Permeation and Separation Characteristics of Acetic Acid‐Water Mixtures by Pervaporation through Acrylonitrile and Hydroxy Ethyl Methacrylate Grafted Poly(vinyl alcohol) Membrane

Abstract

In this study, acrylonitrile (AN) and hydroxyl ethyl methacrylate (HEMA) were grafted onto poly(vinyl alcohol) (PVA) using cerium (IV) ammonium nitrate as initiator at 30°C. The graft copolymer was characterized using the Fourier transform infrared spectroscopy (FTIR) and elemental analysis. The grafted PVA membranes (PVA‐g‐AN/HEMA) were prepared by a casting method, and used in the separation of acetic acid‐water mixtures by pervaporation. The effects of the membrane thickness, operating temperature, and feed composition on the permeation rate and separation factor for acetic acid‐water mixtures were studied. Depending on the membrane thickness, the temperature and feed composition PVA‐g‐AN/HEMA membranes gave separation factors 2.26–14.60 and permeation rates of 0.18–2.07 kg/m²h. It was also determined that grafted membranes gave lower permeation rates and greater separation factors than PVA membranes. Diffusion coefficients of acetic acid‐water mixtures were calculated from permeation rate values. The Arrhenius activation parameters were calculated for the 20 wt.% acetic acid content in the feed using the permeation rate and the diffusion data obtained at between 25–50°C.     

Radiation Graft Co-polymerization of Methacrylic Acid (MAA) onto Sago Starch Films

Abstract

In this work, the factors that may affect the gamma radiation-induced grafting of methacrylic acid monomer (MAA) onto sago starch films were investigated. The graft copolymers were characterized by tensile mechanical testing, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and infrared spectroscopy. The results showed that the highest grafting yield was obtained within the irradiation dosage level of 10–20 kGy and by using monomer concentration range of 15–20 wt%. The highest tensile mechanical properties were observed for sago starch films having 66% graft yield of MAA. The DSC thermograms indicated a decrease in the gelatinization temperature (temperature at which the disruption of the molecular orders in the starch granules occurs) of sago starch as a result of grafting. This behavior was explained on the basis that radiation grafting prevents the retrograddation process of starch (starch re-crystallization). On the other hand, the IR spectra indicate an increase in the intensity of the absorption band due to C?O stretching, confirming the occurrence of grafted chains of MAA.     

Graft copolymerization of n-vinyl-2-pyrrolidone on dimethyl sulfoxide pretreated poly(ethylene terephthalate) films using azobisisobutyronitrile initiator

Poly(ethylene terephthalate) (PET) films were grafted with n-vinyl-2-pyrrolidone (n-VP) using an azobisisobutyronitrile (AIBN) initiator. Films were pre-treated in dimethyl sulfoxide (DMSO) for 1 h at 140°C before the polymerization reaction was carried out. Variations of graft yield with time, temperature, initiator, and monomer concentrations were investigated. The optimum temperature and polymerization time was found to be 70°C and 4 h, respectively. Increasing monomer concentration from 0.28 to 1.22M and initiator concentration from 1.77 × 10⁻³ to 4.20 × 10⁻³M enhanced the percent grafting. The effects of monomer and initiator diffusion on PET films were also studied. The overall activation energy for grafting was calculated as 11.5 kcal/mol. Further changes in properties of PET films such as water-absorption capacity and intrinsic viscosity were determined. The grafted films were characterized with FTIR and scanning electron microscopy (SEM). © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1437–1444, 1997     

Preparation of proton exchange membranes by radiation-induced grafting of alpha methyl styrene–butyl acrylate mixture onto polyetheretherketone (PEEK) films

Radiation-induced graft copolymerization of alpha methyl styrene (AMS)–butyl acrylate (BA) mixture onto poly(etheretherketone) (PEEK) was carried out to produce copolymer films which were subsequently sulfonated to develop proton exchange membranes. The characterization of membranes was carried out with infrared spectroscopy (FTIR), differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction analysis (XRD), contact angle and electron probe microanalysis (EPMA). The presence of sulfonic acid groups within the polymer matrix was confirmed by FTIR. The crystallinity of membranes decreased significantly upon sulfonation process. The melting temperature of the membranes also decreased as compared to the virgin and the grafted films. At the same time, glass transition temperature (T _g) of membranes increased as the grafting increased. Virgin film showed stable thermogram up to ~500 °C while the grafted film had two-step degradation pattern. Sulfonation introduced one additional decomposition range in the membrane. Contact angle images showed the hydrophilic nature of the membrane surface. The EPMA showed the presence of the sulphur across the membrane matrix in a homogenous manner. The membranes showed low resistivity of 62 Ω cm for the graft level of 27 %.     

Surface functionalization of polyolefin films via the ultraviolet‐induced photografting of acrylic acid: Topographical characterization and ability for binding antifungal agents

The photoinduced graft copolymerization of acrylic acid with ultraviolet radiation onto films of poly(vinyl chloride), polypropylene, and polyethylene was studied. Benzophenone was used as the initiator for most of the experiments performed. The percentage of grafting was determined by gravimetric measurements, and the characterization of the grafted films was carried out by chemical analysis (Fourier transform infrared spectroscopy, volumetric titration, and dye adsorption). In all samples, the grafted yield increased with the ultraviolet exposure time. High levels of grafting were obtained at room temperature. In addition, optical and atomic force microscopy allowed the topography of the modified films to be studied as a function of the reaction time. The pendant functional groups that were grafted were then used to bind antifungal agents, such as natamycin and crystal violet, and the antifungal properties of the films were demonstrated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:2254–2263, 2006     

Self‐driven graft polymerization of vinyl monomers on poultry chicken feathers in the absence of initiator/catalyst

An efficient and simple method for graft copolymerization of powdered chicken feather (CF) with vinyl monomers without any free radical initiator is reported. Various vinyl monomers such as glycidyl methacrylate (GMA), styrene (S), and methyl methacrylate (MMA); (20–60 wt % with respect to CF) were successfully grafted to chicken feather (CF) by using sodium dodecyl sulfate (SDS, 0.086–0.5 mmol) in the absence of any catalyst or initiator. Most likely, the hydrophilicity, hydrophobicity, and complex forming properties of chicken feather keratin with surfactant molecules were responsible for efficient grafting of polymers on CF surface. The effect of polymerization conditions, such as monomer concentration, temperature, and time of reaction, on the grafting parameters such as monomer conversion, grafting efficiency, and molar grafting ratio were studied. The described method showed a good potential of using low cost, easily accessible poultry chicken feathers as grafting material and self catalyzing agent for graft copolymerization with vinyl monomers to produce low cost commodity plastic for various end uses. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44645.     

Surface modification of nylon membrane by glycidyl methacrylate graft copolymerization for antibody immobilization

Surface of nylon membrane was modified by the graft copolymerization of glycidyl methacrylate (GMA) using persulfate and thiosulfate as redox initiator system. Effect of various reaction parameters such as initiator concentration, monomer concentration, polymerization time, and temperature on degree of grafting was also studied. Maximum grafting of 100% was achieved by using equimolar concentration (0.008M) of redox initiator and 0.5M of GMA monomer at 70°C in 60 min. Grafted nylon membranes with various graft levels of GMA were characterized by various techniques such as fourier transform infrared spectroscopy, thermo gravimetric analysis, and scanning electron microscopy. The GMA grafted nylon (NyM‐g‐GMA) membranes with different graft levels were evaluated as a support for immobilization of rabbit anti goat antibody (RAG IgG). Antibody (Ab) immobilized NyM‐g‐GMA membranes were evaluated using ELISA and Bradford protein estimation method. Nylon membrane with 60% graft level showed optimum immobilization of Ab at RAG IgG conc. of 0.625 μg/mL with low nonspecific binding. Maximum immobilization efficiency (I.E.%) of 56% was observed for membrane with 60% graft level at 50 μg/mL of RAG IgG in PBS (pH 7.4). Ab immobilized NyM‐g‐GMA discs were found to be stable up to 6 weeks at 4°C and 2 days at 37°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

HEMA‐grafted chitosan for dialysis membrane applications

Chitosan was graft copolymerized with HEMA (2‐Hydroxyethylmethacrylate) for the development of blood‐compatible dialysis membranes. The permeation characteristics of HEMA‐grafted chitosan films for four different solutes creatinine, urea, glucose, and albumin was studied in vitro at 37°C for assessment of the suitability as dialysis membranes. The grafted film CH‐12.5 composition (425% grafting) showed very high permeation to creatinine by reaching the equilibrium within 45 min. The compositions CH‐7.5 and CH‐12.5 showed excellent permeation to glucose when compared to virgin chitosan films. In the case of urea permeation, all the grafted compositions exhibited higher percent permeation than the virgin chitosan films. The copolymer films CH‐7.5 and CH‐12.5 showed enhanced permeability for the high molecular weight solute, albumin. The other grafted copolymer compositions followed almost the same trend as that of chitosan for the low molecular weight solutes as well as the high molecular weight solute. The copolymer films were also found to be highly blood compatible, noncytotoxic, and biodegradable. Hence, the need for developing blood‐compatible chitosan membranes with desirable permeability properties is achieved by the graft copolymerization of HEMA onto chitosan. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2960–2966, 2006     

Preparation and Characterization of a Graphene Oxide Film Modified by the Covalent Attachment of Polysiloxane

Hybrid materials consisting of polydimethylsiloxane (PDMS) and polycyclohexyl-methylsiloxane (PCHMS) grafted graphene oxide (GO) were obtained by condensation polymerization in toluene. Fourier transform infrared spectroscopy indicates that the composites were synthesized through the formation of Si-O bond. The X-ray diffraction, scanning electron microscopy and thermogravimetric indicate that the hydrolysis polycondensation can accelerate the graft reaction. The hybrid films were prepared by simple filtration of the dispersed system of PDMS/GO/water, PCHMS/GO and PCHMS/GO/water in dimethylformamide. Tensile tests indicate the mechanical properties of the films varied with their structure. The rigid PCHMS/GO/water films have a tensile strength of 17.83 MPa, and the pliant PDMS/GO/water films have an elongation at break of 3.14%. UV-Vis spectra of GO and the hybrids indicate that the addition of polysiloxane caused a red-shift (10–20 nm) of the absorption peak.     

Iron(III) complexed with radiation‐grafted acrylic acid onto poly(tetrafluoroethylene‐co‐perfluorovinyl ether) films

To introduce functional moieties to a poly(tetrafluoroethylene‐co‐perfluorovinyl ether) film, graft copolymerization of vinyl monomers such as acrylic acid was attempted by a simultaneous technique in aqueous solution using γ‐irradiation. The graft copolymers were complexed with the Fe(III) in aqueous solution. The grafted copolymer–metal complexes were examined by infrared (IR), ultraviolet/visible, energy‐dispersive X‐ray spectroscopy, and electron spin resonance techniques. The effect of temperature on the trunk copolymer, untreated grafted, and treated grafted copolymer films was investigated by IR and thermogravimetric analysis. The overall results suggest octahedral structure for Fe(III) and revealed the high stability of the obtained ligand–metal complexes. Furthermore, scanning electron microscope investigation of the grafted and modified films, both unheated and heated (200°C), showed changes in the structure and surface morphology. Promising results were achieved enhancing the practical applications of modified grafted membranes in the recovery of metal ions from aqueous systems. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 4065–4071, 2007     

Synthesis and characterization of butyl acrylate graft sodium salt of partially carboxymethylated starch

Graft copolymers were synthesized by graft copolymerization of butyl acrylate (BA) onto sodium salt of partially carboxymethylated starch (Na‐PCMS). Ceric ammonium nitrate (CAN), a redox initiator, was used for initiation of graft copolymerization reaction. All the experiments were run with Na‐PCMS having degree of substitution, DS = 0.35. The grafting reaction was characterized by parameters such as % total conversion (%Ct), % grafting (%G), % grafting efficiency (%GE), and % add‐on. Graft copolymers were characterized by infrared spectral analysis and scanning electron microscopy. Variables affecting graft copolymerization reaction such as nitric acid concentration, reaction time, reaction temperature, and ceric ion concentration were investigated. The results revealed that 0.3M CAN as initiator, 0.3M HNO₃, with reaction time 4–4.5 h at 25–30°C were found as suitable parameters for maximum yield of graft copolymerization reaction. © 2006 Wiley Periodicals, Inc. JAppl Polym Sci 102: 3334–3340, 2006     

Investigation of poly(methyl acrylate) grafted chitosan as a polymeric drug carrier

The graft copolymerization of methyl acrylate (MA) onto chitosan in aqueous medium was investigated using potassium persulfate (KPS) as initiator. The grafting conditions were optimized by studying the effects of the polymerization variables (the initiator concentration, the ratio of monomer to chitosan, and reaction temperature) on the percentage of grafting (PG). PG was found to depend on these variables, and the highest grafting percentage (256 %) could be obtained at chitosan = 1 g, KPS = 4.5 × 10^?3 M, methyl acrylate monomer = 6 g, T = 60 °C and t = 180 min. The graft copolymer was characterized by Fourier transform infrared spectra analysis, thermogravimetry (differential thermogravimetry, differential scanning calorimetric), X-ray powder diffraction as well as CP-MAS ¹³C NMR spectroscopy. These analyses are highly confirmed the formation of poly(methyl acrylate) grafted chitosan (PMAGC). Furthermore, the gelation of the grafted polymers (PG 68, 122, 218 and 256 %) in distilled water has been studied, and the results revealed that the percentage of swelling number increase with increasing PG of the polymers. Controlled release of niacin (vitamin B₃) from the hydrogel of the grafted polymers (PG 68, 122 and 256 %) in aqueous medium has been studied using ultraviolet absorption to follow quantities released at different times (for each experiment: PMAGC 100 mg, niacin 2.46 mg, distilled water 100 ml). The study was repeated again with same conditions except the using of 4.92 mg of niacin instead of 2.46 mg (PG of the grafted polymer is 256 %). The diffusion coefficient (D, cm²/h) of niacin from the hydrogel of the grafted polymer (PG 256 %) was calculated depending on Higuchi model (diffusion coefficient of the first load is 0.00194 cm²/h while 0.00255 cm²/h of the second load).     

Chemically induced graft copolymerization of acrylic acid onto cellophane films

Grafting of acrylic acid (AA) onto cellophane films was studied using ferrous ion- hydrogen peroxide a redox initiator system. Different variables affecting the graftingyield, graft efficiency and total weight conversion were studied. The swelling properties as well as I.R. spectroscopy analysis of the grafted films were also examined in the hope of developing improved membranes.     

Graft copolymerization of an itaconic acid/acrylamide monomer mixture onto poly(ethylene terephthalate) fibers with benzoyl peroxide

A mixture of acrylamide (AAm) and itaconic acid (IA) was grafted onto poly(ethylene terephthalate) (PET) fibers with benzoyl peroxide in aqueous media. The effects of polymerization conditions such as the temperature, polymerization time, initiator concentration, and monomer mixture ratio on grafting were investigated. The maximum graft yield was 76.1% with an AAm/IA mixture ratio of 90/10 (mol/mol). The graft yield was as low as 3% in the single grafting of IA, whereas the use of AAm as a comonomer increased the amount of IA that entered the fiber structure to 33.5%. An increase in the temperature from 65 to 85°C increased the grafting rate and saturation graft yield. However, an increase in the temperature above 85°C decreased the saturation graft yield. The graft yield increased up to an initiator concentration of 1.0 × 10^?2 M and decreased afterwards. The grafting rate was 0.65th‐ and 0.74th‐order with respect to the initiator and AAm concentrations, respectively. The densities, diameters, and moisture‐regain values of the AAm/IA‐grafted PET fibers increased with the graft yield. Similarly, there was an increase in the dyeability of the AAm/IA‐grafted fibers with acidic and basic dyes. The grafted fibers were characterized with Fourier transform infrared and thermogravimetric analysis, and their morphologies were examined with scanning electron microscopy. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1795–1803, 2005     

Preparation of soapless latexes by sonification of starch-based poly(isoprene–co–acrylonitrile) graft reaction mixtures

Graft copolymerization of isoprene (IP) and acrylonitrile (AN) onto gelatinized starch (S) and cationic starch having quaternary amine functionality through cerium(IV) initiation gave grafted side chains of poly(IP–co–AN). Grafts of various compositions are obtained by controlling the amounts and ratios of monomers added to starch. IP alone does not homograft onto gelatinized starch at 25° or 50°C by cerium(IV) initiation and requires the presence of an “initiator–monomer” such as AN to obtain copolymer side chains. Although cografting of IP and AN onto starch depends on AN to initiate radical chains, the ratio employed of the two monomers is critical for graft polymerization to occur. For example, at a molar ratio of IP to AN of 1 or greater, little polymer was produced; at molar ratios in the range of 0.4 to 0.67, considerable amounts of polymer were produced; and at a molar ratio of 0.13 or less, polymerization of AN was greatly retarded. Concentration of HNO₃ in the cerium(IV) reagent and reaction temperature also influence the grafting reaction. Lower HNO₃ concentrations favor grafting at 50°C, while higher acid concentrations favor grafting at 25°C. Starch graft reaction mixtures were sonified at 20 kHz to form latexes that air dry to clear pliable films. Poly(IP–co–AN) obtained by acid hydrolysis of the starch portion of the grafts failed to dissolve in either dimethylformamide or benzene, thus indicating presence of crosslinks. S–g–poly(IP–co–AN), having about one third starch and grafted side chains averaging about 2 parts polymerized IP per part of polymerized AN, was masticated on steel rolls at 100°C to a tough pliable film which was subsequently vulcanized to a rubber.     

Radiation grafting of acrylic and methacrylic acids onto poly(tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride) TFB films

A study has been made for the preparation of membranes by the direct radiation grafting of acrylic and methacrylic acids onto poly(tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride) TFB films. The appropriate reaction conditions were selected under which the graft polymerization was carried out successfully. In this grafting system, ammonium ferrous sulfate (Mohr's salt), ferric chloride, and cuppric chloride were used as inhibitors to minimize the homopolymerization of acrylic acid and methacrylic acid. Also, the effect of monomer concentration on the rate of grafting was investigated. The dependence of the grafting rate on monomer concentration was found to be of the order of 1.1 and 1.0 for acrylic acid and methacrylic acid, respectively. This grafting system was proceeded by a front mechanism. Some selected properties of the grafted films such as swelling behavior, dimensional change, and mechanical and electrical properties were investigated. It was found that the grafted membranes possess good hydrophilic properties that may make them promising in some practical applications. © 1993 John Wiley & Sons, Inc.     

Selective removal of some heavy metal ions from aqueous solution using treated polyethylene-g-styrene/maleic anhydride membranes

Radiation graft copolymerization of styrene/maleic anhydride (Sty/MAn) comonomer onto low density polyethylene (LDPE) membrane was investigated. The prepared grafted membranes were treated with different reagents containing various functional groups and studied as a matrix for the purpose of water purification from heavy metals. The metal ion uptake by the functional groups of membranes was determined by the use of X-ray fluorescence (XRF) and atomic absorption (AA). The effect of pH of the metal feed solution and immersion period needed for maximum capacity was investigated. The selectivity of different prepared membranes towards some selected metal ions such as Fe, Cu, Pb,… etc. which commonly exist in waste water was determined. The affinity of the treated grafted films to recover Fe(III), Cu(II) or Pb(II) from their aqueous solutions containing other metal ions such as Cd(II), Ni(II) or Hg(II) was studied. Also the selectivity of treated grafted membranes towards Cu(II), Cr(III) and Fe(III) in a mixture was investigated at room temperature and 70°C. It was found that the thiosemicarbazide-, hydroxylamine·HCl- and NaOH-treated grafted films showed high selectivity towards Cu(II), Cr(III) and Fe(III), respectively, at 70°C. However, the selectivity of such treated grafted membranes was remarkable towards Fe(III) at room temperature. The results obtained suggested that the treated grafted membrane possessed good chelating properties towards different metal ions. This suggests that such membranes could be accepted for practical uses.     

Synthesis and characterization of biodegradable polyethylene by graft copolymerization of starch using glucose–Ce(IV) redox system

Graft copolymerization of low‐density polyethylene (LDPE) onto starch was carried out with glucose–cerium(IV) redox initiator in an aqueous sulfuric acid medium under nitrogen atmosphere. The graft yield was influenced by various parameters like reaction time, temperature, and concentrations of acid, glucose, polyethylene (PE), starch, and initiator. A maximum graft yield of 85.66% was obtained at a temperature of 50°C and at higher concentration of starch. Effect of grafting on crystallinity, morphology, and thermal properties of modified PE has been evaluated using X‐ray diffraction, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA/DTA). Biodegradability of starch‐grafted PE has been tested applying soil‐burial test. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3229–3239, 2006     

以Fe2+-H2O2氧化还原体系引发木薯淀粉与醋酸乙烯酯接枝共聚反应研究

研究了以Fe2+-H2O2为引发剂的木薯淀粉与醋酸乙烯酯的接枝共聚反应,并对重要的反应条件进行了讨论。结果表明:当单体与淀粉的质量配比为1.0~2.0,引发剂浓度为1.0 mmol/L,H2O2与Fe2+的摩尔比为2,反应温度为40°C,反应时间为3 h,采用Fe2+→单体→H2O2的加料顺序时,可以得到较高的转化率、接枝率、接枝效率,分别为86.47%、55.30%及31.98%,并探讨Fe2+-H2O2的引发机理。通过Srectrum One红外光谱及电镜对接枝物的结构进行了分析。     

Preparation of gelatin–N-vinylpyrrolidone graft copolymer

The graft copolymerization of N-vinylpyrrolidone (VP) onto gelatin was carried out by the following four different initiator systems: AIBN, K₂S₂O₈, H₂O₂—Fe²⁺, and Ce⁴⁺—HNO₃. The last one caused the monomer to lose the double-bond and polymerization ability due to the hydrolysis of the monomer. Using α,α-azobisisobutyronitrile as an initiator, the graft copolymerization of gelatin and N-vinylpyrrolidone in aqueous medium was studied systematically. The relationships between the rate of grafting and the concentration of initiator, monomer, and gelatin were established experimentally. Meanwhile, the rate equation was also derived from the proposed reaction mechanism, and it was similar to the equation previously obtained experimentally. The apparent activation energies for homopolymerization (E_h), graft copolymerization (E_g), and over all polymerization (E_p) were calculated. The graft efficiency and molecular weight of the grafted PVP were measured by hydrolyzing the backbone with hydrochloric acid. The graft copolymers Gel-g-PVP were added into the coating films, and the physical properties of the films, such as hardening ability, dimensional stability, and wetting property were investigated. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1485–1492, 1998