Radiation Graft Polymerization Research Articles

海水ウラン捕集のコスト評価と実用化に向けての技術課題

The cost of uranium recovered from seawater was estimated to extract the technical problems in the practical application of the fibrous amidoxime adsorbent synthesized by radiation graftpolymerization. Each cost of the adsorbent production, the dipping in seawater for uranium absorption, and the uranium elution from the adsorbent was estimated in three different mooring systems of a buoy, floating body, and chain binding system. The recovery cost was estimated to be 5-10 times of that from mining uranium. More than 80% of the total cost was occupied by the cost for marine equipment for mooring the adsorbents in seawater, which is owing to a weight of metal cage for adsorbents. Thus, the cost can be reduced to half by the reduction of the equipment weight to 1/4. The improvement of adsorbent ability is research subjects in the future also, since the cost directly depends on the adsorbent performance.

Modification of poly(vinyltrimethylsilane) by radiation-induced graft polymerization

The modification of polyvinyltrimethylsilane (PVTMS) has been carried out using the radiation-induced graft polymerization. PVTMS is applied as a basis for gas-separating membranes. Acrylonitrile, acrolein, ethyl acrylate, acrylic acid and acrylamide were used as monomers. The grafting was performed both from vapour and liquid phase of monomers and their solutions by the direct radiation method. Some kinetic regularities of radiation graft polymerization of monomers and the character of distribution of grafted polymers along the thickness of PVTMS films were studied. It was shown that grafting improves the chemical resistance, the selective permeability of gases and some mechanical properties of PVTMS films.

Some modification on radiation graft polymerization of N-vinyl-2-pyrrolidone onto low density polyethylene with α,β-unsaturated nitrile

Abstract N -Vinyl-2-pyrrolidone (NVP) was grafted onto low density polyethylene (LDPE) films using γ -radiation by the direct method. The effect of grafting conditions such as inhibitor and monomer concentrations on the grafting yield was investigated. The homopolymerization of NVP was reduced to a minimum using ferric chloride solution and the suitable concentration of the inhibitor was found to be 0.008 wt%. The grafted polymer was modified using carbonitriles ( 2a – e ). The swelling behaviour increases with the degree of grafting. It was observed that the swelling behaviour of the modified grafted films with α -cyano- β -(2-thienyl)crotononitrile was an improvement on that of the grafted one. The modification process for the grafted polymer was confirmed by IR spectrophotometry. The biological activity of the grafted films and the modified one with α -cyano- β -(2-thienyl)crotononitrile was studied. The higher the degree of grafting the higher the carbonitrile reacted. The results suggest that the biological activity of the modified grafted films was higher than that for the grafted one, under the same conditions. An improvement of hydrophilic grafted membrane by modification with some carbonitrile compounds showed great promise in some practical applications.

Adsorption of plasma proteins to DMAA hydrogels obtained by ionizing radiation and its relationship with blood compatibility

The interaction of plasma proteins such as albumin, γ-globulin, and fibrinogen with the surface of graft copolymers DMAA-G-PTFE, DMAA-G-PETFE, and DMAA-G-PE obtained by radiation graft polymerization was studied. The adsorption of serum proteins was affected by the hydrophilicity of the graft copolymers. Increased albumin adsorption and decreased fibrinogen and γ-globulin adsorption with increasing grafting levels was shown. A certain range of degrees of grafting showed an improved blood compatibility of the polymeric surfaces due to the existence of a hydrophilic/hydrophobic balance on the polymers. The results suggest that the DMAA-G-PTFE, DMAA-G-PETFE, and DMAA-G-PE graft copolymers can be used as biomaterials for long-term use in cardiovascular systems.

Surface-modified hydrophilic membranes in membrane distillation

The porosity and the hydrophobicity of membranes are two essential requirements for membrane distillation (MD) of aqueous solutions. So far, the hydrophobic porous membranes used in MD studies have been prepared from hydrophobic materials. In this work, hydrophilic cellulose acetate and cellulose nitrate membranes were modified into hydrophobic membranes by radiation grafting polymerization and plasma polymerization, and used in MD studies successfully. The results indicated that modified membranes with good performance in MD can be obtained if the modifying conditions are controlled appropriately. Especially plasma polymerization, in which many particular kinds of monomer could be polymerized onto the surface of porous materials, has become an efficient method to prepare hydrophobic porous membrane with high performance from hydrophilic membranes. It will stimulate the development and practical application of MD.

Use of radiation graft polymerization for synthesizing and modifying gas-separating membranes—review

The synthetic possibilities of the radiation graft polymerization method for synthesizing and modifying membranes and the functionalization of the materials of membrane technology are reviewed. Attention is focused on the problems of synthesis of gas-separating membranes. In this connection the review also touches on the problems of imparting hydrophilic and ion-exchange properties to membranes. The relationship between the sorption, diffusional and some other properties of membranes, the aspects of their structure and the conditions of conducting synthesis is analysed.

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.

Radiation chemical modification of rubbers on the basis of ethylene-propylene terpolymer and butadiene-styrene thermoelastoplastic

With the purpose of improving the operating characteristics of rubbers on the basis of ethylene-propylene terpolymer and butadiene-styrene thermoelastoplastic their modification by radiation graft polymerization of acrylic monomers (acrylonitrile, acrylic acid, glycidyl methacrylate, cyanoethyl methacrylate etc.) was carried out. The investigations performed made it possible to select monomers, whose grafting onto rubbers improves the adhesion properties and increases oil resistance of the latter. A continuous grafting process by the method of impregnation of rubber with monomer using a pilot plant with an electron accelerator was developed. The output of the pilot plant at a dose rate of 2.2 kGy/s is 4.2 t/year.

Radiation graft polymerization of acrylamide onto polyethylene

Radiation grafting to LDPE of acrylamide by the direct liquid phase method from solutions in water and acetone using the method of pre-irradiation from aqueous solutions and also from the vapour phase of the monomer has been carried out. The highest grafting values were given by the direct method for low dose rates and high concentrations of the monomer and also by the preirradiation method using sufficiently high absorbed doses. The molar masses of the polyacrylamide homopolymer have been determined.

Kinetic characteristics of radiation graft polymerization of vinylidene chloride from the gas phase onto polypropylene fibre

The kinetic characteristics of radiation graft polymerization of vinylidene chloride from the gas phase onto polypropylene fibre were studied. It was found that the rate of grafting, up to high conversion, obeys the additivity relation and is determined by the idependently proceeding reactions of vinylidene chloride graft polymerization to a polypropylene support and to the grafted polyvinylidene chloride generated in the process. The dependence of these rates on the radiation dose, temperature and monomer concentration was determined. With these data, the kinetic curves can be calculated for any kind of selected reaction conditions.

Interaction of proteins with the surface of polymers

The interaction of proteins such as humanγ-globulin with the surface of polymers was studied. The adsorption of theγ-globulin was affected by the hydrophilicity (degree of hydration) of the polymers, in which optimum hydrophilicity appeared to exist for the adsorption of theγ-globulin. This feature was also observed in the adsorption of theγ-globulin on copolymers having various hydrophilic properties. The surface of the polymers was modified by radiation graft polymerization and the addition of a surfactant, and its effect on the interaction with theγ-globulin was studied.

Preparation and reactivity of metal-containing monomers. Communication 2. Radiation graft polymerization of allyl alcohol complexed on polyethylene

1. A study of the postradiation graft polymerization of complexed allyl alcohol was carried out for the first time. Copolymers were obtained containing up to 2.4 mass % polyallyl alcohol and 2.4 mass % metal. 2. The grafting rate is constant for several hours and increases with an increase in the concentration of the complexing agent in the reaction mixture up to [CoCl2]:[AA] mole ratio equal to 1∶5.

Use of the method of radiation graft polymerization for modifying polyvinyltrimethyl silane gas separating membranes

The authors investigate the possibility of modifying homogeneous and asymmetrical membranes of polyvinyltrimethyl silane by the method of radiation graft polymerization of AN. Radiation grafting was carried out by combined irradiation of the polymer membranes and monomer in the vapour phase. It was found that with increase in the γ-radiation dose graft polymerization of acrylonitrile on asymmetrical membranes proceeds at a much faster rate than on homogeneous films. It was shown that modified polyvinyltrimethyl silane membranes possess raised stability to the action of hydrocarbons. Increase in the PAN content in the membranes lowers the gas permeability coefficient and raises the selectivity of separation of the He/N 2 gas pair.

Preparation and reactivity of metal-containing monomers. Communication 3. Radiation graft polymerization of Co(II), Ni(II), and Cu(II) acrylates on polyethylene

1. Graft polymerization of Co(II), Ni(II), and Cu(II) acrylates was carried out on polyethylene powder subjected to prior irradiation in the air and graft copolymers were obtained with up to 1.4 mass % metal content. 2. The graft polymerization of metal acrylates on polyethylene proceeds 10 times more slowly than in the case of acrylic acid with virtually the complete absence of thermal homopolymerization. The graft rate is independent of the concentration of the metal-containing monomer in the range from 1 to 10 mass %. 3. The graft polymerization of acrylates is initiated by radicals formed as a result of the decomposition of the hydroperoxide groups with subsequent predominantly bimolecular termination of the growing polymer chains in the case of Co(II) and Ni(II) acrylates and monomolecular termination in the case of Cu(II) acrylate. The effective activation energies for the graft polymerization reactions were determined.

Diffusion‐controlled reaction. VI. Radiation graft polymerization of styrene to polyethylene

AbstractThe radiation graft polymerization of styrene to polyethylene was studied under diffusion‐controlled conditions of radiation intensity I, monomer concentration M1, and polymer sample thickness L. The results of the present study together with previous work under diffusion‐free conditions verify our theoretical model for the diffusion‐controlled reaction. The grafting rate is inverse first order in L for diffusion‐controlled reaction and independent of L for diffusion‐free reaction. The order of dependence of grafting rate on radiation intensity for diffusion‐controlled reaction is one‐half that for diffusion‐free reaction. Diffusion control leads to a decrease in the order of dependence of grafting rate on monomer concentration. The decrease is greater than theoretically predicted; possible reasons for this effect are described.

Radiation graft polymerization of styrene to cellulose acetate‐butyrate

AbstractThe kinetics of radiation graft polymerization of styrene onto cellulose acetate‐butyrate is studied over a range of radiation intensities and monomer concentrations. The reaction is diffusion‐free under the experimental conditions as shown by the independence of the grafting rate on film thickness. The dependence of the grafting rate on monomer concentration increases from 3/2‐order to slightly greater than 5/2‐order with increasing radiation intensity. The dependence of the grafting rate on radiation intensity decreases from 1/2‐order to 0‐order with decreasing monomer concentration. Possible mechanisms for these results are discussed.

Radiation graft polymerization of solid monomers by vapor-phase method

Radiation graft polymerization proceeding in the sublimation vapors of solid monomers exhibits a peculiar feature differed from that of the ordinary liquid-phase graft polymerization, and also from that of the vapor-phase graft polymerization utilizing gaseous monomers or vapors of liquid monomers. In this experiment, polyethylene and poly(ethylene-co-vinyl acetate) films were irradiated with the γ-rays in the atmosphere of α,β-disubstituted ethylenic solid monomer such as maleimide, maleic anhydride, or acenaphthylene, or in that of the binary solid comonomers. Graft polymerization was characterized by little occluded homopolymer formation and high efficiency of grafting. When the monomer vapor was not sorbed into the polymer film, the reaction took place on the surface of film with the formation of fine granules of the grafted polymer. The oxygen gas coexisting with the monomer vapor did not inhibit the grafting reaction, but merely retarded it to the same extent as nitrogen. Thus the graft polymerization of unsorbed polar monomer as maleimide or maleic anhydride onto polyethylene was considered to proceed on the surface by a solid-state polymerization mechanism. When the monomer was sorbed and dispersed monomolecularly into the backbone polymer film, the grafting reaction seemed to proceed mainly in the inner part of the film. Grafting of copolymer took place when a film was exposed under γ-rays to a combined vapor of binary solid monomers chosen as an electron donor-acceptor combination, and in some cases nearly-alternating copolymer grafting was achieved even if one of the binary comonomers could not be sorbed into the film. The effects of the affinity of film to monomers on the rate of grafting and on the composition of grafted copolymer were also investigated by adopting poly(ethylene-co-vinyl acetate) films of various compositions and their surface-modified ones.

Diffusion‐controlled reaction. VI. Radiation graft polymerization of 4‐vinylpyridine to polyethylene

AbstractThe radiation‐initiated graft polymerization of 4‐vinylpyridine to high‐density polyethylene was studied over a wide range of reaction conditions of radiation intensity I, monomer concentration M1, and polymer film thickness L. The conditions included both diffusion‐free and diffusion‐controlled graft polymerizations. The results corroborate our previous theoretical predictions on the effect of I, M1, and L on the experimental grafting rate. The grafting rate is inverse first order in L for diffusion‐controlled reaction and independent of L for diffusion‐free reaction. The dependence of grafting rate on radiation intensity decreases from 1/2 to 1/4 order for diffusion‐controlled reaction. Diffusion control results in a decrease in the dependence of rate on monomer concentration. The observed decrease is somewhat greater than theoretically predicted.

Correlation between processes of radiation graft polymerization of acrylonitrile in materials and variation of physical and chemical properties

Grafting of acrylonitrile (AN) on high pressure polyethylene (PE) and other polymer films was carried out from liquid and gaseous phase and from benzene solution by direct γ-radiation and post-polymerization. Dose rate I varied from 35 to 240 rad/ /sec, the dose of irradiation Q irr from 0·1 to 10 Mrad and film thickness from 0·0035 to 0·26 cm. The macrokinetic mechanisms established were examined from the point of view of diffusion kinetics. In gaseous-phase grafting the ratio k/ k r = 5 × 10 4, which is evidence of the monomolecular mechanism of growing chain termination in polyacrylonitrile (PAN) and the heterophase mechanism of polymerization. The graft film is a colloidal system: PAN microphase “particles” are distributed in the matrix. A variation in molecular mobility of the matrix in a layer adjoining PAN micro-particles is indicated by a higher equilibrium concentration of AN in a PE film with an increase in the content of PAN and by a probable increase of the life time of matrix radicals. Together with mechanisms of diffusion kinetics this explains the mechanism of self-regulation of the extension and formation of graft structures on a micro- and macro-level: acceleration and deceleration of grafting and localization of grafting in the surface layer of films, which distinguishes qualitatively the grafting process from other methods of preparing colloidal polymer systems. Plasticization of PE using benzene eliminates structural and kinetic effects.

Monomer dependence of radiation graft polymerization. VI. Low‐density polyethylene–styrene

The results presented here are for reaction conditions in which the rate of monomer diffusion into the polyethylene does not limit the rate of graft polymerization. This was established by observing the reaction rate experimentally as independent of polymer film thickness for films 0.002 and 0.003 in. thick. Thus the graft polymerization rates for 100% styrene at 0.037 Mrad/hr are 0.128 and 0.121%/min, respectively, for film thicknesses of 0.002 and 0.003 in. It was earlier proven to obtain the order of dependence of rate on monomer it is necessary that the styrene concentration be varied without altering the internal microviscosity of the reaction system. This was accomplished by using benzene as a diluent for styrene. The extent of swelling (and therefore the internal microviscosity) of polyethylene by styrene--benzene solutions was experimentally observed to be 8.0% independent of composition. Furthermore, the composition of the styrene--benzene solution absorbed into the polyethylene films by refractive index measurements was experimentally analyzed. 3 figures.