Graft copolymerization of N-vinylpyrrolidone onto gelatin

The graft copolymerization of N-vinylpyrrolidone (VP) onto gelatin in aqueous medium, with α,α′-azobisisobutylonitrile as initiator, has been studied. The effects of various reaction parameters such as temperature, reaction time, as well as the concentrations of initiator, monomer, and gelatin on the percentage of grafting and grafting efficiency were also studied. The chain-transfer constant of isopropanol in this system was calculated. Finally, the grafted samples were analyzed with IR, DSC, TEM, and SEM measurements. © 1995 John Wiley & Sons, Inc.     

Graft copolymerization of acrylonitrile onto bagasse and wood pulps

Graft copolymerization of acrylonitrile onto bagasse and wood pulps has been studied using ceric ammonium nitrate as initiator. The effect of order of reactants addition on grafting was examined: three methods were studied. Addition of the pulp to a mixture of initiator and monomer (method A) resulted in more efficient grafting than the other two methods. The reaction produced more grafting at 50°C than at 30°C or at 40°C. The results showed that the monomer and initiator concentrations are the major factors influencing the grafting rate of acrylonitrile. Increasing the acrylonitrile or initiator concentration was accompanied by a substantial increase in graft yields. Increasing the initiator concentration is more effective on polymerization rate than the increase in monomer concentration. The extent of grafting of this monomer can best be controlled by reaction time. Water swelling of pulps significantly affected the grafting rate of acrylonitrile as well as the ceric consumption during grafting. The reactivity of bagasse pulp towards grafting of acrylonitrile is higher than that of wood pulp due to a more open structure of cellulose in bagasse pulp as well as the presence of some lignin which accelerates grafting. Ceric consumption during grafting depends on the nature of the pulp as well as the monomer and initiator concentrations, time, temperature, and the method of grafting. More Ce(IV) is consumed during grafting than during oxidation of the pulps under identical reaction conditions, due to homopolymer formation which accompanied grafting. The ceric consumption by bagasse during grafting or oxidation is somewhat greater than that consumed by wood pulp under similar reaction conditions.     

Graft copolymerization of styrene and acrylonitrile onto EPDM

Acrylonitrile–EPDM–styrene (AES) graft copolymers were synthesized by solution graft polymerization of styrene (St) and acrylonitrile (AN) onto EPDM in an n‐hexane/benzene solvent with benzoyl peroxide (BPO) as an initiator. The structure changes were studied by an FTIR spectrophotometer. The grafting parameters were calculated gravimetrically. The influence of the polymerization conditions, such as the reaction time, concentration of the initiator, EPDM content, and weight ratio of St/AN, on the structure of the products was investigated. It was found that a proper initiator concentration and EPDM content will give a high grafting ratio of the AES resin. The thermal property of the copolymer was studied using programmed thermogravimetric analysis (TGA). The results showed that the copolymer has a better heat‐resistant property than that of ABS, especially for the initial decomposition temperature (T_in) and the maximum weight loss rate temperature (T_max). Also, the mechanism of the graft reaction was discussed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 428–432, 2002     

Graft copolymerization of hydroxyethyl methacrylate onto chitosan

Chitosan is a polysaccharide derived from chitin, which is commonly found in shellfish waste materials. The present work is concerned with the graft copolymerization of 2-hydroxyethylmethacrylate (HEMA) onto chitosan using thiocarbonation–potassium bromate for redox initiation. The combined effects of the principal reaction variables for the grafting reaction were studied systematically. This grafting reaction was studied with respect to percentages of graft yield (%G.Y.), homopolymer (%H.P.), and total conversion (%T.C.). A tentative polymerization mechanism is proposed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 683–702, 2001     

Grafting of vinyl monomers onto natural rubber,II. Graft copolymerization of methyl methacrylate onto natural rubber using tetravalent ceric ions

The use of tetravalent ceric ions to initiate graft-copolymerization of methyl methacrylate onto natural rubber (NR) has been investigated. The rate of grafting has been determined by varying the concentration of monomer and cerium(IV), the temperature and the solvents. The graft yield increases with increasing monomer concentration up to 1.877 M, with further increase of the monomer, the graft yield decreases. The percentage of grafting increases with increasing cerium(IV) concentration up to 0.035 M, thereafter it decreases. With increasing temperature the graft yield increases. The effect of CuSO₄ on the rate of grafting has also been investigated. A plausible mechanism has been suggested and the kinetic rate expressions have been derived.     

三元乙丙橡胶溶液接枝丙烯腈

对三元乙丙橡胶在二甲苯中与丙烯腈的接枝共聚进行了研究,结果表明AIBN可以有效引发接枝共聚,并且正交实验发现单体用量、引发剂浓度和反应温度均对接枝率有重要影响,条件适当接枝率可达15％以上。实验证明,接枝共聚物对丁腈橡胶／三元乙丙橡胶并用具有明显的增容作用。     

Graft copolymerization of methacrylates onto wool fibers

Grafting of butyl (BuMA), decyl (DeMA), and octadecyl methacrylate (ODeMA) onto reduced wool was carried out by using K₂S₂O₈ or K₂S₂O₈–LiBr redox system as initiator. The influence of the monomer and monomer concentration, temperature, and duration of the reaction on the percentage of grafting was studied. Evidence of grafting was provided by scanning electron microscopy, size exclusion chromatography, and infrared spectroscopy.     

Graft copolymerization of butyl acrylate onto pullulan using manganic pyrophosphate as initiator

The graft copolymerization of butyl acrylate onto pullulan using manganic pyrophosphate as initiator in aqueous medium was studied. The effects of concentration of initiator, monomer, pullulan, and sulfuric acid on the percentage of grafting, the grafting, efficiency, as well as the rate of graft copolymerization were investigated. The rate equation was derived and a suitable reaction mechanism was proposed. Finally, the grafted samples were characterized by IR spectral measurement.     

Grafting vinyl monomers onto silk fibers. II. Graft copolymerization of methyl methacrylate onto silk by hexavalent chromium ion

The feasibility of chromium(VI) to induce graft polymerization of methyl methacrylate onto silk was investigated. The rate of grafting was determined by varying monomer concentration, chromium(VI) concentration, temperature, acidity of the medium, nature of the silk, reaction medium, and redox system. The graft yield increased with increasing monomer concentration up to 0.65M, and with further increase of monomer the graft yield decreased. The graft yield increased with increasing chromium(VI) concentration. The grafting is considerably influenced by chemical modification of silk prior to grafting. The graft yield is influenced by thiourea concentration, decreasing with increasing thiourea concentration. The effect of certain inorganic salts and anionic surfactants on the rate of grafting was investigated.     

Graft copolymerization of methyl methacrylate onto cellulosic biofibers

In this article, we have used the potassium persulfate to initiate the graft copolymerization of methyl methacrylate onto cellulosic biofibers in aqueous medium. Different reaction parameters, such as reaction time, initiator molar ratio, monomer concentration, amount of solvent, and reaction temperature, were optimized to get the maximum percentage of grafting (50.93%). The graft copolymers thus formed were characterized by Fourier transform infrared, scanning electron microscopy, X‐ray diffraction, and thermogravimetric, differential thermal analysis, and derivative thermogravimetric techniques. A mechanism is proposed to explain the generation of radicals and the initiation of graft copolymerization reactions. On grafting, percentage crystallinity decreases with reduction in its stiffness and hardness. The effect of grafting percentage on the physicochemical properties of raw as well as grafted fibers has also been investigated. The graft copolymers have been found to be more moisture resistant and also showed better chemical and thermal resistance. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Graft copolymerization of acrylamide onto carboxymethylcellulose with the xanthate method

Acrylamide was grafted to an xanthate mixture of carboxymethylcellulose with a sodium bisulfate/ammonium persulfate redox initiator system in water, sodium hydroxide, potassium hydroxide, and dioxane at 40, 50, 60, 70, and 80°C during a reaction period of 2 h. The grafted polymer and homopolymer were isolated with diethyl ether from the reaction mixture, dried, and weighed. The grafted polymer was characterized with IR and mass spectrometry methods, and the microscopic morphology was detected with electron scanning microscopy. The graft level percentage distinctly increased with the use of sodium hydroxide, potassium hydroxide, and dioxane over that of a reaction carried out completely in an aqueous medium. Also, the graft level decreased as the reaction temperature increased. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 271–278, 2004     

Photo-induced graft copolymerization. III. Graft copolymerization of methyl methacrylate onto cellulose using peroxydiphosphate as photoinitiator

Photo-induced graft copolymerization of methyl methacrylate onto cellulose was investigated using peroxydiphosphate ion as the photoinitiator. The percentage graft yield increases with increasing both the monomer and initiator concentration. The reaction was carried out at three different temperatures, and the overall activation energy was computed. The kinetic data and other evidence indicate that the overall polymerization takes place by a radical mechanism. A suitable kinetic scheme has been suggested.     

Radiation induced graft copolymerization V. Graft copolymerization of methyl acrylate onto nylon-6 fiber

The radiation induced graft copolymerization of methylacrylate onto nylon-6 fiber at room temperature and in nitrogen medium was investigated. The effects of monomer, dose rate, inhibitor etc. on the graft yield have been investigated. The effect of solvents on the rate of grafting was studied from which the chain-transfer constant (C_s) of the solvent has been evaluated. Addition of certain inorganic salts was found to act as scavengers. The value of G_b, the number of branches per 100 eV of energy absorbed in the substrate polymer, was calculated. The density, moisture regain, alkali solubility, dyeability and thermal properties of the grafted nylon-6 fiber have been evaluated.     

Radiation-Induced graft copolymerization,I. Graft copolymerization of methyl methacrylate onto nylon-6

The radiation-induced graft copolymerization of methyl methacrylate onto nylon fibers was investigated at room temperature. The homopolymer was separated by soxhlet extraction. The graft yield increases with increase of dose rate from 0.1768 to 0.7072 Mrad. The percentage of grafting increase with increasing monomer concentration. Addition of copper sulphate and a non-ionic surfactant, sodium lauryl sulphate, supresses the formation of homopolymer. The value of G_b, the number of branches per 100 eV of energy absorbed in the substrate polymer, and the value of α, the fraction of substrate polymer grafted, have been computed. A kinetic scheme has been suggested.     

Grafting vinyl monomers onto polyester fibers. VI. Graft copolymerization of methyl methacrylate onto PET fibers using tetravalent cerium as initiator

The graft copolymerization of methyl methacrylate onto polyester fibers (PET) was investigated using tetravalent cerium as the initiator. The rate of grafting was found to increase progressively with the initiator and monomer concentrations up to 2.5 × 10^?2M and 70.41 × 10^?2M, respectively. The reaction was found to be catalysed by acid up to 15.0 × 10^?2M. The graft yield increased by increasing temperature. The effect of addition of some solvents and thiourea on the rate of grafting was also investigated. A suitable kinetic scheme has been pictured, and rate equations have been derived.     

Graft copolymerization of acrylonitrile onto hemicellulose using ceric ammonium nitrate

The ability of ceric ammonium nitrate to induce graft copolymerization of acrylonitrile onto hemicellulose was investigated. The graft yield depends on monomer and initiator concentrations as well as reaction time and temperature. Chemical analysis of the reaction product of hemicellulose and acrylonitrile in the presence of ceric ammonium nitrate revealed that the ceric ammonium nitrate acted as initiator for polymerization of acrylonitrile and as oxidizing agent for hemicellulose. Proof for grafting of hemicellulose was provided through IR analysis.     

Graft copolymerization of acrylonitrile onto starch using potassium permanganate as initiator

The ability of potassium permanganate to induce graft copolymerization of acrylonitrile (AN) onto starch was investigated. The graft yield depends on monomer and initiator concentrations as well as reaction time and temperature. Chemical analysis of the reaction product of starch and (AN) in presence of potassium permanganate revealed that the latter acted as initiator for polymerization of AN and as oxidizing agent for starch. Proof for grafting was provided through infrared analysis and solubility properties of the reaction product.     

Graft copolymerization of acrylamide–methylacrylate comonomers onto cellulose using ceric ammonium nitrate

The graft copolymerization of acrylamide–methylacrylate comonomers was carried out using ceric ammonium nitrate as initiator in the presence of nitric acid at 25 ± 1°C. The effects of feed molarity, feed composition, reaction time, and temperature on graft yield (%G) and other grafting parameters were investigated. The determination of rate of ceric (IV) ions disappearance as a function of feed molarity and reaction time was useful in the determination of the rate of ceric (IV) ions consumption during graft copolymerization. The graft yield (%G) in the presence of acrylamide increases because of the synergistic effect of acrylamide comonomer. The composition of the grafted chains (F_AAm) varies on varying the feed composition and reaction temperature but is almost constant during feed molarity variation. The Mayo and Lewis method was used to determine the reactivity ratios of acrylamide (r₁) and methylacrylate (r₂), which are 0.65 and 1.07, respectively. The product of reactivity ratio (r₁ r₂) is less then unity; hence, an alternate arrangement of comonomer blocks in the grafted copolymer chain is proposed. The rate of graft copolymerization of comonomers onto cellulose is second power to the concentration of comonomers and square root to the concentration of ceric ammonium nitrate. Suitable reaction steps for graft copolymerization of comonomers onto cellulose are proposed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2631–2642, 2002     

Graft copolymerization of benzyl methacrylate onto wool fibers

Benzyl methacrylate (BzMA) was graft copolymerized onto wool fibers by using ammonium peroxydisulphate as the initiator. Grafted samples with different polymer add ons (from 7 to 180%) were obtained by varying the monomer concentration in the reaction system. Following grafting with BzMA, the X-ray diffraction peak at 20.2° slightly moved towards higher spacing values. Birefringence decreased, indicating a lower degree of molecular orientation of grafted wool fibers. The equilibrium regain values of grafted wool decreased with increasing add on. Tensile strength increased in the range 45–77% add on, while elongation at break decreased. Differential scanning calorimetry (DSC) and thermogravimetry (TG) measurements showed a higher thermal stability for grafted wool. Following grafting, the drop of dynamic storage modulus (E′) shifted to a lower temperature. Accordingly, the intensity of the loss modulus (E′) peak decreased, indicating that the thermally induced molecular motion was enhanced by grafting. Thermomechanical analysis (TMA) confirmed the increase in chain mobility for the grafted wool fibers. Above 35–40% add on, the presence of homopolymer on the surface of the wool fibers was identified by scanning electron microscopy. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 343–350, 1997