Study On Radiation Graft Modification And Functionalization Of Ultra-high Molecular Weight Polyethylene Fiber And Fabric

Ultra-high molecular weight polyethylene(UHMWPE)fiber is a kind of high-performance organic fiber,and has excel ent mechanical properties,which has been widely applied in military,medical,chemical and construction fields.However,its low surface energy and nonpolarity restrict its application in the field of materials.In this study,new methods for preparing UHMWPE-based functional polymeric materia ls were offered via combining radiation-induced graft polymerization technique with chemical modification.Four UHMWPE-based functional polymeric materials were successfully prepared,including amidoximated UHMWPE-based fibrous adsorbent,UHMWPE-based fibrous adsorbent containing quaternary ammonium groups,and copper electroless plated UHMWPE fiber(fabric).Firstly,glycidyl methacrylate(GMA)and methyl acrylate(MA)were grafted onto UHMWPE fiber via pre-irradiation induced graft polymerization.Then,amidoxime groups were introduced into the grafted UHMWPE fiber by chemical modification.The effects of different conditions on the degree of graft and the kinetics of the addition reaction of acrylonitrile were studied in detail.The chemical structure,surface morphology,thermal properties,crystal structure and mechanical properties of UHMWPE fiber before and after modification were evaluated.It was shown that the amidoximated UHMWPE fiber had been successfully prepared and retained the excel ent mechanical properties of UHMWPE fiber to the greatest degree.The adsorption performance of the amidoximated UHMWPE fibrous adsorbent was evaluated by subjecting it to an adsorption test in simulated seawater using flowthrough mode.The amount of uranium adsorbed by this AO-based UHMWPE fibrous adsorbent was 1.97 mg-U/g after 42 days and showed high selectivity for the uranyl ion.Secondly,UHMWPE fiber grafted with GMA was modified with triethylenetetramine and 2,3-epoxypropyltrimethylammonium chloride to prepare fibrous adsorbent containing quaternary ammonium groups.And ATR-IR and SEM were used to investigate the chemical structure and morphological changes of UHMWPE fiber before and after modification.This novel fibrous adsorbent was applied to the adsorption of Cr(VI)ions.The principal factors affecting the adsorption of Cr(VI)ions have been investigated including p H of the aqueous solution,the degree of graft,initial concentration,and coexisting anions.The adsorption kinetics,isotherm and reusable conditions were discussed.In addition,regeneration performance and adsorption mechanism of the materials were also studied.The results showed that the maximum adsorption capacity of Cr(VI)was 276 mg/g and the optimum p H value was 3.It was found that adsorption equilibrium could be achieved within 2 h for initia l Cr(VI)of 100 mg/L,following the pseudo-second order model.The adsorption isotherm studies showed that the adsorption behavior of the fiber was in good agreement with the Langmuir adsorption isotherm model.The adsorption saturated fiber could be regenerated by soaking in 0.5 mol/L Na OH solution,and the adsorption performance of this adsorbent could be maintained at 90% after eight cycles of adsorption-desorption.The coexistence of anions led to a decrease in the adsorption capacity of Cr(VI)and its effect on the adsorption efficiency was this: SO42-> H2PO4-> NO3-> Cl-.ATR-IR and XPS analysis revealed that Cr(VI)ions were adsorbed on the fiber adsorbent through ion exchange mechanism.Thirdly,acrylic acid was successfully grafted onto the UHMWPE fibers in aqueous solution via pre-irradiation grafting method,and chemical structure of the fiber was characterized by ATR-IR.Then UHMWPE-g-PAAc fiber was immersed in silver nitrate solution to absorb silver ions,and subsequently placed in a plated bath with formaldehyde as a reducing agent for subsequent electroless deposition of copper to yield conductive UHMWPE fiber,which surface was coated with hermetically unifo r m layers.The resistivity of copper-deposited UHMWPE fiber was 1.4×10-5 Ω?cm.The morphology,thermal stability,and mechanical properties of UHMWPE fiber before and after grafting and ELD were characterized by SEM,TG,and monofilament strength testing.The copper-deposited UHMWPE fiber would be very easily oxidized in the air,which resulted in the gradual decreasing of conductivity and affect the long term performance.In order to prove the strength between the fiber and the copper layer,the copper-deposited UHMWPE fiber was accelerated washed according to the AATCC61-2006 standard,and the results showed the copper layer is firmly bonded with the fiber.Lastly,UHMWPE-based organic-inorganic hybrid fabric was successfully prepared via combining simultaneous radiation-induced graft polymerization and selfassembly,which was characterized by ATR-IR,XPS,and 29Si-NMR.UHMWPE-gPMAPS-NAPTES fabric was immersed in chloropalladic acid solution to absorb Pd Cl42-ions,and then placed in a plated bath with sodium hypophosphite as a reducing agent for subsequent electroless deposition of copper to yield conductive UHMWPE fabric.The surface resistance of copper-deposited UHMWPE fabric was 5.45×10-2 Ω/sq.The morphology,thermal stability,and crystal structure of UHMWPE fabric were characterized by SEM,TG,and XRD.In order to improve the oxidation resistance of copper-deposited UHMWPE fabric,nickel electroless deposition was processed on copper-deposited UHMWPE fabric to obtain nickel-copper coated metal iza t io n conductive fabric to protect the copper layer.Electromagnetic shielding effect of UHMWPE fabrics after copper and nickel deposition were measured by a vector network analyzer,and the results showed that nickel-copper coated UHMWPE fabric could shield 94.5% of the electromagnetic wave in the frequency range of 8~12 GHz.