Grafting Of Acrylonitrile Research Articles

Comparative examinations of reactivity of grafted celluloses prepared by u.v.- and ceric salt-initiated graftings

Grafting of glycidyl methacrylate (GMA) and acrylonitrile (AN) on cellulose was carried out in u.v.- and ceric salt (Ce 4+)-initiation systems. The u.v.-initiation system using hydrogen peroxide as a photoinitiator was characterized with a considerably low grafting rate compared to the Ce 4+-initiation system. The resultant GMA- and AN-grafted celluloses were subjected to reactions with triethylenetetramine (Trien) and hydroxylamine, respectively, to compare the reactivity between the grafted samples (u.v.- and Ce 4+-samples) prepared in the u.v.- and Ce 4+-initiation systems. The u.v.-sample exhibited higher reactivity than the Ce 4+-sample toward each reaction. The samples containing Trien and amidoxime groups showed an ability to absorb cupric ion, which was nearly equal among the two samples. The difference in the reactivity between the two samples was discussed in terms of the structure of grafted cellulose, which was characterized with average molecular weight and number of grafted chains and moisture regain of the samples.

Studies on graft copolymerization of acrylonitrile onto jute fiber with permanganate ion initiation system in presence of air

AbstractThe graft copolymerization of acrylonitrile with jute using potassium permanganate as the initiator has been studied in the presence of air. To establish reaction conditions for the graft copolymerization of acrylonitrile (AN) onto jute, the effect of different variables such as the residual lignin content of bleached jute (after bleaching with sodium chlorite), initiator concentration, monomer concentration, time of polymerization, reaction temperature, and amount of bleached jute fiber have been studied. As evidence of polymer grafting, some instrumental analyses such as scanning electron microscopy, infrared, and thermogravimetry have been carried out. The extent of grafting of acrylonitrile depends on how much lignin is present on the jute fiber. Percent grafting and grafting efficiency have also been studied. © 1995 John Wiley & Sons, Inc.

Radiation graft modification of ethylene-propylene rubber—II. Effect of additives

The effect of multifunctional acrylic additives including TMPTA, PEGDA and PGTA on the radiation grafting of hydrophilic vinyl monomers onto ethylene—propylene elastomer (EPM rubbers) was studied. This work centres upon gamma irradiation-induced grafting of acrylamide (AAm), N-vinyl-2-pyrrolidone (NVP), 2-hydroxyethyl methacrylate (HEMA) and acrylonitrile (AN) onto EPM rubber by the simultaneous method. Water proved to be an effective solvent but methanol lowered grafting. Sulphuric acid was detrimental to both homopolymerisation and grafting, a result consistent with the theory proposed for the role of this additive in polymer grafting systems.

Radiation graft modification of ethylene-propylene rubber—I. Effect of monomer and substrate structure

Radiation grafting of hydrophilic vinyl monomers onto ethylene-propylene elastomers (EPM rubbers) by the simultaneous method was studied. The present work centres upon gamma radiation-induced grafting of acrylamide (AAm), N-vinyl-2-pyrrolidone (NVP), 2-hydroxyethyl methacrylate (HEMA) and acrylonitrile (AN) onto four different EPM rubbers. Metal-based homopolymerisation inhibitors including Mohr's salt, Cu(NO 3) 2 and FeSO 4 were evaluated and found to prevent homopolymerisation and significantly increase graft yield. Lithium nitrate was evaluated as a graft promoter. The effect of oxygen upon grafting was also studied. The role of the type of EPM rubber on grafting efficiency for a variety of monomers was investigated, to optimise grafting conditions for each EPM rubber and monomer. The properties of the resulting copolymers have been studied by SEM techniques.

Ceric-induced grafting of acrylonitrile onto sodium alginate: kinetics and mechanism and effects of the reaction medium

The kinetic scheme of free radical graft copolymerization of acrylonitrile (AN) onto sodium alginate, using ceric ammonium nitrate as an initiator, has been proposed and equations relating the values of Rp, Rr and Rh are also suggested. The results have been found to be in good agreement with the proposed mechanism. The per cent grafting of AN onto sodium alginate has also been determined as a function of composition of the mixed solvents comprising methanol: water, ethanol: water, n-propanol:water and n-butanol: water systems. The reaction medium has been found to play an important role in graft copolymerization. The results of the effect of the reaction medium on grafting are also discussed.

Kinetics and reaction mechanism of fenton's‐reagent‐initiated graft copolymerization of acrylonitrile onto sodium alginate

AbstractThe kinetics and mechanism of grafting of acrylonitrile (AN) onto sodium alginate (SA) using Fenton's reagent (Fe2+–H2O2) has been studied. The experimental results are found to be in good agreement with the proposed kinetic scheme. © 1994 John Wiley & Sons, Inc.

Thermal behavior of ungrafted and grafted bagasse and wood pulps

AbstractThe effect of grafting of methyl methacrylate (MMA) and acrylonitrile (AN) on the thermal behavior of the pulp of sugar cane loaded with CaCO3 and the pulp of a broad‐leaved tree has been studied by thermal methods. Different experimental conditions of grafting AN onto the eucalyptus pulp have been used, including both water and organic solvent systems as the medium of reaction. To optimize the grafting of MMA onto wood pulp, the effect of pulp swelling and the contact time of the monomer with the pulp have been examined. Ungrafted as well as grafted cellulose samples with different levels of grafting were characterized by differential scanning calorimetry (DSC) and the thermogravimetric analysis (TGA). The CaCO3 filler makes the pulp of bagasse thermally more stable. The grafting of MMA onto the bagasse or the wood pulps improves their thermal stability. This is not the case for wood grafted with poly(AN). The thermal stability of the grafted and ungrafted samples varies after a few weight percent has been lost. The glass transition temperature (Tg) of the copolymers have been measured and they are in good agreement with the calculated data. © 1993 John Wiley & Sons, Inc.

Preparation of fibrous adsorbents containing amidoxime groups by radiation‐induced grafting and application to uranium recovery from sea water

AbstractPolypropylene fibers and polyethylene hollow fibers were used as trunk polymers and were irradiated by electron beams with a dose of 200 kGy under N2 atmosphere. Grafting of acrylonitrile to those irradiated fibers was carried out at 40°C for different periods of time. The degree of grafting was determined as a function of time. The fibrous adsorbents containing amidoxime groups were prepared by the reaction of acrylonitrile‐grafted polymers with 3% hydroxylamine in a methanol–water mixture (1 : 1). Distribution of copper ions complexed with amidoxime groups at various adsorption times was obtained by electron‐probe X‐ray microanalysis. The amidoxime groups are homogeneously distributed in the cross section of fibrous adsorbents. The fibrous adsorbents based upon polypropylene fiber of 40 μm showed a remarkable kinetic behavior for Cu2+. Even after 15 min, the adsorption capacity was 2.32 mmol Cu2+ per gram of fiber. Also, the functionalization with hydroxylamine was carried out at different conditions to compare the adsorption characteristics of the resultant adsorbents. Despite having superficially different properties (elemental microanalysis, ion‐exchange capacities, adsorption capacity for UO), the polypropylene‐based fibrous adsorbents showed similar adsorption properties for uranium from sea water. The adsorption tests proved the performance of the polypropylene‐based fibrous adsorbents as a promising material for uranium recovery from sea water. In addition, uranium uptake of fibrous adsorbents increased in proportion to the volume of sea water. © 1993 John Wiley & Sons, Inc.

Effects of Reaction Medium on Grafting of Acrylonitrile Onto Sodium Salt of Partially Carboxymethylated Amylose

AbstractThe grafting of acrylonitrile (AN) onto sodium salt of partially carboxymethylated amylose (Na‐PCMA) using ceric ammonium nitrate (CAN) as an initiator has been studied in water/solvent mixtures. The solvents used include methanol, ethanol, propanol, butanol, acetone and carbon tetrachloride. The results have been discussed. The effect of reaction medium on the molecular weight of grafted PAN has also been studied. The chain transfer constants (Cs) for solvents like methanol, ethanol, propanol, butanol, acetone and carbon tetrachloride have been evaluated at 30°C by the help of Mayo's equation.

Thermal Decomposition of Cellulose Grafted with Acrylonitrile in a Homogeneous System

The homogeneous grafting of acrylonitrile (AN) onto cellulose was carried out in a dimethyl sulfoxide/paraformaldehyde solvent system. The thermal decomposition behavior of cellulose, polyacrylonitrile (PAN), AN grafted products, and cellulose/PAN blends was investigated. The grafted products were regarded as polymer blends containing graft copolymers because cellulose and PAN homopolymer (homo-PAN) fractions were not extracted from them. The decomposition temperatures of the grafted products with higher PAN graft polymer(graft-PAN) content decreased remarkably than those of cellulose and PAN. The decomposition thermograms of the grafted products with higher homo-PAN content and those of the blended samples were similar to the superimposed ones of those of cellulose and PAN. The microphase separated structures of the grafted products with higher graft-PAN content were fine. Moreover, the water accessibility of these samples was larger than that of cellulose. It was suggested that the thermal decomposition measurements are effective for estimating compatibility in cellulose/PAN blends.

Chemically induced graft copolymerization of acrylonitrile on to hydrolysed wood pulp

AbstractGrafting of acrylonitrile on to hydrocellulose derived from the hydrolysis of wood pulp has been studied using cerie ammonium nitrate as initiator. The graft yield, the grafting efficiency and the total conversion were found to be highly affected by the various parameters studied including the initiator and monomer concentrations, the polymerization time and temperature. Moreover, the effect of the extent of grafting on the moisture regain property of the hydrolysed wood pulp has been also investigated.

Saponification of Graft Copolymers of Sodium Salt of Partially Carboxymethylated Amylose and Its Water Absorbency

AbstractThe grafting of acrylonitrile (AN) onto amylose and sodium salt of partially carboxymethylated amylose samples having different degrees of substitution has been carried out using ceric ammonium nitrate (CAN) as redox initiator. The saponification of all the PAN‐containing graft copolymers has been carried out by methanol precipitate method. The water retention values of all the graft copolymers have been measured and compared. The results have been discussed.

Investigation of phase morphology of incompatible polyethylene/nylon 6 blends containing EPDM-based functionalized compatibilizers

Graft copolymer and graft terpolymer were prepared by solution grafting of maleic anhydride (MAH) or acrylonitrile (AN) alone and mixture of MAH and AN on to ethylene–propylene–diene terpolymer (EPDM) using benzoyl peroxide (BPO) as an initiator. The resulting EPDM-g-MAH, EPDM-g-AN and EPDM-g-(MAH-co-AN) have been used to obtain a binary blend of Nylon 6/functionalized EPDM and a ternary blend of polyethylene/Nylon 6/functionalized EPDM by melt blending. The effects of the nature and the amount of the grafted species on the phase morphology, crystallization behavior and mechanical properties of the blends were characterized through scanning electron microscopy, optical microscopy, infrared spectroscopy and using a dynamic mechanical analyzer. From the morphological study, it can clearly be seen that the presence of the functionalized EPDMs in these blends resulted in an improvement of the dispersion degree in incompatible polyethylene/Nylon 6 blends.

Grafting of acrylonitrile to poly(styrene‐co‐acrylonitrile) by transformation with a titanium catalyst

Poly(styrene-co-acrylonitrile)-graft-polyacrylonitrile graft copolymers were prepared using a mixed (free-radical Vanionic) mechanism technique. For this purpose, poly(styrene-co-acrylo-nitrile) random copolymers which contain different amounts of acrylonitrile segments were regarded as saturated high-molecular-weight nitrile compounds and were allowed to react with tetrakis(dimethyl amino)titanium. By this treatment pendant nitrile groups were transformed to organometallic active sites. These active groups lead to the polymerization of acrylonitrile via an anionic insertion process. Polyacrylonitrile grafts were grown on the poly(styrene-co-acrylonitrile) backbone.

Grafting of acrylonitrile and methyl methacrylate to poly-2-vinylpyridine, activated by tris- π-allylchromium

Graft copolymers of poly-2-vinylpyridine-acrylonitrile and poly-2-vinylpyridine-MMA are synthesized with the aid of poly-2-vinylpyridine, activated by tris- π-allylchromium. The products obtained are characterized by different physical methods.

Modification of polyvinyltrimethylsilane by radiation grafting of acrylic monomers

The kinetics of the process of radiation grafting polymerization of acrylonitrile, acrolein and ethyl acrylate to aymmetrical membranes and homogeneous films from polyvinyltrimethylsilane was investigated. It was found that the grafting of acrylonitrile and ethylacrylate to films from polyvinyltrimethylsilane (radiation dose 400–800 rad/s) is diffusion controlld, whereas the grafting of acrolein is not limited by the diffusion of monomer to the active centres generated in the bulk of the polymeric support. The penetration and diffusion of several gases through polyvinyltrimethylsilane films, containing up to 40% of the graft component, was studied. The results obtained are discussed within the model of gas penetration in two-phase systems.

Optimum preparation conditions of amidoxime hollow fiber synthesized by radiation‐induced grafting

AbstractThe preparation process of amidoxime hollow fiber consists of three steps: (1) radiation‐induced graft polymerization of acrylonitrile (AN) onto porous hollow fiber (AN grafting), (2) chemical conversion of the cyano group into an amidoxime group (amidoximation), and (3) conditioning of the hollow fiber with alkaline solution (alkaline treatment). Systematic optimization of this preparation process was found to improve the adsorption rate. For the AN‐grafted hollow fiber having 130% degree of grafting, the optimum reaction was 1 h each for amidoximation and alkaline treatment, respectively. Also the change in the structure of the amidoxime hollow fiber with alkaline treatment was discussed based on measurements of water content, swelling and pore volume distribution, and observation of morphology of cross section by SEM.

Radiation‐initiated graft copolymerization of individual monomer and comonomer onto polyethylene and polytetrafluoroethylene films

AbstractPreparation and some properties of the graft copolymers obtained by radiation‐induced graft polymerization of methacrylic acid (MAA) and (acrylonitrile/MAA) comonomer onto polyethylene and polytetrafluoroethylene films, were investigated. The effect of reaction conditions, solvent, monomer, and inhibitor concentration, comonomer composition, and comonomer concentration, on the graft copolymerization process was studied. The grafting process was enhanced in the presence of comonomer (AN/MAA) as compared with individual grafting of MAA or acrylonitrile (AN). The optimum comonomer composition, at which the highest grafting yield was obtained, was found to be (80/20) wt % of (AN/MAA) comonomer. The graft copolymerization of (AN/MAA) comonomer was enhanced in presence of AN due to its higher polarity strength. The electrical and swelling properties of the graft copolymers were greatly affected by the contents of PAN and PMAA graft chains. Mechanical properties of the graft copolymers were significantly changed with the grafting yield.

Cationic Graft Polymerization of 2-Oxazolines on Poly(vinyl alcohol) Derivatives

Abstract The graft polymerization of various monomers onto PVA has been studied by radical polymerization mechanism. Successful grafting of acrylonitrile (AN), acrylamide (AAm), acrylic acid, methyl methacrylate, and vinyl acetate was reported by using chemical (Minoet al., 1959; Ide, 1961; Maskimov et al., 1965) and radiation (Misra et al., 1987) methods. On the other hand, less attention has been paid to ionic graft polymerization. Sasson and Zilkha reported on grafting formaldehyde onto potassium-metallated PVA (Sasson and Zilkha, 1969). Galin studied grafting of AN and propane sulfone onto sodium-metallated PVA (Galin, 1971). We used the same anionic system for the polymerization of AAm (Ikeda and Suzuki, 1980).

Features of the kinetics of radiation-induced graft post-polymerization of acrylonitrile onto capron fibres from the gaseous phase

The effects of temperature, vapour pressure, and irradiation dose of the rate of graft polymerization of acrylonitrile onto γ-irradiated capron fibres is studied. it is established that the concentration of growing grafted chains is much higher than the concentration of capron radicals. The observed relations can be explained on the assumption that the initiation rate is small and is determined by the segmental mobility of the matrix, while the growing polyacrylonitrile chains rapidly disappear. The values of the k g/√k t ratio for grafting of acrylonitrile at 20 and 80°C are determined. These are an order of magnitude higher than in the polymerization of acrylonitrile in solution.