechanical strength. It was shown that PA-treatment can increase the surface roughness and improve the surface oxygen-containing active groups of para-aramid chopped fibers. In addition, there is a critical value of PA-concentration (20%). Proper PA-treatment gives rise to an increased tensile strength of PAS from 2.41 to 3.41 kN/m by an increment of 41.49%. However, excessive PA-treatment results in a dramatic reduction of tensile strength for para-aramid fibers and also for PAS possibly due to the structure destruction of para-aramid fiber. This work shows a simple but highly-efficient approach for improving the mechanical property of PAS via PA-treatment of para-aramid chopped fibers, and simultaneously elaborating the reinforcing effects for high-performance PAS especially through optimizing the interfacial property between para-aramid chopped fibers and fibrids.

Novel epoxy‐based glass fiber reinforced composites containing compatibilized para‐aramid fibers and silanized nanoclay for improved impact strength

“…[35,37,[41][42][43][44] Park et al [45] treated PA fibers with phosphoric acid (10 wt% H 3 PO 4 ) and obtained improvement in interlaminar shear strength (82%) and fracture toughness (71%). Lu et al [46] treated PA fibers with H 3 PO 4 of different concentrations and obtained 41.49% improvement in tensile strength with (20 wt% concentration) treated fibers. Zhang et al [47] modified the surface of PA fibers (5 wt% calcium chloride/ ethanol solution and 20 wt% silane agent) and reported 47.8% improvement in tensile strength.…”

Composite Aramid Membranes with High Strength and pH-Response

“…As shown in Figure 2 b, the stretching vibration peak of N-H at 3319 cm −1 showed a slight shift to a lower wavenumber, which was due to the introduction of more amino groups (-NH 2 ) via the hydrolysis of the amide groups (-HN-CO-). This spectral change can be attributed to the greater degree of hydrogen bonding due to the introduction of hydroxyl groups [ 28 , 29 ]. The absorption peaks of C=O stretching and O−H bending vibration corresponding to the -COOH were at 1652 and 1404 cm −1 , the peak at 1546 cm −1 was C=O bonds of the diketone, and the peak at 1256 cm −1 was the stretching vibrations of C-O were visible [ 15 ].…”

“…The tensile strength of pure ANF membrane was 112.3 MPa, and the tensile strength decreased to 55.7 MPa, when the content of incorporation HANFs was 50 wt%. The decrease could be due to the hydrolysis ofamide bonds under acidic conditions, which destroyed the original regularity and stability of the aramid fibers [ 29 ]. However, the breaking strength of the ANF/HANF membranes was still much higher than that of most reported polymer films, such as Polyethersulfone, Polysulfone, Poly(vinylidene fluoride) and Polyetheretherketones [ 36 , 37 , 38 , 39 ].…”

“…The reason was that the HANFs were obtained via the hydrolysis of ANF, and in this process the original regularity of the aramid fibers was destroyed to some extent, thus destroying its original crystal structure [ 41 ]. In addition, the fact that some macromolecular chains became ruptured as the amide bonds were hydrolyzed to form amino and carboxyl groups was also an important reason for the decrease in decomposition temperature [ 29 ].…”

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

“…The surface modification technology of aramid fibers mainly includes physical modification technology [7,8,9,10,11], chemical modification technology [12,13], and other modification technologies, including the biological enzymatic method and rare earth modification. [14,15].…”