| Due to their high strength, high Young’s modulus, PPTA fiber has been widelyapplied as a reinforced material in aerospace, shipbuilding, automotive and specialtyproduct development. However, its lower surface polarity and chemical inertness alsogreatly limit its scope of application as a composite material. However, with the expansionof aramid poducts the scale of production and demand, waste has been a gradual increase.Consequently, based on the improvement of aramid composite interfacial bonding andavoid waste aramid pollution environment, the amphiphilicity structure of the epoxygroup modified PPTA coating agent and para-aramid supported amidoxime adsorbentmaterials. A series of synthetic materials were characterized, and its properties werestudied.In this paper, adopting metalized/substitution reaction, poly(p-phenyleneterephthalamide)(PPTA) as the substrate, epichlorohydrin as the modifier, epoxy groupmodified PPTA (PPTA-ECH) was prepared, which was used as a coating agent forKevlar cloth. The coating agent of the resultant PPTA-ECH was characterized byFourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA)and transmission electron microscopy (TEM). The coated fiber was characterized by afield emission scanning electron microscopy (FE-SEM) and X-ray photoelectronspectroscopy (XPS). The interlaminar shear strength (ILSS) and the in-plane shearstrength of PPTA-ECH coated PPTA/resin composite were carried out by anINSTRON5982determined All-purpose Electronic Tester. Simultaneously, a coatingmechanism for PPTA filaments was predicted. The infrared spectroscopy resultsindicate that the epoxy groups were successfully introduced to PPTA particle surface.The thermogravimetric analysis showed that the thermal stability of PPTA-ECH is~40K lower than that of PPTA powder. The TEM images proved that the sodiummetallization PPTA(PPYA(Na)) and PPTA-ECH were nano-structure, PPTA(Na) isnanofibers with diameters between20and50nm, PPTA-ECH polymer is50-200nmnanoparticles with regular core-shell structure. The field emission scanning electronmicroscopy demonstrated that a PPTA-ECH coating layer was formed on the fibersurface. It is clear that two new peaks at286.56eV(C1s) and532.65eV(O1s) wereobserved on the PPTA-ECH coated PPTA fiber by XPS, which are attributed to the epoxy groups, this was further evidence that the coating agent was coated on the fibersurface. The properties of the composite material by testing found that after the coatingcoated composite the interlaminar shear strength and the in-plane shear strengthenhanced, and the increasing order is PPTA-ECH (pure)> PPTA-ECH> PPTA (Na).Synthesis, characterization and adsorption properties of para-aramid loadedamidoxime materials were studied in this paper in order to improve the comprehensiveutilization of para-aramid. The cyano groups were introduced on PPTA surface byacrylonitrile, and then the cyano groups were converted to amidoxime due tohydroxylamine hydrochloride, because of different amounts of reactants，obtainingthree amidoxime adsorbent material(namely PPTA-AO1, PPTA-AO2, PPTA-AO3). Theadsorbent material was characterized by Fourier transform infrared spectroscopy(FT-IR), thermogravimetric analysis (TGA) and Elemental analysis (EA). These resultsshow that the amidoxime groups are successfully loaded on the PPTA. The adsorptionproperties of the amidoxime adsorbent materials were investigated towards Hg(Ⅱ),Ag(I), Cu(Ⅱ), Pb(Ⅱ), Cd(Ⅱ) and Ni(Ⅱ). The experiments show that the amidoximeadsorbent materials have good adsorption performance for Hg (Ⅱ). The adsorptionkinetics, isotherms, selectivity were mainly studied towards Hg (Ⅱ). Moreover，thecomparison of adsorption capacities of PPTA-AO with other adsorbents for Hg(Ⅱ),Cu(Ⅱ), Pb(Ⅱ). The adsorption kinetics indicates that the pseudo second-order modelcan reasonably describe the adsorption kinetics of three adsorbent materials for Hg (Ⅱ).Thermodynamics adsorption experiments showed that Langmuir model can betterdescribe the process of mercury adsorption for PPTA-AO1, PPTA-AO2; the adsorptionprocess for Hg (Ⅱ) is governed by monolayer. Freundlich model is more suitable todescribe the isothermal adsorptions of Hg (Ⅱ) on PPTA-AO3. The thermodynamicparameter of positive△H, positive△S and negative△G showed endothermic heatof adsorption, the increased randomness at the solid–solution interface and thespontaneous nature of the adsorption process, respectively. Adsorption selectivityexperiments indicated that the three materials own good adsorption selectivity for Hg(Ⅱ) in some binary-components solutions containing Hg (Ⅱ). By comparisonPPTA-AO adsorption capacities with other adsorbents，the adsorption capacities ofPPTA-AO for Hg(Ⅱ), Cu(Ⅱ), Pb(Ⅱ) is higher, these can remove Hg(Ⅱ), Cu(Ⅱ), Pb(Ⅱ) in the aqueous solution, which is of great importance for the resources recycling andpropecting the environment. |
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