Graft copolymerization of acrylonitrile and its binary mixture with 4-vinyl pyridine onto isotactic polypropylene powder by preirradiation method

Graft copolymerization of acrylonitrile (AN) and its binary mixture with 4-vinyl pyridine (4-VP) onto isotactic polypropylene powder in aqueous medium, using γ-rays as an initiator, was studied. Optimum conditions for affording maximum percentage of grafting were evaluated. Rate of grafting (Rg) of AN and binary mixture (4-VP + AN) was determined as a function of total initial monomer concentrations. The graft copolymers were characterized by IR spectroscopy and thermogravimetric analysis. © 1995 John Wiley & Sons, Inc.     

Radiochemical graft copolymerization of methacrylonitrile and binary mixture of methacrylonitrile with 4-vinylpyridine onto isotactic polypropylene fiber

Graft copolymerization of methacrylonitrile (MAN) and its binary mixture with 4-vinylpyridine (4-VP) onto isotactic polypropylene (IPP) fiber has been studied in aqueous medium by the preirradiation method. Optimum conditions for obtaining the maximum percentage of grafting have been evaluated. Rate of grafting (Rg) has been determined as a function of total initial monomer concentration. The graft copolymers are characterized by IR spectroscopy, by thermogravimetric analysis, and by isolating the polymer from the graft copolymer. The effect of MAN, an acceptor monomer, on percentage of grafting of 4-VP, a donor monomer, has been discussed in the light of the mechanism proposed for grafting by the radiochemical method. © 1994 John Wiley & Sons, Inc.     

Modification of Tefzel film through graft copolymerization

The graft copolymerization of styrene (st) and methacrylonitrile (MAN) onto Tefzel film in aqueous media by the preirradiation method has been studied. In order to follow the effect of preswelling of the backbone polymer, grafting was attempted onto preirradiated Tefzel film and monomer preswollen, preirradiated Tefzel film. Optimum conditions pertaining to maximum percentage of grafting of st and MAN have been evaluated. Grafting onto preswollen, preirradiated Tefzel film displayed better results. The effect of different alcohols of increasing chain length on the percentage of grafting of st and MAN was also studied. Graft copolymerization of st showed an increase, while grafting with MAN exhibited a decrease, in the percentage of grafting in the presence of alcohols as compared to that obtained in the aqueous medium. Characterization of the graft copolymers was made by IR and thermogravimetric studies. Tefzel‐graft‐polystyrene showed improved thermal stability while the MAN grafted onto preswollen, preirradiated Tefzel film produced graft copolymer with poor thermal stability. Copyright © 2004 Society of Chemical Industry     

Graft copolymerization of 4-vinyl pyridine onto isotactic polypropylene hydroperoxide by mutual irradiation method

An attempt has been made to graft copolymerize 4-vinyl pyridine onto isotactic polypropylene hydroperoxide by mutual irradiation method in an aqueous medium. Polypropylene hydroperoxide has been prepared by irradiating recrystallized polypropylene beads from a Co⁶⁰ source in the presence of air. The resulting polypropylene hydroperoxide beads have been used as the backbone polymer and grafting of 4-vinyl pyridine has been studied as a function of various reaction parameters. Optimum conditions for maximum percentage of grafting have been evaluated. Rate of grafting (R_g) has been determined as a function of preirradiation dose and initial monomer concentration. Water has been found to affect percentage of grafting. The graft copolymers have been characterized by spectroscopic method and isolation of the grafted poly(4-VP) from the graft copolymer. A plausible mechanism is proposed to explain the mutual grafting of 4-vinyl pyridine onto polypropylene hydroperoxide. © 1993 John Wiley & Sons, Inc.     

LDPE膜单面辐射接枝丙烯酸的动力学特征

试验表明，黄瓜雌性系回交后代，具有多代的回交优势。杂种一代优势率为１８．９％－３２．５％，ＨＦ２优势为７．３％－４６．１％，ＨＦ３优势率为１１．４％－２０．１％，ＨＦ４的优势率为９．３％－１５．７％，表现较强的多代杂种优势。回交后代的抗病性，随着回交代数的增加，有不断增强的趋势，从而为开展黄瓜多代杂种优势利用，提供了依据。     

Synthesis and Characterization of Carboxymethyl Chitosan Grafted Methacrylic Acid Initiated by Ceric Ammonium Nitrate

O-carboxymethyl chitosan (CMCH) was prepared and characterized by FTIR spectroscopy and X-ray diffraction. Grafting of methacrylic acid (MA) onto CMCH using ceric ammonium nitrate (CAN) as an initiator was carried out under nitrogen atmosphere in aqueous solution. Evidence of grafting was confirmed by comparison of FTIR spectra of CMCH and the grafted copolymer as well as scanning electron micrograph (SEM) and X-ray diffraction of the products. The effects of concentration of CAN, MA, reaction time and temperature on graft copolymerization were studied by determining the grafting percentage and grafting efficiency. Keeping other conditions constant, the optimum grafting conditions were obtained as follows: CMCH = 2 gm, CAN = 0.2 M and MAA = 0.581 mol/L, reaction temperature = 40°C and reaction time = 4.5 hr.     

Graft polymerization of 4-vinylpyridine onto cellulosic fibres by the ceric ion method,I. The reaction time effect

A study was made of the time affecting the ceric ion induced grafting of 4-vinylpyridine (4-VP) onto partially carboxymethylated cotton (PCMC) having different degrees of substitution (D.S.). For comparison the same monomer was grafted onto cotton and mercerized cotton. The grafting parameters of these copolymerization reactions were determined. The graft yields for PCMC were significantly higher than those for unmodified cotton and mercerized cotton. The degree of crystallinity of the graft copolymers and of the unmodified cotton and PCMC samples was determined by the X-ray method. The crystallinity index decreased with the presence of grafted polymer. The reaction time effect of the grafting of 2-VP on cotton was also studied.     

Thermosensitive surface properties of polyethylene film with poly(N-isopropylacrylamide) chains prepared by corona discharge induced grafting

Polyethylene (PE) film was treated by corona discharge and then grafted with N-isopropylacrylamide (NIPAAm) for modification of the surface. The grafted amount was determined by gravimetry and the surface morphology was observed by using a scanning electron microscope. The surface analysis was carried out with a x-ray photoelectron spectroscopy and electron probe microanalysis. It was clarified that grafting was limited surface and there was no change of the surface morphology after grafting. The water absorption at various temperature under the absolute humidity (11.4 g/cm³) and the leakage of electrostatic charge from PE film were measured. PolyNIPAAm that was introduced onto PE surface has hydrophilic-hydrophobic transition properties at the 32°C in the atmospheric condition. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1773–1779, 1998     

Preparation and characterization of teflon–FEP films grafted with acrylic acid by radiochemical method

In an attempt to prepare permselective membrane, grafting of acrylic acid (AAc) onto Teflon–fluorinated ethylene-propylene (FEP) film was studied in aqueous medium by the preirradiation method in air. Grafting was carried out by heating a mixture of AAc, water, and preirradiated Teflon–FEP film in air at 93°C for definite time periods. Percentage ofgrafting was determined as a function of total dose, monomer concentration, reaction time, and amount of water. Maximum percentage of grafting (60.17%) was obtained at a total dose of 4.8 Mrad using 0.07M [AAc]. Evidence of grafting was obtained from the physical appearance and swelling behavior of the grafted film in polar solvents. Infrared spectroscopic and thermal analysis of the grafted film provided additional evidence for grafting. A plausible mechanism for grafting of AAc onto preirradiated Teflon–FEP film in air has been proposed. © 1995 John Wiley & Sons, Inc.     

Graft copolymerization of polyethylene glycol methacrylate onto polyethylene film and its blood compatibility

In an attempt to produce surfaces that show low levels of adsorption of protein and adhesion of platelets, different molecular weights of polyethylene glycol methacrylate (PEG‐MA) were grafted onto polyethylene film by a preirradiation grafting process. The extent of grafting was found to be dependent on the storage condition of the irradiated polyethylene film, the preirradiated dose, reaction time and temperature, molecular weight of PEG‐MA, and the type of solvent. The grafting yield was found to decrease rapidly with storage time for irradiated polyethylene film stored at room temperature. On the other hand, the grafting yield in the irradiated polyethylene stored at −130°C remained nearly constant up to 20 days after irradiation. The grafting yield decreased with an increased PEG‐MA molecular weight. Human plasma protein was adsorbed onto control and PEG‐MA‐grafted polyethylene film surfaces, and the relative adsorbed amount of proteins on the surfaces was evaluated by electron spectroscopy for chemical analysis. The adsorbed protein and platelet adhesion on the polyethylene film surface decreased rapidly with the grafting yield. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 631–641, 1999     

Radiation grafting of N,N-dimethylaminoethylmethacrylate and 4-vinylpyridine onto polypropylene by the one- and two-step methods

Summary Radiation grafting of N,N-dimethylaminoethylmethacrylate (DMAEMA) and 4-vinylpyridine (4-VP) from the 50% monomers solutions in toluene and dichloroethane onto polypropylene (PP) films was carried by their mutual γ-irradiation (one-step method). In the two-step method, the grafting of DMAEMA or 4-VP from their solutions in toluene was performed onto PP modified preliminary with the other polymer (poly4-VP or polyDMAEMA). It has been found that chemical structure of PP modified with the first grafted polymer affected the efficiency of the other monomer grafting by the second step. Received: 30 April 2001/Revised version: 21 October 2001/Accepted: 28 November 2001     

Graft copolymerization of methyl acrylate onto silk sericin initiated by tert‐butyl hydroperoxide

A novel redox system, tert‐butyl hydroperoxide (TBHP)–silk sericin (SS), was used to initiate the graft copolymerization of methyl acrylate (MA) onto silk sericin in an aqueous medium. The graft copolymer, consisting of nanoparticles with a fine core–shell structure, was characterized using Fourier transfer infrared spectroscopy. The effects of the concentrations of MA and TBHP, reaction temperature and time on the grafting parameters of the copolymerization were studied in detail. In terms of grafting percentage and grafting efficiency, the optimum reaction conditions were obtained as follows: [MA] = 0.465 mol L^?1, [TBHP] = 3.884 × 10^?4 mol L^?1, T = 80 °C, t = 150 min. Transmission electron microscopy images of the particles showed a core–shell morphology, where poly(methyl acrylate) cores were covered with SS shells. A possible initiation mechanism is proposed. Copyright © 2006 Society of Chemical Industry     

Effect of L(-)threonine, 5-hydroxytryptophane,and 5-hydroxytryptamine on the ceric-ion-initiated grafting of methyl acrylate onto cellulose

In order to study the effect of some radio protecting agents (RPA) such as L (-)threonine, 5-hydroxytryptophane (5-HT), and 5-hydroxytryptamine on ceric-ion-initiated grafting onto cellulose, attempts have been made to graft copolymerize methyl acrylate (MA) in aqueous medium in the presence and absence of RPA. Percentage of grafting has been determined as functions of concentration of (i) ceric ion, (ii) H₂SO₄, (iii) monomer, (iv) RPA, (v) reaction time, and (vi) reaction temperature. Maximum grafting percentage was obtained at [MA] = 5.53 × 10^–2mol/L within 180 min at 45°C in the absence of RPA. Grafting reactions were found to be suppressed in the presence of different RPAs. A plausible mechanism is suggested to explain the observed behavior of RPAs in grafting reactions. The graft copolymers have been characterized by IR spectroscopic and thermogravimetric methods. © 1993 John Wiley & Sons, Inc.     

Radiochemical grafting of methacrylonitrile and its binary mixture with methyl acrylate onto gelatin

Methacrylonitrile (MAN) has been graft copolymerized individually and as a binary mixture with methyl acrylate (MA) onto gelatin by a simultaneous irradiation method. Percentage grafting has been studied as a function of total radiation dose, monomer concentration, amount of water and water–methanol system. It was found that addition of MA increased the grafting efficiency of MAN. A plausible explanation has been suggested to account for the trends in the results © 1998 SCI.     

Graft Copolymerization of Methyl Acrylate onto Oil Palm Empty Fruit Bunch (OPEFB) Fiber

Graft copolymerization of methyl acrylate (MA) onto OPEFB fiber has been successfully carried out using hydrogen peroxide and ferrous ammonium sulfate as initiators in an aqueous medium. The effects of reaction temperature, reaction period, and amount of monomer and initiators on the percentage of grafting were investigated. The results show that the percentage of grafting depends on reaction period and temperature as well as concentration of monomers and initiators. With 33.36 mmol of MA, the optimum percentage of grafting was obtained when the reaction was carried out using 6.00 mmol of H₂O₂ and 0.191 mmol of Fe²⁺ for 210 min at 75°C. The presence of the functional group in the grafted polymers was characterized by FTIR spectroscopy. Scanning electron microscopy was used to study the surface morphology. Thermogravimetric analysis indicated that the grafted OPEFB is thermally stable than the OPEFB     

PE氯化接枝St/AN共聚共混物研究

采用固相法对聚乙烯(PE)进行氯化接枝苯乙烯/丙烯腈(St/AN)单体,制得了改性氯化聚乙烯(CPE)材料。探讨了氯化反应温度、氯含量、引发剂过氧化苯甲酰(BPO)用量和单体配比对聚合物力学性能的影响,实验中还对PE接枝了不同单体,结果表明,采用二段温度(70℃,120℃)法,氯质量分数为35%,BPO加入质量为0.24g,m(St)/m(AN)为1:1时,可制得力学性能较好的CPE材料。极性单体MA、AN及St的加入提高了CPE材料的拉伸强度。     

Co(III) acetylacetonate-complex-initiated grafting of N-vinyl pyrrolidone on cellulose in aqueous media

The graft copolymerization of N-vinyl pyrrolidone (N-VP) onto cellulose was carried out with a cobalt acetylacetonate complex Co(acac)₃ as an initiator under a nitrogen atmosphere at 50 ± 0.1°C. The graft yield percentage (%G) obtained as a function of the concentrations of N-VP and Co(acac)₃ and the temperature was used to calculate various other grafting parameters and the grafting rate dependence on the concentrations of monomer, Co(acac)₃ and reaction temperature. The energy of activation (ΔE_a) for the grafting of N-VP onto cellulose was 22.7 kJ/mol within 40–60°C. The molecular weights of the grafted chains and homopolymers were determined viscometrically with a Ubbelohde-type viscometer. Graft yield (%G) in the presence of various additives such as sodium lauryl sulfate, cetyltrimethylammonium bromide, and methanol was studied, and the results are suitably explained. On the basis of the experimental results, a reaction scheme for graft copolymerization is proposed, and a kinetic rate expression is presented. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2286–2296, 2001     

4-Vinylpyridine and 2-hydroxyethylmethacrylate monomer mixture graft copolymerization onto poly(ethylene terephthalate) fibers using benzoyl peroxide

Summary Poly(ethylene terephthalate) (PET) fibers were grafted with 4-vinyl pyridine (4-VP) and 2-hydroxyethylmethacrylate (HEMA) using benzoyl peroxide (Bz₂O₂) as initiator in aqueous media. PET fibers were swelled in dichloroethane (DCE) for 2 h at 90 °C to promote the incorporation and the subsequent polymerization of 4-VP/HEMA onto PET fibers. Variations of graft yield with time, temperature, initiator concentration and monomer mixture ratio were investigated. The optimum initiator concentration was found to be 8×10^-3 mol/L. The maximum graft yield was obtained 280%. The optimum temperature and polymerization time was found to be 85 °C and 100 min. respectively. The rate of grafting was found to be proportional of the 1.5 and 0.3 powers of 4-VP/HEMA and Bz₂O₂ concentrations, respectively. The grafted PET fibers were characterized by thermo gravimetric analysis and scanning electron microscopy (SEM). Further changes in properties of grafted PET fibers such as water absorption capacity, intrinsic viscosity and diameter were determined. The dye ability of the PET fibers increased with an increase in grafting with diazo and basic dyes.     

Grafting styrene onto a polyethylene surface: A model study of an interfacial reaction

A model reactor system was assembled to study surface grafting reactions which would occur at the polymer interface in in-situ blend compatibilization using a vector fluid. The vector fluid's purpose is to convey a reactive ingredient to a blend interface and induce copolymer formation. Polyethylene (PE) was chosen as the polymer substrate, styrene monomer and/or dimethyl phthalate (DMP) as the vector fluid, and a peroxide initiator as the reactive ingredient. The free radical surface grafting reaction of styrene onto the PE surface was studied at melt processing temperature with a factorial experimental design involving the factors of time, temperature, initiator type and initiator concentration. It was found that styrene monomer was grafted at the PE substrate surface, forming a layer of PE-g-PS graft copolymer which was observed with attenuated total reflection Fourier transform infrared spectroscopy. The results indicated that the grafting reactions occurred not only at the immediate surface (2–3 μm), but also beneath the PE surface (∼ 200 μm) due to the swelling of the PE by the styrene monomer. The reaction below the immediate surface could be significantly reduced by the presence of DMP, a nonsolvent of PE; but the surface reaction was not affected. Explanations for the reaction behavior of the two different vector fluids are proposed based on the experimental results. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 427–440, 1998     

Selective Solid Phase Extraction of Chromium(VI) using Silica Gel Immobilized 4-vinyl Pyridine/Cupric Ion Complex

Immobilization of 4-vinyl pyridine (4-VP) onto silica gel (SG) and its coordination with cupric ion (SG-4-VP→Cu²⁺) leading to a new solid phase extractor has been carried out by a simple chemical technique. Immobilization and coordination reactions are characterized by chemical, FTIR, UV, and thermo-gravimetric analysis. The role of cupric ion on Cr(VI) binding capacity of the synthesized organic-inorganic hybrid material has been elucidated. The silica gel immobilized 4-VP/Cu²⁺ complex (hybrid material) is tested for selective extraction and pre-concentration of Cr(VI) from aqueous solution. The Cr(VI) binding behavior of the synthesized material is studied at different pH, time, and temperature of the medium in both competitive and non-competitive conditions.