Grafting of ethyl acrylate onto gelatin in water-isopropanol medium

Graft copolymers were synthesized by grafting ethyl acrylate onto gelatin. The reaction was carried out in water-isopropanol medium (1:1 v/v). Reactions take place within 90 min. The resulting product is insoluble in solvents for the respective homopolymers. Presence of vinyl polymer was confirmed by IR spectra.     

Grafting of butyl acrylate onto gelatin in a water-isopropanol medium

Graft copolymerization of butyl acrylate onto gelatin using potassium persulphate initiator was studied in a water-isopropanol medium. The crude graft copolymers were soxhlet extracted with acetone to remove the loosely bound ungrafted homopolymer. The influence of a number of experimental factors such as effect of time, monomer concentration, initiator concentration, backbone concentration and temperature on the graft copolymerization of gelatin were investigated.     

Grafting of N,N′-methylenebisacrylamide onto silk fibers using the vanadylacetylacetonate complex in aqueous medium

The grafting of N,N′-methylenebisacrylamide (N,N′-MBA) onto mulberry silk fibers is reported using vanadylacetylacetonate (VO(acac)₂) complex under inert atmosphere at 50°C. The effect of various variables like, concentration of N,N′-MBA and VO(acac)_2, acidity of the medium and the surfactants on the percentage grafting have been investigated. The higher rate of radical formation has been explained due to the coordination of π-electrons of the N,N′-MBA with the metal chelate which has assisted in the cleavage of M? O bond to generate radical easily. A plausible mechanism for graft copolymerization involving cyclization of N,N′-MBA prior to the grafting has been proposed.     

Graft copolymerization of glycidylmethacrylate onto modified nylon‐6 fibers

The graft copolymerization of glycidylmethacrylate (GMA) onto modified nylon‐6 fibers containing polydiallyldimethylammonium chloride (PDADMAC) groups in the presence of (Cu ²⁺–K₂S₂O₈) as a redox initiating system was carried out, with very high extent and almost without homopolymer formation. The mechanism of the graft polymerization induced by this system was suggested. The rate of grafting was determined by varying the monomer, K₂S₂O₈, and cupric ion concentrations as well as the amount of PDADMAC. The kinetic investigation revealed that the rate of grafting (Rp) of GMA onto modified nylon‐6 fibers is proportional to [GMA]^1.83, [CuSO₄·5H₂O]^0.46, [PDADMAC]^0.4, and [K₂S₂O₈]^1.43. The overall activation energy was 134.7 kJ/mol. The fine structure and thermal properties of the grafted nylon‐6 fibers were investigated. investigated. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 613–618, 2006     

Grafting of water‐soluble sulfonated monomers onto functionalized fumed silica nanoparticles via surface‐initiated redox polymerization in aqueous medium

Sulfonated polymer/fumed silica hybrid nanoparticles were prepared via surface‐initiated free radical polymerization of 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid (PAMPS‐g‐FSN), styrene sulfonic acid sodium salt (PSSA‐g‐FSN) and vinyl sulfonic acid sodium salt (PVSA‐g‐FSN) from the surface of aminopropyl‐functionalized fumed silica nanoparticles (AFSNs) dispersed in aqueous medium. Cerium(IV) ammonium nitrate/nitric acid and sodium dodecyl sulfate were used as redox initiator and stabilizer respectively. AFSNs were prepared by covalently attaching 3‐aminopropyltriethoxysilane onto the surface of fumed silica nanoparticles. Sulfonated monomers (AMPS, SSA or VSA) were then grafted onto the AFSNs ultrasonically dispersed in water via redox initiation at 40 °C. Structure, thermal properties, particle size and morphology of the AFSNs and PAMPS‐g‐FSN, PSSA‐g‐FSN and PVSA‐g‐FSN hybrid nanoparticles were characterized by Fourier transform infrared spectroscopy, TGA, SEM, transmission electron microscopy (TEM) and dynamic light scattering (DLS). The results indicated that the sulfonated monomers were successfully grafted onto the fumed silica nanoparticles. Grafting amounts of the sulfonated polymers onto the fumed silica nanoparticle surface were estimated from TGA thermograms to be 59%, 13% and 29% for the PAMPS, PSSA and PVSA, respectively. From SEM, TEM and DLS analysis, polymer‐grafted fumed silica nanoparticles with an average diameter smaller than 70 nm and a (semi‐) spherical shape were observed. A significant bimodal particle size distribution was observed only for the PAMPS‐g‐FSN with average diameters of 39.6 nm (84.1% per number) and 106 nm (15.9% per number). The hydrophilic sulfonated polymer/grafted fumed silica obtained from the redox graft polymerization gave a stable colloidal dispersion in acidic aqueous medium. Copyright © 2012 Society of Chemical Industry     

Grafting of N,N′‐methylenebisacrylamide onto cellulose using Co(III)‐acetylacetonate complex in aqueous medium

The grafting of N,N′‐methylenebisacrylamide (N,N′‐MBA) onto cellulose is carried out using the cobaltacetylacetonate complex (Co(acac)₃) under nitrogen atmosphere at 40°C. The rate of graft copolymerization has been studied as a function of [N,N′‐MBA], [Co(acac)₃], and temperature. The activation energy of grafting is found to be 156.0 k J mol⁻¹ within the temperature range of 30–60°C. The effect of perchloric acid, methanol, and surfactants on graft yield has also been studied and results are suitably explained. The higher efficiency of the metal chelate in initiation of graft copolymerization has been assumed due to the coordination of the π electrons of the N,N′‐MBA with the metal chelate, which facilitated the formation of the radicals through homolytic cleavage of metal–oxygen bond of the cobalt acetylacetonate complex. On the basis of the results, a suitable kinetic scheme for graft copolymerization is presented and rate expression is derived. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 906–912, 2000     

Grafting of glycidyl methacrylate onto gelatin

Gelatin was graft copolymerized with poly(glycidyl methacrylate) using potassium peroxydisulfate in aqueous medium. Effect of temperature, time, initiator, monomer, and backbone concentrations were studied. The percent grafting was found to increase initially and then decrease in all the cases except with variation of monomer concentration. The rate of grafting, grafting efficiency, and percent of grafting were calculated. The grafting results have been discussed in the light of the rate of grafting. Mechanical properties, FT IR spectra, percent swelling, and percent dye uptake were carried out on the graft copolymerization and the results discussed.     

Grafting of acryloyl cyanoacetohydrazide onto chitosan

Chitosan was grafted with a novel monomer namely Acryloyl cyanoacetohydrazide (ACAH) which contains carbonyl and cyano groups. The graft copolymerization was conducted in heterogeneous phase using potassium persulfate (K₂S₂O₈) and sodium bisulfite (NaHSO₃) as redox initiators. The effect of monomer concentration, initiator concentration and ratio, time and temperature on the extent of grafting (G%) and the efficiency of grafting were studied. Homopolymer formation has not been observed under all the investigated conditions. The grafted samples were characterized by FTIR spectroscopy, X-ray diffraction and thermogravimetric analysis. The crystallinity of the used chitosan was reduced by grafting. Dye uptake of the grafted samples towards the different types of dyes (acidic, and basic) was investigated and was found to improve profoundly over the native chitosan with a higher uptake for the acidic dye. The grafted samples showed an increased swelling in water, which increased further upon quaternization of the graft copolymers. The extent of swelling is higher in acidic and basic media more than in neutral pH. The quaternized graft copolymer was found to be soluble in water. The fungicidal activity of the quaternized graft copolymers towards three soil-borne sugar beets pathogens was investigated in vitro. The effect on the micro organisms is proportional to the amount of ACAH in the graft copolymer.     

Grafting of acrylate monomers onto chlorinated rubber

Grafting of chlorinated rubber with ethylacrylate and butyl methacrylate in xylene solution has been studied using benzoyl peroxide as the initiator. It is observed that the grafting reaction follows conventional kinetic behavior under the present experimental conditions. The energies of activation obtained for both monomers were 10.8 and 10.95 K.cals, respectively. The grafting efficiency and percent grafting were calculated. Additional proof for grafting onto chlorinated rubber was also obtained by characterization of the graft copolymer by gel permeation chromatography.     

亚甲基丁二酸接枝LDPE

利用反应挤出技术制备了低密度聚乙烯(LDPE)/亚甲基丁二酸接枝物。研究了引发剂种类及用量对接枝率和接枝物熔体流动速率(MFR)的影响。结果表明：采用引发剂L-101的接枝率最高,添加ω(L-101)为0．2％时．接枝率即可接近90％,接枝的同时伴有交联,接枝物的MFR从LDPE的16g／10min下降到2g／10min左右。     

聚烯烃弹性体与马来酸酐的熔融接枝

以双螺杆挤出机作为反应器，比较了聚烯烃弹性体（POE），线性低密度聚乙烯（LLDPE）与马来酸酐（MAH）的熔融接枝反应。尽这两种树脂具有相近的支化度，但由于POE树脂的大支链对大分子自由基之间的偶合反应具有抑制作用，所以，POE/MAH接枝体系的接枝率明显高于LLDPE／MAH接枝体系，而且接枝产物保持了较好的流动性；酸酐在POE树脂上的接枝率随过氧化物和接枝单体用量的增加而增大。接枝树脂可以明显提高PE与铝之间的粘接强度。     

Grafting of polyesters onto carbon whisker surface

Summary Polymerization of N-(p-aminobenzoyl)-caprolactam (PAC) in melts of polyols such as dihydroxy-terminated oligo(oxytetramethylene) with M_n=2000 g/mol at 200°C afforded stable dispersions of poly(p-phenylenebenzamide) whiskers in polyol. In spite of the low molecular weight of the polyaramide, which was isolated by solvent extraction, the microparticles are efficient reinforcing agents of polyurethanes because of the excellent interfacial adhesion resulting from covalent attachment of the polyols onto the microparticle surfaces. The role of the competing formation of p-aminobenzoate-terminated polyols via esterification of PAC was investigated. Morphological and mechanical properties of polyurethane microcomposites, prepared from poly(p-phenylenebenzamide)/poly(oxytetramethylene)diol dispersions and 4,4-diisocyanatodiphenylmethane, were determined as a function of the microparticle content. When compared to conventional polyurethanes, containing equivalent amounts of spherical organic and inorganic fillers, the microcomposites give higher Young's modulus, tensile strength without sacrificing high elongation at break.     

Grafting of 2-butenyl acrylate onto starch

The monomer 2-butenyl acrylate was reacted with starch by exposure to either ⁶⁰Co irradiation or ceric ion initiation. Monomer conversion in the presence of starch is greater than in the absence of starch, indicating that a starch initiating mechanism takes place for ⁶⁰Co irradiated samples. Acetone extraction indicates little or no soluble homopolymer in the grafts. Portions of the samples soluble in dimethyl sulfoxide (DMSO) appear to be low-level 2-butenyl acrylate-grafted starch by infrared analysis. DMSO-insoluble portions (usually more than 50% of each sample) are somewhat more soluble in 1N NaOH at room temperature. This indicates that the 2-butenyl acrylate acts as an easily hydrolyzed crosslink for starch in samples containing as low as 5 wt % grafted poly(2-butenyl acrylate).     

Grafting of styrene onto polyethylene in near critical media

In this work, near critical n‐heptane is used as reaction medium for the copolymerization of polyethylene with styrene monomer, using alkylation reaction with different amounts of aluminum chloride (AlCl₃) as catalyst. In this way, polyethylene chains will be more available to react with the catalyst. The reaction effect on pure reactants, as well as, the catalyst activity was previously investigated. The reaction occurrence was corroborated by analyzing the reaction products before and after careful polystyrene extraction with tetrahydrofuran. The reaction products were characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, scanning electron microscopy, transmission electron microscopy, differential scanning calorimetry, and size exclusion chromatography. The possible architecture for the copolymer molecule was proposed from the molecular characterization results. On the other hand, the polystyrene grafting modifies final properties of polyethylene, increasing the oxygen barrier properties without deteriorating significantly the mechanical properties of the films. In this sense this reaction seems to be a promising route to modify PE films to increase the barrier properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

纤维素接枝共聚改性的若干途径

纤维素接枝共聚是对纤维素进行改性的重要方法之一。本文综述了迄今用于纤维素接枝共聚改性的若干主要途径，其中包括自由基型接枝共聚，离子型接枝共聚以及缩聚型接枝共聚三大类。     

1,6己二醇二丙烯酸酯熔融接枝粉末聚丙烯的研究

通过PP熔融接枝HDDA,研究了各种因素对于接枝率以及熔体流动速率的影响;同时,重点考查了添加苯乙烯作为共单体的影响情况.结果表明190℃、100r/min是反应的最佳条件;增加单体浓度有利于接枝反应;同时,引发剂浓度在0.04%时改性效果明显;添加苯乙烯能有效抑制PP的降解、大幅提高接枝率,改善它的熔体行为;红外和拉伸粘度谱图分别表明了接枝反应的发生以及长链支化结构的存在.