Effect Of Grafting Parameters Research Articles

Green and Efficient Synthesis of an Adsorbent Fiber by Plasma-induced Grafting of Glycidyl Methacrylate and Its Cd(II) Adsorption Performance

A new chelating adsorbent for the removal of Cd(II) from aqueous solution, PP-g-GMA-DETA fibers, is prepared by plasma induced grafting of glycidyl methacrylate (GMA) onto the surface of polypropylene (PP) fibers, followed by modification with diethylenetriamine (DETA). The effects of grafting parameters on the grafting degree are investigated. Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy prove the successful grafting of GMA onto the surfaces of PP fibers and the subsequent conversion of epoxy groups of grafted GMA to amine groups, on reaction with DETA. The adsorption performances of Cd(II) by the chelating fibers are evaluated in detail. Kinetic and isothermal parameters are also evaluated. The data fit well with the pseudo-second order and Langmuir isotherm model, respectively. The maximum adsorption capacity of Cd(II) is 46.47 mg g-1 and the prepared fibers show selective adsorbability towards target Cd(II) in presence of competing Mg(II) ions.

Effect of Chemical Grafting Parameters on the Manufacture of Functionalized PVOH Films Having Controlled Water Solubility.

This study investigated the chemical grafting of a single-layer poly(vinyl alcohol) (PVOH) film. The effect of the grafting parameters (grafting time, grafting temperature, and concentration of fatty acid chloride) on the hydrophobicity of the film surface and the film solubility were evaluated. The PVOH substrate film (cold-water soluble at 20°C) was manufactured by flat extrusion and had a thickness of 50 μm (±5 μm). The chemical grafting was performed using the transfer method with palmitoyl chloride (C16). The solubility, surface energy, and water vapor transmission rate of the grafted films were measured. The process parameters which produced the most hydrophobic PVOH film were found to be a fatty acid concentration of 3%, a grafting time of 14 min, and a grafting temperature of 130°C. These studies involved systematic adjustment of the hydrophobicity of one side of PVOH films. The results open up opportunities for packing fluids in water soluble packaging.

Catalase immobilized-radiation grafted functional cellulose matrix: A novel biocatalytic system

The work highlights a unique, one step protocol for room temperature immobilization of enzyme catalase onto epoxy functionalised cellulose matrix developed via gamma radiation induced simultaneous irradiation grafting of Glycidylmethacrylate (GMA). Effect of grafting parameters, such as radiation dose, monomer concentration and solvent composition on the grafting yield, was studied in order to optimize the radiation grafting process. Poly(GMA)-g-cellulose matrices were characterized by grafting yield determination, FTIR, SEM and TGA techniques. The epoxy functionalized poly(GMA)-g-cellulose matrix was subsequently employed for covalent immobilization of an industrially relevant enzyme catalase. The catalytic activity of catalase-immobilized-poly(GMA)-g-cellulose was assayed by spectrophotometrically monitoring the enzymatic degradation of H2O2 at 240nm. Catalase-immobilized-poly(GMA)-g-cellulose was observed to be reusable for over 5 cycles within ten days. Catalase was observed to show improved activity at higher pH after immobilization. Thermal stability of Catalase-immobilized-poly(GMA)-g-cellulose was also enhanced in comparison to the free enzyme system.

PREPARATION AND CHARACTERIZATION OF POLY(1-VINYL IMIDAZOLE)-GRAFT-ETFE/PHOSPHORIC ACID PROTON CONDUCTING MEMBRANES

Proton conducting membranes obtained by radiation-induced grafting (RIG) of 1-vinylimidazole (1-VIm) onto poly(ethylene-co-tetraflouroethene) (ETFE) films followed by phosphoric acid (PA) doping was prepared. The effect of grafting parameters on the grafted basic moiety was studied. The level of PA doping was controlled by manipulation of reaction parameters. The obtained membranes were investigated with Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), differential scanning calorimeter (DSC) and DC impedance spectroscopy. The obtained membranes proved to have less-water dependent proton conductivity with a value of 140 mS/cm at 120oC and 17 % RH% at acid doping level of of 6.54 mmol/repeat unit. The membranes have potential for application in high temperature polymer electrolyte membrane fuel cell (PEMFC).

Kinetics of Radiation-Induced Graft Copolymerization of Vinylbenzyl Chloride onto Nylon Fibers

The graft copolymerization of vinylbenzyl chloride (VBC) onto nylon-6 fiber was investigated by the pre-irradiation method using electron beam. The effects of grafting parameters, monomer concentration, absorbed dose and reaction temperature were investigated. The empirical kinetic rate equation dGo/dt=k[M]^0.86*[D]^1.06 was used to describe grafting of VBC onto nylon-6. The overall activation energy for graft copolymerization of VBC was found to be 22.6 kJ/mol. The results revealed that the grafting kinetic was controlled by the amounts of trapped radicals and monomer molecules. Fourier transform infrared (FT-IR) was used to provide evidence for the formation of grafted copolymers.

Surface modification of polypropylene nonwoven fabrics via covalent immobilization of nonionic sugar-based surfactants

Amphiphilic N-alkyl-1-amino-1-deoxy-D-glucitol (CnAG, n=8, 12) were successfully prepared. Polypropylene nonwoven fabrics (PPNWF) were grafted with glycidyl methacrylate (GMA) via a technique of UV-induced graft polymerization combined with plasma pre-treatment, and then PPNWF-g-GMA was used for the covalent immobilization of CnAG. The surface graft polymerization was confirmed by ATR-FTIR and XPS, respectively. Effect of grafting parameters, e.g., acetone content, monomer concentration and UV irradiation time on the grafting density of GMA was investigated. And the hemocompatibility of the modified PPNWF was evaluated by protein adsorption and platelet adhesion. It was founded that the CnAG-modified substrates greatly suppressed protein adsorption and platelet adhesion compared with the native and pGMA-grafted PPNWF.

Argon plasma treatment-induced grafting of acrylic acid onto expanded poly(tetrafluoroethylene) membranes

Expanded poly(tetrafluoroethylene) (ePTFE) is used in facial reconstruction surgery. For some specific applications ePTFE is required to interface with the underlying bone. However, ePTFE is classified as bioinert thus limiting integration at the bone-tissue interface. The incorporation of functional groups onto the ePTFE surface was carried out in the current study using argon plasma treatment-induced grafting of acrylic acid (AA) to improve integration. High surface coverage (grafting extent from XPS of up to 90%) was achieved and resulted in high hydrophilicity and high water uptake (up to 470% of the grafted PAA mass). The contribution of species present in the plasma to the incorporation of functional groups onto the ePTFE surface was evaluated with charged species observed to play an equally important role to neutral species in this study. The effects of sample position in the plasma chamber as well as the effect of grafting parameters (plasma power, monomer concentration, and reaction time) on the grafting outcome were evaluated. The mechanical properties of the AA grafted membranes under tensile, compression and nanoindentation were evaluated.

A Novel Sorbent Prepared by Two-Step Grafting of Acrylic Acid and Methyl Methacrylate Monomer onto a Polypropylene Matrix

In order to improve the hydrophilicity of polypropylene (PP) nonwovens, grafting of acrylic acid (AA) and methyl methacrylate (MMA) onto PP matrix through ultraviolet (UV) radiation was achieved in an isopropanol/water acidic aqueous solution. AA and MMA were grafted onto a pre irradiated PP matrix by a two-step grafting reaction for preparation of a novel composite sorbent PP-g-(AA+MMA). The grafting conditions were optimized and the effects of grafting parameters were investigated. The present study suggested that the grafting degree played a dominant role in the sorption implication of PP-g-(AA+MMA). Fourier transform infrared spectra (FT-IR) and X-ray photoelectron spectra (XPS) were used to characterize the chemical changes of the PP matrix surface. The morphological behaviors have been estimated using specific surface area, porosity and scanning electron microscopy (SEM). Static contact angle (CA) measurements showed that the hydrophilicity of PP nonwoven was enhanced after graft polymerization. The thermal stability of PP-g-(AA+MMA) was evaluated by different thermo analysis (DTG) and differential scanning calorimetry (DSC). The improvement of reusability are shown as the increased of tensile modulus as a function of physical properties.

Preparation of a Hydrophilic PVDF Membranes by Electron Beam Induced Grafting Polymerization of Acrylic Acid

In order to improve the water flux of PVDF hollow-fiber membrane, acrylic acid (AA) was grafted onto PVDF membrane matrix through electron beam irradiation in isopropanol/water aqueous solution. The grafting conditions were optimized and the effects of grafting parameters were investigated. Fourier transform infrared attenuated total reflection spectroscopy (FTIR-ATR) was used to characterize the chemical changes of the PVDF matrix. The morphological behaviors have been estimated using field emitting scanning electron microscopy (FESEM). The present study suggested that the grafting degree played a dominant role in the water flux of AA grafted PVDF membrane (PVDF-g-AA). The pure water flux of grafted membrane increased to 467.8 L/m2h, nearly two times than the original membrane.

Preparation and characterization of phosphoric acid composite membrane by radiation induced grafting of 4‐vinylpyridine onto poly(ethylene‐co‐tetrafluoroethylene) followed by phosphoric acid doping

AbstractPreparation of phosphoric acid composite membranes by radiation induced grafting of 4‐vinylpyridine (4‐VP) onto electron beam irradiated poly(ethylene‐co‐tetrafluoroethylene) film followed by phosphoric acid doping was investigated. The effect of grafting parameters (monomer concentration, absorbed dose, reaction time, and temperature) on the degree of grafting (G%) in the membrane precursor and its relation with the amount of acid doped was studied. The proton conductivity of the obtained membranes was evaluated in correlation with G% and temperature using ac impedance. Fourier transform infrared, thermal gravimetric analysis, X‐ray diffraction, and universal mechanical tester were used to investigate chemical composition, thermal resistance, structure, and mechanical properties of the membranes, respectively. The membranes of 34 and 49% recorded high proton conductivity in the magnitude of 10‐2 S cm‐1 without humidification. The membranes were also found to have reasonable mechanical integrity together with thermal stability up to 160°C. The obtained membranes are suggested to be less‐water dependent and have potential for testing in high temperature polymer electrolyte membrane fuel cell. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

HIGH WATER ABSORBENTS FROM LIGNOCELLULOSES. I. EFFECT OF REACTION VARIABLES ON THE WATER ABSORBENCY OF POLYMERIZED LIGNOCELLULOSES

Hydrogels of 350 water-absorbency (g H2O2/g sample) and 900 water-keeping capacity (mL H2O2/g sample) were prepared from local lignocellulosic wastes. The wastes used are rice straw, sugar-cane bagasse, and cotton stalks. These hydrogels were prepared via graft–polymerization reaction using some vinyl monomers, followed by alkali hydrolysis. The effects of grafting parameters (concentration of both initiator and monomer, temperature, and time), purity of lignocellulose sample, type of monomer, pretreatment of lignocellulose, and manner of saponification reaction were examined. The application of such polymeric materials as soil conditioners, by following the pore size distribution of sand soil, in comparison with conventional soil conditioners (e.g., natural organic fertilizer and clay), were also evaluated.