A facile modification approach for polyacrylonitrile-based UF hollow fiber membrane utilizing polyacrylonitrile-g-poly(vinyl alcohol) graft copolymer

Surface modification of a PES membrane by corona air plasma-assisted grafting of HB-PEG for separation of oil-in-water emulsions

The main goal of this study is to modify a polyethersulfone (PES) membrane by grafting with hyperbranched polyethylene glycol (HB-PEG) using corona air plasma to intensify the anti-fouling properties of the prepared membrane. The separation efficiency and fouling tendency of the modified membranes were evaluated for the treatment of a synthetic oily wastewater. A mechanism was proposed for the HB-PEG grafting on the surface of the corona treated PES membranes and all steps of the grafting were described in detail. The effects of corona treatment operating conditions on the morphology, surface properties, separation performance and anti-fouling efficiency of the modified PES membranes were investigated. Also, the HB-PEG grafted PES membranes were characterized by FTIR, AFM and contact angle analysis. Finally, the HB-PEG grafting on the surface of the PES membranes altered the surface hydrophilicity and led to the improvement of the anti-fouling property and oil–water permeation flux of all modified membranes without any remarkable changes in oil rejection.

The main goal of this study is to modify a polyethersulfone (PES) membrane by grafting with hyperbranched polyethylene glycol (HB-PEG) using corona air plasma to intensify the anti-fouling properties of the prepared membrane.

Improving the Transport and Antifouling Properties of Poly(vinyl chloride) Hollow-Fiber Ultrafiltration Membranes by Incorporating Silica Nanoparticles

Poly(vinyl chloride) (PVC)/SiO₂ nanocomposite hollow-fiber membranes with different nano-SiO₂ particle loadings (0-5 wt %) were fabricated using the dry-jet wet-spinning technique. Effects of SiO₂ nanoparticles on the morphology of the prepared hollow-fiber membranes were investigated using scanning electron microscopy. Transport and antifouling properties of the fabricated membranes were evaluated by conducting pure-water permeation, solute rejection, and fouling resistance experiments. These studies indicated that incorporating silica nanoparticles into the PVC matrix during phase inversion lowers the hydraulic resistance through the membrane and narrows the selective membrane pores. Moreover, the nanocomposite membranes showed better antifouling properties compared to the pristine membrane during the ultrafiltration of a milk solution because of improved hydrophilicity and uniform dispersion of the nanoparticles. This work indicates that embedding silica nanoparticles into the PVC matrix is a promising method for producing cost-effective hollow-fiber ultrafiltration membranes with superior transport and antifouling properties.

Novel modified poly vinyl chloride blend membranes for removal of heavy metals from mixed ion feed sample

Herein, an attempt has been made to prepare a novel membrane with good efficiency for removal of heavy metal ions namely lead (Pb), cadmium (Cd) and chromium (Cr). 4-amino benzoic acid (ABA) was covalently grafted onto the poly vinyl chloride (PVC) backbone by CN bond to enhance the hydrophilicity. ¹H NMR and ATR-IR spectroscopy analysis confirmed the chemical modification of PVC. Further the modified polymer was blended in different compositions with polysulfone (PSf) for optimization. Morphological changes that occurred in blend membranes, due to the incorporation of modified PVC was studied by AFM and SEM techniques. The effect on hydrophilicity and performance of blends owing to incorporation of modified PVC was evaluated by water uptake, contact angle and flux studies. The density of functional groups in blends was analyzed by its ion-exchange capacity. Batch wise filtration of metal ions was carried out and the effect of pressure, feed pH and interference of ions was thoroughly investigated. Essentially, 100% rejection was obtained for all the metal ions in acidic pH with a productivity of 2.56l/m²h. The results were correlated with the results of commercially available NF 270 membrane under the same operating conditions.

Synthesis, Characterization, Thermal Stability and Sensitivity Properties of New Energetic Polymers-PVTNP-g-GAPs Crosslinked Polymers

A series of energetic polymers, poly(vinyl 2,4,6-trinitrophenylacetal)-g-polyglycidylazides (PVTNP-g-GAPs), were synthesized via cross-linking reactions of PVTNP with three different molecular weight GAPs using toluene diisocyanate as the cross-linking agent. The structures of these energetic polymers were characterized by ultraviolet visible spectra (UV–Vis), attenuated total reflectance-Fourier transform-infrared spectroscopy (ATR-FTIR), and nuclear magnetic resonance spectrometry (NMR). The glass-transition temperatures of these energetic polymers were measured with differential scanning calorimetry (DSC) method, and the results showed that all the measured energetic polymers have two distinct glass-transition temperatures. The thermal decomposition behaviors of these energetic polymers were evaluated by differential thermal analysis (DTA), thermogravimetric analysis (TGA) and thermogravimetric analysis tandem infrared spectrum (TGA-IR). The results indicated that all the measured energetic polymers have excellent resistance to thermal decomposition up to 200 °C, and the initial thermal decomposition was attributed to the breakdown of azide group. Moreover, the sensitivity properties of these energetic polymers were measured with the national military standard methods and their compatibilities with the main energetic components of 2,4,6-trinitrotoluene (TNT)-based melt-cast explosive were evaluated by using the DTA method. The results indicate that these energetic polymers have feasible mechanical sensitivities and can be safely used with TNT, cyclotetramethylene tetranitramine (HMX), 1,1-diamino-2,2-dinitroethene (FOX-7), 3-nitro-1,2,4-triazol-5-one (NTO) and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB).

A novel method to prepare a flame-retardant polyvinyl alcohol fiber with modified acrylonitrile coatings

A novel fiber with a PVA substrate and modified PAN coating was constructed, which has favorable tensile strength and flame retardance.

Synthesis and characterization of novel sulfanilic acid–polyvinyl chloride–polysulfone blend membranes for metal ion rejection

A novel facile method is developed for the modification of polyvinyl chloride and blend membranes are fabricated for heavy metal removal. This method is straightforward, has a high efficiency and is done at low pressure.