Radiation-induced graft polymerization of 4-vinyl pyridine to styrene–butadiene–styrene triblock copolymer

The radiation-induced graft polymerization of 4-vinyl pyridine to styrene–butadiene–styrene triblock copolymer (SBS) was investigated. Relations between the rate of grafting and the dose rate when SBS was irradiated in 4-vinyl pyridine–methanol solution, and between the rate of grafting and 4-vinyl pyridine concentration of 4-vinyl pyridine–methanol solution have been investigated. An experiment that had been carried out on SBS immersed in various 4-vinyl pyridine concentration of 4-vinyl pyridine–methanol solutions showed that the extent of swelling of SBS by the various 4-vinyl pyridine–methanol solutions increased with increasing 4-vinyl pyridine concentration. The largest rate was found at 20 vol % 4-vinyl pyridine–methanol solution. The rate was smaller at the volume percent of 4-vinyl pyridine higher or lower than 20 vol %. On the assumption that the theory of homogeneous homopolymerization could be applied to this grafting reaction, the value of k_p²/k_t was obtained, where k_p and k_t are the propagation and termination constant, respectively. The value of k_p²/k_t greatly decreased with increasing adsorbed concentration of vinyl pyridine–methanol solution. This decrease of k_p²/k_t was explained by the fact that 4-vinyl pyridine and methanol absorbed in SBS acted as a plasticizer which increased the molecular motion of the polymer. The solvent effect on the graft polymerization was also investigated. The result was explained by solubility parameter. When the chosen solvent had better solubility with the polymer, the degree of grafting was smaller. That was connected with the extent of the polymer chain mobility.     

Synthesis and characterization of dextrin‐grafted polypropylene

We carried out the graft copolymerization of the water‐soluble natural polymer dextrin onto preirradiated polypropylene (PP) in an aqueous medium using benzoyl peroxide (BPO) as the radical initiator. PP was irradiated by γ rays from a Co⁶⁰ source at a constant dose rate of 3.40 kGy/h to introduce hydroperoxide linkages, which served as the sites for grafting. The graft copolymerization was studied as a function of different reaction parameters, and the maximum percentage grafting (P_g; 55%) of dextrin onto PP was obtained at optimum conditions of [BPO] = 5.165 × 10⁻² mol/L, temperature = 60°C in 120 min with 15 mL of water. Different grafting parameters, such as the percentage apparent grafting, percentage grafting, and percentage true grafting have been evaluated. The graft copolymers were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. Swelling studies were carried out in pure, binary, ternary, and quaternary solvent systems composed of water, ethanol (EtOH), dimethyl sulfoxide (DMSO), and N,N‐dimethylformamide (DMF) at different ratios. The maximum swelling percentage PP‐g‐dextrin (both composite and true graft) was observed in pure DMSO and DMF followed by EtOH and water. Water‐retention studies of PP and PP‐g‐dextrin (both composite and true graft) were investigated at different time periods, temperatures, and pH values. The maximum percentage water retention of PP‐g‐dextrin (composite, 124%) was observed at 8 h and 50°C in a neutral medium (pH 7). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

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.     

The grafting of methyl methacrylate onto cotton by tri-n-butylborane

Methyl Methacrylate was grafted onto cotton by tri-n-butylborane in the presence of water. No graft was obtained in organic solvents, i.e., in the absence of water. The percentage of grafting increased with increases in reaction time, cotton amount, and initiator concentration. Pretreatment of cotton with pyridine also enhanced the percentage of grafting. Glycidyl methacrylate and ethyl acrylate were grafted onto cotton by tri-n-butylborane, while no grafting occurred when vinyl acetate and 4-vinyl pyridine were used. Usual radical initiators, such as azobisisobutyronitrile and benzoyl peroxide/dimethyl-p-toluidine, were not effective under the same conditions.     

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.     

Graft copolymerization of 4-vinylpyridine and methyl acrylate onto polyethylene film by radiochemical method

Graft copolymerization of 4-vinyl pyridine (4-VP) and methyl acrylate (MA) onto polyethylene (PE) was studied in aqueous medium in air by the mutual irradiation method. The percentage of grafting was determined as a function of the (i) total dose, (ii) monomer concentration, and (iii) amount of water. The effect of different alcohols such as methanol, ethanol, isopropyl alcohol, butanol, and pentanol on the percentage of grafting of 4-VP and MA was studied. The effects of different amines on the percentage of grafting of 4-VP were also studied. The graft copolymers were characterized by IR spectroscopy and thermal analysis and by identifying the isolated polymer from the grafted film. Grafted PE film was tested for permeability behavior and was found to be permeable to a 0.5% aqueous sodium chloride solution. A plausible mechanism is suggested to explain the grafting of 4-VP and MA onto PE film. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 599–610, 1998     

Radiation‐induced graft copolymerization of 2‐vinylpyridine and styrene onto isotactic polypropylene fiber

Isotactic polypropylene fiber (IPP) was graft‐copolymerized using 2‐vinyl pyridine (2‐VP) and styrene (sty) as the monomers by the mutual irradiation method in air. The percentage of grafting was determined as a function of various reaction parameters and it was found that the maximum grafting of 2‐VP (114%) and sty (76%) was obtained at an optimum dose of 1.08 × 10⁴ and 0.64 × 10⁴ Gy using 1.8 × 10⁻² mol of 2‐VP and 4.3 × 10⁻² mol of sty, respectively. The graft copolymers were characterized by differential scanning calorimetric analysis and isolation of the grafted chains from the grafted iPP samples. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2959–2969, 1999     

Chemical modification of jute fibers. II: A study on the Fe2+/H2O2-initiated graft copolymerization of methyl methacrylate,acrylonitrile, and acrylamide onto jute fibers

The study of graft copolymerization of methyl methacrylate, acrylonitrile, and acrylamide onto both defatted and bleached jute fibers using the ferrous ammonium sulfate / H₂O₂ redox initiator system has been made. To determine the optimum conditions of grafting, the effects of concentrations of ferrous ammonium sulfate, monomer, H₂O₂; time and temperature on percentage of graft yield have been studied. Acrylamide was found to graft onto the fiber only at a fixed ferrous ammonium ion concentration (5 × 10^?4M). Kinetic studies showed that the rates of grafting follow the second-order mechanism. The activation energies of the reactions were found to be 3.351 and 2.53 kcal/mol in the methyl methacrylate and acrylonitrile systems, respectively. The grafted fibers have been characterized by thermogravimetric analysis, IR spectroscopy, and XRD studies.     

A modified model and algorithm for flow‐enhanced crystallization—Application to fiber spinning

The graft copolymerization of acrylamide (AAm) monomer onto polyethylene‐coated polypropylene (PE‐co‐PP) nonwoven fabric was carried out by the mutual irradiation method. The general peculiarities of the grafting have been studied by gravimetric, scanning electron microscope (SEM), mechanical properties, and Fourier transform infrared (FTIR) methods. The influence of absorbed dose, dose rate, as well as the monomer concentration on the degree of grafting has been determined. Metal ions uptake of Cu²⁺, Co²⁺, Ni²⁺ by the grafted fabrics was evaluated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3240–3245, 2006     

Designing a support for borohydride through grafting onto crosslinked polyvinylpyrrolidone

Crosslinked polyvinylpyrrolidone (PVPy) was grafted with polyvinylpyridine by irradiating the polymer beads in air from a Co⁶⁰ γ-radiation source and then heating with 4-vinylpyridine (4-VP) in water. The percentage of grafting was studied as a function of various reaction parameters and was determined from the increase in weight of PVPy and from the estimation of pyridine rings introduced into the polymer. PVPy-g-poly(4-VP) was treated with sodium in ethanol, which is known to reduce pyridine into piperidine together with small amounts of 1,2,5,6-tetrahydropyridine. On methylation with dimethyl sulfate and alkali, these are further converted into N,N-dimethylpiperidinium groups. The dimethylpiperidinium graft was used to support borohydride ions and the graft copolymer was shown to cleanly reduce several carbonyl compounds to the corresponding alcohols. © 1996 John Wiley & Sons, Inc.     

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     

Grafting onto wool. XXVIII. Effects of acids on gamma-radiation induced graft copolymerization of ethylmethacrylate onto wool fiber

Graft copolymerization of ethylmethacrylate (EMA) onto Himachali wool fiber has been investigated in aqueous medium by mutual gamma irradiation from a Co⁶⁰ source in air and in nitrogen atmosphere. Percentage of grafting has been evaluated as a function of (i) total dose, (ii) concentration of monomer, and (iii) effect of concentration of different acids such as hydrochloric acid, sulfuric acid, nitric acid, perchloric acid, and acetic acid. Maximum percentage of grafting has been obtained in the presence of sulfuric acid. Following reactivity order of different acids towards grafting has been observed: H₂SO₄ > HCI > HNO₃ > HCIO₄ > CH₃COOH. A plausible mechanism to explain the effect of acids on percentage of grafting of EMA has been suggested.     

Study of thermal and dyeing behavior of isotactic polypropylene fiber graft copolymerized with acrylate monomers using preirradiation method

In an attempt to modify isotactic polypropylene (IPP) fiber, grafting of acrylate monomers such as methyl acrylate (MA) and ethyl acrylate (EA) onto IPP has been carried out by preirradiation method in aqueous medium. Percentage of grafting has been determined as a function of various reaction parameters. Rate of grafting (R_g) and induction period (I_p) have been evaluated as a function of total initial monomer concentration. Methyl acrylate was found to be more reactive than ethyl acrylate toward grafting. Thermogravimetric analysis (TGA) indicates that the thermal stability of polypropylene fiber is significantly improved upon grafting. While polypropylene fiber could not be dyed by crystal violet, the grafted fiber was dyed with crystal violet, and the dye uptake has been quantitatively determined by spectrometric method. © 1994 John Wiley & Sons, Inc.     

Grafting onto wool. XXIII. Graft copolymerization of methyl methacrylate by use of chromium acetyl acetonate–perchloric acid system: Effect of tertiary butyl hydroperoxide

Methyl methacrylate (MMA) has been graft copolymerized onto Himachali wool in an aqueous medium by using chromium acetyl acetonate in the presence of perchloric acid at 45, 55, 65, and 75°C for various reaction periods. Percentage of grafting has been determined as functions of various reaction variables. Tertiary butyl hydroperoxide (TBHP) was found to influence grafting of MMA. Rate of grafting (R_p) and induction period (I_p) of MMA towards graft copolymerization were determined as function of total initial monomer concentrations. In the absence of TBHP, R_p does not change markedly with the increase in monomer concentration. When the graft copolymerization was carried out in the presence of TBHP, an increase in R_p and a decrease in I_p were observed.     

Homogeneous Photoinouced Graft Copolymerization of Acrylamide onto Abs Copolymers in the Presence of 4-Acetyldiphenyl as Photosensitizer.: 1. Influence of Butadiene Content in Abs Copolymers

Photoinduced graft copolymerization of acrylamide (AM) onto two types of acrylonitrile-butadiene-styrene (ABS) copolymers was extensively investigated in homogeneous media. The grafting process was conducted in chloroform in presence of 4-acetyldi-phenyl (4-AD). Ultraviolet (UV) irradiation was used in the range of 310 to 460 nm. The UV spectrum of 4-AD has sλ_max at 285 nm and shows n-π^? transitions. The grafting parameters, such as weight conversion, grafting percentage, and grafting efficiency, were determined as a function of the irradiation time and the concentrations of monomer, initiator, and substrate. A reverse effect was observed between the grafting percentage and the butadiene content in ABS copolymers. The rates of graft copolymerization of AM onto the two types of ABS copolymers were determined. A Trommsdorf effect was observed in certain systems. The IR spectrum of ABS-g-AM graft copolymer shows the appearance of a new peak at 1685 cm^-1 that declares the presence of poly-acrylamide-grafted chains onto the ABS copolymer backbone. A probable copolymerization mechanism was proposed.     

Graft copolymerization of methacrylic acid onto isotactic polypropylene by radiochemical methods

Graft copolymerization of methacrylic acid onto isotactic polypropylene has been studied in water–methanol medium using γ-rays as the source of initiation. Graft copolymerization has been conducted by (1) mutual irradiation, (2) preirradiation, and (3) double irradiation methods. All of the reaction parameters that seem to influence grafting have been studied, and the optimum conditions leading to maximum percentage of grafting have been evaluated. A plausible mechanism for radiation-induced grafting of methacrylic acid onto polypropylene has been suggested, and the results have been explained on the basis of the proposed mechanism. A comparative study of graft copolymerization by different radiation methods has been made, and it was observed that the preirradiation method affords the best results. Evidence of grafting has been obtained from differential scanning calorimetric analysis and the dyeing behavior of the grafted material. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 143–152, 1998     

Synthesis and characterization of N‐vinyl pyrrolidone and cellulosics based functional graft copolymers for use as metal ions and iodine sorbents

To develop cost effective and eco friendly polymeric materials for enrichment and separation technologies, 1‐vinyl‐2‐pyrrolidone (N‐VP) was graft copolymerized onto cellulose, extracted from pine needles. Optimum conditions have been evaluated for the grafting of N‐VP onto cellulose and at these conditions it was also grafted onto cellulose phosphate, hydroxypropyl cellulose, cyanoethyl cellulose, and deoxyhydrazino cellulose. At the optimum grafting conditions for N‐VP, it was also cografted with maleic anhydride. Kinetics of radiochemical graft copolymerization has been studied and evaluation of the polymerization and grafting parameters as percent grafting, percent grafting efficiency, rate of polymerization, homopolymerization, and graft copolymerization have been evaluated. Graft copolymers have been characterized by elemental analysis, FTIR, and swelling studies. An attempt has been made to study sorption of some metal ions such as Fe²⁺ and Cu²⁺ and iodine on select graft copolymers to investigate selectivity in metal ion sorption and iodine sorption as a function of structural aspects of the functionalized graft copolymers to find their end uses in separation and enrichment technologies. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 373–382, 2005     

SBS/VP homograft membrane for oxygen enrichment

The grafting of 4-vinyl pyridine (VP) onto styrene-butadiene-styrene triblock copolymers (SBS) by homografting irradiation with dissolved oxygen was studied. Homograft membranes of various degree of grafting were prepared from a casting solution of grafted copolymer in benzene. The mechanical properties of membranes, gas permeability, and the effect of operating temperature on gas permeation were investigated. The degree of grafting of 8.4% was the largest at an irradiation time of about 15.5 h. It was smaller at both shorter and longer duration because of the interference of dissolved oxygen. It was found that the tensile strength and elongation of SBS-g-VP were similar to those of SBS. The stress relaxation of SBS-g-VP was slower than that of SBS, and this might be due to the formation of rigid microphase separation domain of poly(4-vinyl pyridine), which acted as permanent crosslinking points to reduce the stress relaxation. Using the properties of high flux of SBS and high O₂/N₂ selectivity of poly(4-vinyl pyridine), the performance of gas permeation of 4-vinyl pyridine homografted SBS membrane was studied. The selectivity of SBS-g-VP membrane increased with increasing degree of grafting. However, it was done at the expense of a decrease in the gas permeability. When the operating temperature of gas permeation increased, the permeability of oxygen and nitrogen increased, and the O₂/N₂ permeability ratio decreased. The activation energy (Ep) for gas permeation through different degree of grafting of SBS-g-VP membrane (obtained by the Arrhenius law) increased with increasing degree of grafting. For ungrafted SBS membrane, Ep was 5.5 kcal/mol for oxygen and 7.2 kcal/mol for nitrogen. For 8.4% grafting degree SBS-g-VP membrane, Ep for oxygen and nitrogen, were 6.5 and 8.1 kcal/mol, respectively.     

Kinetics of swelling assisted grafting of 4-vinyl pyridine onto poly(ethylene terephthalate) fibers using a benzoyl peroxide initiator

Summary Poly(ethylene terephthalate) (PET) fibers were grafted with 4-vinyl pyridine (4-VP) using benzoyl peroxide (Bz₂O₂) as initiator. Fibers were swelled in dichloroethane (DCE) for 2 h at 90 °C to promote the incorporation and the subsequent polymerization of 4-VP onto PET fibers. Variations of graft yield with time, temperature, initiator and monomer concentrations were investigated. Percent grafting was enhanced significantly by increasing Bz₂O₂ concentration up to 2 × 1 0 ^-3 mol/L and then decreased upon further increase in initiator concentration. Increasing the 4-VP concentration up to 0.6 mol/L improves the graft yield significantly. The optimum temperature and polymerization time was found to be 50 °C and 2 h respectively. Further changes in properties of grafted PET fibers such as moisture absorption capacity and intrinsic viscosity were determined. Grafted PET fibers were charactarized by thermogravimetric analysis and scanning electron microscopy (SEM). Molar mass of the grafted chains was also determined.     

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