Graft Polymerization Of Acrylonitrile Research Articles

A novel silane coupling agent with peroxy groups used as an initiator in the graft polymerization of AN or MMA on nano-TiO2

A novel peroxy group-containing silane coupling agent was synthesized and anchored on the surface of titanium dioxide nanoparticles (nano-TiO2) to form an immobilized-initiator-modified nano-TiO2 species. In this study, the kinetic parameters of the peroxy group-containing silane were tested and assessed using DSC. The pre-exponential factor (Ad) was 8.973 × 108 and the activation energy (Ea) was 80.736 kJ mol−1. Moreover, the empirical Arrhenius equation was determined to be ln Kd = − 80.736/RT + ln(8.973 × 108). To obtain continuous polymers, acrylonitrile (AN) and methyl methacrylate (MMA) were polymerized using the novel peroxy group-containing silane and FeSO4 as an initiator system. The number average molecular weights (Mn of PAN = 3×104 and Mn of PMMA = 1.4 × 105) and polydispersity indexes (PDI of PAN = 2.76 and PDI of PMMA = 1.65) were determined by GPC. It was suggested that the redox initiation system can generate highly reactive species on the surfaces of inorganic nanoparticles. The nano-TiO2-grafted polymers were successfully obtained.

Optimization of molar content of amidoxime and acrylic acid in UHMWPE fibers for improvement of seawater uranium adsorption capacity

Ultra-high molecular weight polyethylene (UHMWPE) fibrous adsorbents with different molar content of amidoxime (M AO) and acrylic acid (M AA) were prepared by graft polymerization of acrylonitrile (AN) and acrylic acid (AA), followed by amidoximation. Uranium adsorption experiments in both artificial and natural seawater were carried out to investigate the effect of M AO and M AA on the uranium adsorption capacity of UHMWPE fibrous adsorbents. Adsorption results showed that the UHMWPE fibrous adsorbent with M AO = 4.27 and M AA = 4.64 mmol/g-ads exhibited better uranium adsorption capacity in both artificial (7.01 mg-U/g-ads) and natural (0.77 mg-U/g-ads) seawater.

A new approach of synthesis and morphological control of poly(ethylene terephthalate)-g-polyacrylonitrile composite film with a porous surface

Poly(ethylene terephthalate)-g-polyacrylonitrile (PET-g-PAN) composite film with a porous surface was fabricated via gamma-ray-radiation-induced graft polymerization on PET film in an aqueous solution system. The original PET film was first irradiated by gamma ray in the aqueous solution of acrylic acid. Next, the graft polymerization of acrylonitrile (AN) was induced by gamma ray on the surface of the above modified PET film in an aqueous solution of AN. The prepared PET-g-PAN composite film has a smaller static water contact angle than the original PET film. The SEM and AFM images show that the grafted PAN layer on the surface of PET-g-PAN composite film is composed of closely-arranged spherical PAN microspheres with an average diameter of 30nm. The gaps between the PAN microspheres form fine pores (less than 30nm) on the surface. The gas barrier property of the PET-g-PAN composite film is much better than that of the original PET film. This work provides a facile and green method to prepare PET-g-PAN composite film with a controllable porous surface morphology by taking advantage of the radiation-induced graft polymerization technique in an aqueous solution system.

Studies on Preparation of Composite Chelating Material Poly(amidoxime)/SiO2 with Grafting-Type

Micron-sized silica gel particles were first surface-modified with a coupling agent, γ-methacryloylpropyl trimethoxysilane (MPS), so polymerizable double bonds were introduced onto the surfaces of silica gel particles. Then, acrylonitrile (AN) was graft polymerized on the surfaces of the modified particles in the manner of “grafting from”, resulting in the grafted particles PAN/SiO2. In succession, the grafted PAN was transformed into the grafted poly (amidoxime) (PAO) via aminoximation transformation reaction with hydroxylamine hydrochloride as a reaction reagent, and the composite chelating particles PAO/SiO2 with graft-type were obtained. In this work, the effects of main factors on the graft polymerization of AN and on the aminoximation transformation reaction were investigated in depth. At the same time, the chelating adsorption property of PAO/SiO2 particles for heavy metal ions and rare ions was preliminarily examined. The experiments results show that: (a) In graft polymerization, the reaction temperature and the used amount of initiator should be controlled to obtain the grafted particles with high grafting degree; (b) It is feasible to transform the grafted particles PAN/SiO2 into the functional particles PAO/SiO2 via aminoximation reaction, and the nitrile groups conversion can get up to 78%; (c) In aminoximation transformation reaction, the reaction temperature and the pH value of the medium should be selected as 70°C and pH=6-7, respectively. The experiment results also indicate that PAO/SiO2 particles possess a very strong chelating adsorption ability for heavy metal ions, Pb2+and Cu2+, and rare earth ions, Eu3+ and Sm3+, by right of the strong chelating action of amidoxime groups.

STUDIES ON GRAFTING POLY(AMIDOXIME) ON CROSSLINKED POLYVINYL ALCOHOL MICROSPHERES VIA GRAFT POLYMERIZATION-POLYMER REACTION METHOD

The graft polymerization of acrylonitrile on crosslinked polyvinyl alcohol(CPVA) microspheres was performed by using cerium ammonium sulfate as initiator,and grafted microspheres CPVA-g-PAN were prepared.Subsequently,the grafted PAN was converted into poly(amidoxime)(PAO) via amidoximation reaction with hydroxylamine hydrochloride as reagent,resulting in the functional microspheres CPVA-g-PAO.The chemical structure and physicochemistry characters of CPVA-g-PAO microspheres were adequately characterized by infrared spectrum(FTIR),scanning electron microscope(SEM) and determining zeta potential.The effects of main factors on the amidoximation transform reaction of the grafted PAN were studied with emphasis,and the adsorption property of the functional microspheres CPVA-g-PAO for some biomolecules was examined preliminarily with uric acid as a model biomolecule.The experimental results show that in the a midoximation transform reaction of nitrile groups,medium pH and reaction temperature are two main factors.For this system,the adequate pH value and temperature are 6 ～ 7 and 70℃.Under the fitting conditions,the conversion ratio of the nitrile group of the grafted PAN reaches 72% for 4 h.In a wider pH range,the zeta potential of the microspheres CPVA-g-PAO is a greater positive value.They exhibit strong adsorption ability for uric acid,a toxic endogenrsis molecule,and the adsorption capacity can get up to 95 mg /g.

Application of Some Starch Hydrogels for the Removal of Mercury(II) Ions from Aqueous Solutions

Three types of starch hydrogels were prepared via the graft polymerization of acrylonitrile, AN, onto maize starch using ceric ammonium nitrate, CAN, as the initiator, followed by saponification with sodium hydroxide. The prepared hydrogel samples were characterized by estimating their nitrogen and carboxy group contents, and by the application of FT-IR spectroscopy, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM); in addition, their water retention values, WRVs, were also determined. The feasibility of using these hydrogels to remove Hg(II) ions from aqueous solutions was examined. Factors affecting the adsorption of Hg(II) ions onto the starch hydrogels were studied, including the pH value of the solution, the contact time and the concentrations of the adsorbent and adsorbate. The present study has shown that the prepared hydrogels could be used effectively for the adsorption of Hg(II) ions from aqueous solutions. The adsorption data obtained obeyed the Langmuir and Freundlich isotherms. The adsorption of Hg(II) ions onto the starch hydrogels followed second-order kinetics. An examination was made of the mechanism for the adsorption of Hg(II) ions onto the starch hydrogels.

Vapour Phase Surface Graft Polymerization of Acrylonitrile onto Poly(ethylene terephthalate) Film

In this study the vapour phase surface graft polymerization of acrylonitrile (AN) onto poly(ethylene terephthalate) (PET) film was conducted with benzoyl peroxide (BPO) as an initiator. Effects of reaction time and quantity of BPO on the polymerization were investigated. With the prolongation of reaction time, the graft polymerization took place rapidly at first, then slowed down, and leveled off. With the increase of BPO, the graft yield increased, then remained unchanged, and lastly began to decrease. The surface topography structure of the grafted PET film was observed by SEM. Grafted PET film was characterised by FTIR spectra, SEM photographs and contact angle measurement.

New polysaccharide‐g‐polyacrylonitrile copolymers: synthesis and thermal characterization

AbstractVarious natural and modified polysaccharides (i.e. arabic gum, tragacanth gum, xanthan gum, sodium alginate, chitosan, sodium carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose) were modified using ceric‐initiated graft polymerization of acrylonitrile under inert atmosphere. Grafting was confirmed using spectral (FT‐IR) proofs. The grafting parameters were determined by conventional methods. Thermal characteristics of the homopolymer‐free copolymers were studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) under nitrogen atmosphere. The major thermal transitions as well as the activation energy of the major decomposition stages were investigated. The polyacrylonitrile (PAN)‐grafted polysaccharides were recognized to be thermally stable more than the corresponding non‐grafted substrates, although they begin to decompose at relatively lower temperatures than the non‐grafted counterparts. Copyright © 2003 John Wiley & Sons, Ltd.

Synthesis and Application of AN-g-EPDM and AA-g-EPDM as Compatibilizers for CR/EPDM and NBR/EPDM Rubber Blends

The graft polymerization of acrylonitrile (AN) or acrylic acid (AA) onto ethylene-propylene-diene terpolymer rubber (EPDM) was carried out in toluene, using dibenzoyl peroxide (BPO) as an initiator. The synthesized AN-g-EPDM and AA-g-EPDM were characterized by FT-IR spectroscopy and thermal gravimetric analysis (TGA). AN-g-EPDM and AA-g-EPDM were incorporated into chloroprene rubber (CR)/EPDM and butadiene acrylonitrile rubber (NBR)/EPDM blends. The compatibility of EPDM/CR and EPDM/NBR blends was examined with scanning electron microscope (SEM) and differential scanning calorimetry (DSC). The physico-mechanical properties of the vulcanizates were investigated after and before thermal aging. AN-g-EPDM and AA-g-EPDM improved the morphology of CR/EPDM and NBR/EPDM rubber blends. The mechanical properties illustrate that the compatibilized blends possessed good thermal stability.

Graft polymerization of acrylonitrile onto chemically modified bleached jute fibers

AbstractThe graft polymerization of acrylonitrile (AN) onto chemically modified bleached jute fibers has been studied using potassium peroxydisulfate‐ferrous ammonium sulfate redox initiating system. The effects of time of reaction, variation in concentration of monomer, peroxydisulfate, ferrous ammonium sulfate and sulfuric acid on graft yield have been studied. The effects of temperature, amount of jute fibers, some inorganic salts and organic solvents on graft yield have also been investigated. Grafted jute has been characterized by IR spectra. Grafting has improved the light fastness of jute dyed with Rhodamine B dye.

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.

Graft polymerization of acrylonitrile on acetate yarn under the action of gamma radiation

The graft polymerization of acrylonitrile from the vapor phase on acetate yarn under the action of γ-radiation has been studied. Conditions have been discovered for the preparation of modified acetate yarns with a degree of acrylonitrile grafting from 1.5 to 68.0 by wt. The possibility of increasing the resistance of acetate yarns to abrasion no less than 15-fold, with a simultaneous increase in breaking strength and retention of resistance to double bends, has been demonstrated.

Graft polymerization of acrylonitrile and methyl acrylate onto hemicellulose

AbstractGraft polymerizations of acrylonitrile onto both a commercial larchwood hemicellulose and a purified (low lignin) wheat straw hemicellulose could be initiated by ceric ammonium nitrate. The resulting hemicellulose‐g‐polyacrylonitrile (PAN) copolymers were fractionated by extraction at room temperature with dimethylformamide and dimethylsulfoxide. Fractions were characterized by determining both the wt % PAN in each polymer fraction and the molecular weight of grafted PAN. Saponification of the PAN component of hemicellulose‐g‐PAN gave a water‐dispersible graft copolymer with good thickening properties for water systems. An absorbent polymer, similar to the starch‐based absorbents (Super Slurpers), was produced when saponified hemicellulose‐g‐PAN was isolated by methanol precipitation and then dried. Larchwood hemicellulose was also graft‐polymerized with methyl acrylate using ceric ammonium nitrate initiation, and the hemicellulose‐g‐poly(methyl acrylate) was extrusion‐processed into a tough, leathery plastic. Although ceric ammonium nitrate could be used as an initiator for graft polymerizations onto low‐lignin hemicelluloses, it was inert with crude wheat straw hemicellulose containing 11% lignin. The ferrous sulfate–hydrogen peroxide redox system was used to initiate graft polymerizations onto this high‐lignin material, and properties of the resulting hemicellulose‐g‐poly(methyl acrylate) and saponified hemicellulose‐g‐PAN graft copolymers were evaluated.

Absorbent Polymers from Starch and Flour Through Graft Polymerization of Acrylonitrile and Comonomer Mixtures

AbstractPolyacrylonitrile (PAN)‐containing graft copolymers of corn starch were prepared from monomer mixtures and then saponified, and dried. Incorporation of selected comonomers lead to shorter saponification times and higher yields of adsorbent products. Substitution of flour for starch gave products which had a higher absorbency than saponified starch‐g‐PAN.

Latexes of starch-based graft polymers containing polymerized acrylonitrile

The scope of graft reactions to produce starch-based latexes was extended by graft polymerization of acrylonitrile (AN) onto gelatinized cationic starch possessing quaternary amine functionality and by graft terpolymerization of AN and t-butylaminoethyl methacrylate (TBAEM) onto gelatinized starch by cerium (IV) initiation at 25°C. Grafting onto starches containing highly basic quaternary amines gave polyacrylonitrile [poly(AN)] grafts having about one fourth the number-average molecular weight (Mn) (178,000–232,000) of those produced by grafting AN onto starches containing the less basic tertiary amine groups. Sonification at 20 KHz of graft polymerization reaction mixtures having up to 8% solids reduced viscosities from 400–3000 cP to 10–40 cP. Diameters of dried particles measured about 300–1500 A. Shaker-type agitation during grafting onto starch having quaternary amine groups produced poly(AN) chains with lower Mn values than those produced during blade stirrer-type agitation. Mn values of grafted poly(AN) decreased with increasing reaction time, degree of substitution of amine in the starch, gelation time of cationic starch at 95°C, and cerium (IV) concentration. AN was copolymerized with TBAEM at molar ratios of 14–85:1 in grafting onto gelatinized starch to yield copolymer side-chain grafts analyzing 8–52:1 of polymerized AN to TBAEM moieties.

The effect of grafted polyacrylonitrile on the physical heat resistance of polymethylmethacrylate films

Orientated films of polymethylmethacrylate and polybutylmethacrylate have been modified by graft polymerization of acrylonitrile (AN), under conditions ensuring preservation of the oriented structure of the matrix with uniform distribution of PAN through the cross section of the films. Even when the PAN content is low the matrices have the physico-chemical properties of network polymers, although they are not chemically crosslinked. Particles of PAN microphase function as active reinforcing agents.

Modification of polyethylene by anisodiametric grafted structures

High pressure polyethylene films (PE) have been modified by graft polymerization of acrylonitrile and vinylidenechloride and have then been subjected to orientational drawing at temperatures exceeding the melting point of PE and the glass transition temperatures of the grafted polymers. Under these conditions, oriented structures are found in PE and the grafted polymers: these form a “framework” which prevents the relaxation of the oriented PE structures and the reversion of the drawn specimens when heated in the free condition above the melting point of PE. The additive contributions of PE and the grafted structures of polyacrylonitrile and polyvinylidenechloride towards the strength and pliability of the films cause special features in the mechanical properties.

Alkali-metallation of 6-Nylon and Anionic Graft-copolymerization of the Metallated Nylon with Acrylonitrile

6-Nylon fibres were metallated with Li, Na or K metboxide in methanol and the metallated fibres were allowed to graft-copolymerize with acrylonitrile(AN) in tetrahydrofuran(THF) or dimethyl sulfoxide(DMSO) by the anionic mechanism.Concerining the metallation of the nylon, effects of reaction time, methoxide concentration and reaction temperature upon the alkali metal combination onto the nylon were investigated. The equilibrium amounts of alkali metals combined increased linearly with methoxide concentrations and in the order of Li g Na g K. The metallation reactions were endothermic and the reaction heats were in the order of Li g Na g K. The apparent activation energies obtained were in the order of Li l Na l K.Concerning the graft-polymerization of AN onto the metallated nylons, effects of AN concentration, reaction time, alkali metal combination and reaction temperature upon the graftings were investigated in either medium of THF-AN or DMSO-AN. The graftings increased linearly with AN concentration in THF-AN medium, while they gave a maximum at AN 40-60 vol % in DMSO-AN medium. Apparent activation energies obtained were in the order of Li l Na l K in THF-AN medium, while in the order of Li g Na K O in DMSO-AN medium.The number average molecular weights ( Mn ) of the graft chains were measured, which were formed in DMSO-AN and separated after hydrolysis of the copolymers with 6 N HCI. From the calculated molecular weights and the measured ones, the following results were obtained: in the case of Li, initiator efficiencies were O.7-l.5 and Mn of the graft chains were 7000-llOOO, while in the case of Na or K, initiator efficiencies were 3-5 and Mn of the graft chains 2000-4000, provided that the initiator efficiency was the ratio of the calculated number average molecular weight to the measured one.

6-ナイロンに対するアクリロニトリルのアニオングラフト重合

6-ナイロンに対するアクリロニトリルのアニオングラフト重合

Copolymers of modified starches with polyacrylonitrile

AbstractA study was made of the ceric ammonium nitrate‐initiated graft polymerization of acrylonitrile (AN) onto a number of modified starches that had been reduced in molecular weight by either acid, hypochlorite, or enzyme treatment. With highly soluble starches, much of the starting material was recovered as ungrafted carbohydrate, and the reaction product was largely dimethylformamide‐soluble polymer with a high polyacrylonitrile (PAN) content. The molecular weight of grafted PAN was lower when the modified starches existed as granules in water dispersion; however, heating (60°C) an aqueous slurry of an acid‐modified corn starch (with intact granules) before the reaction had relatively little effect on the composition of the copolymer. Decreasing the concentrations in water of modified starch and AN resulted in more frequent and lower molecular weight grafts of PAN. Aqueous methanol as a reaction medium for an acid‐modified starch with intact granules led to more frequent grafting of lower molecular weight PAN than when water alone was used. The number of grafted chains, however, was fewer than found with unmodified wheat starch under comparable conditions. A modified starch with the granule structure completely broken down gave no detectable reaction in aqueous methanol.