Effect of grafting methacrylate monomers onto jute constituents with a potassium persulfate initiator catalyzed by Fe(II)

The graft copolymerization of methyl methacrylate and ethyl methacrylate monomers onto jute fiber was carried out in an aqueous medium with potassium persulfate as an initiator under the catalytic influence of ferrous sulfate in the presence of air. The effects of parameter variables, such as the monomer, initiator, and catalyst concentrations, the reaction time, and the temperature, on grafting and the effect of grafting the monomers onto jute constituents were studied. The degree of grafting depended on the kinds of monomers and the parameter variables. The maximum graft yield percentages with methyl methacrylate and ethyl methacrylate under optimized conditions were 18.9 and 38.8%, respectively, and the grafting onto jute fiber was largely affected by one of its main constituents, such as hemicellulose. The graft copolymers were characterized, and their improved properties were also examined. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2369–2375, 2007     

Graft copolymerization of methyl acrylate onto poly(vinyl alcohol) initiated by potassium diperiodatoargentate(III)

The graft copolymerization of methyl acrylate onto poly(vinyl alcohol) (PVA) using potassium diperiodatoargentate(III) [Ag(III)]–PVA redox system as initiator was studied in an alkaline medium. Some structural features and properties of the graft copolymer were confirmed by Fourier‐transfer infrared spectroscopy, scanning electron microscope, X‐ray diffraction and thermogravimetric analysis. The grafting parameters were determined as a function of concentrations of monomer, initiator, macromolecular backbone (X?_n = 1750, M? = 80 000 g mol^?1), reaction temperature and reaction time. A mechanism based on two single‐electron transfer steps is proposed to explain the formation of radicals and the initiation profile. Other acrylate monomers, such as methyl methacrylate, ethyl acrylate and n‐butyl acrylate, were also used to produce graft copolymerizations. It has been confirmed that grafting occurred to some degree. Thermogravimetric analysis was performed in a study of the moisture resistance of the graft copolymer. Copyright © 2004 Society of Chemical Industry     

Synthesis of cassava starch‐g‐poly(methyl methacrylate) copolymers with benzoyl peroxide as an initiator

Graft copolymers of cassava starch and methyl methacrylate (MMA) were synthesized by free‐radical polymerization with benzoyl peroxide (BPO) as an initiator in an aqueous medium at 80°C. The formation of graft copolymers was confirmed by analysis of the obtained products with Fourier transform infrared spectroscopy and scanning electron microscopy. The effects of the amount of cassava starch, the amount of MMA monomer, the amount of BPO, and the reaction time on the grafting characteristics were studied. The optimum condition for grafting were obtained when 5 g of cassava starch, 5 g of MMA, 0.1 g of BPO, and a reaction time of 3 h were used. These condition provided a graft copolymer with 25.00% add‐on, 81.40% monomer conversion, 54.30% homopoly(methyl methacrylate) formed, 45.70% grafting efficiency, 37.20% grafting ratio, and 95.54% yield. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4083–4089, 2006     

Grafting onto wool. XI. Graft copolymerization of poly(vinyl acetate) and poly(methyl acrylate) onto reduced wool in presence of potassium persulfate–ferrous ammonium sulfate (KPS—FAS) system as redox initiator

In an attempt to ascertain the role of—SH groups of Himachali wool during graft copolymerization, poly(viny acetate) (PVAc) and poly(methyl acrylate) (PMA) were graft copolymerized onto reduced wool by using potassium persulfate—ferrous ammonium sulfate (KPS—FAS) redox pair in aqueous medium. Reduction of wool was carried out by sodium bisulfite solution of varying concentrations for different reaction periods. Concentration of reducing agent and the extent of reduction were found to influence grafting of vinyl monomers. Maximum grafting of methyl acrylate (MA) and vinyl acetate (VAc) occurred when wool was reduced by 1% and 0.5% NaHSO₃ solution, respectively, for 24 h. Increase in percent grafting of MA onto reduced wool compared to that of unreduced wool has been ascribed to the production of more—SH groups by reduction of—SS—groups of wool fiber.     

Natural rubber‐g‐methyl methacrylate/poly(methyl methacrylate) blends

The grafting of the methyl methacrylate (MMA) monomer onto natural rubber using potassium persulfate as an initiator was carried out by emulsion polymerization. The rubber macroradicals reacted with MMA to form graft copolymers. The morphology of grafted natural rubber (GNR) was determined by transmission electron microscopy and it was confirmed that the graft copolymerization was a surface‐controlled process. The effects of the initiator concentration, reaction temperature, monomer concentration, and reaction time on the monomer conversion and grafting efficiency were investigated. The grafting efficiency of the GNR was determined by a solvent‐extraction technique. The natural rubber‐g‐methyl methacrylate/poly(methyl methacrylate) (NR‐g‐MMA/PMMA) blends were prepared by a melt‐mixing system. The mechanical properties and the fracture behavior of GNR/PMMA blends were evaluated as a function of the graft copolymer composition and the blend ratio. The tensile strength, tear strength, and hardness increased with an increase in PMMA content. The tensile fracture surface examined by scanning electron microscopy disclosed that the graft copolymer acted as an interfacial agent and gave a good adhesion between the two phases of the compatibilized blend. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 428–439, 2001     

Synthesis of nanosized poly(ethyl acrylate) particles via differential emulsion polymerization

Nanoparticles of poly(ethyl acrylate) were synthesized via a semibatch differential emulsion polymerization method with potassium persulfate as the initiator and sodium dodecyl sulfate as the surfactant. The effects of the reaction temperature, aging time, and surfactant/initiator/monomer ratios on the polymer particle sizes were investigated. Poly(ethyl acrylate) with particle sizes of less than 20 nm was synthesized under mild conditions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1609–1614, 2006     

Graft copolymerization of methyl acrylate onto poly(vinyl alcohol) initiated by potassium diperiodatonickelate(IV)

The graft copolymerization of methyl acrylate onto poly(vinyl alcohol) (PVA) with a potassium diperiodatonickelate(IV) [Ni(IV)]–PVA redox system as an initiator was investigated in an alkaline medium. The grafting parameters were determined as functions of the temperature and the concentrations of the monomer and initiator. The structures of the graft copolymers were confirmed by Fourier transform infrared spectroscopy, scanning electron microscopy, X‐ray diffraction, differential scanning calorimetry, and thermogravimetric analysis. The Ni(IV)–PVA system was found to be an efficient redox initiator for this graft copolymerization. A single‐electron‐transfer mechanism was proposed for the formation of radicals and the initiation. Other acrylate monomers, such as methyl methacrylate, ethyl acrylate, n‐butyl acrylate, and n‐butyl methacrylate, were used as reductants for graft copolymerization. These reactions definitely occurred to some degree. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 529–534, 2003     

引发剂对纤维素接枝丙烯酰胺反应的影响

分别以硝酸铈铵、过硫酸钾和过硫酸钾/亚硫酸钠为引发剂,以马尾松漂白硫酸盐浆纸浆纤维素为骨架接枝丙烯酰胺,在单体浓度为0.75 mol/L、温度为45℃、反应时间为3 h时,得到硝酸铈铵和过硫酸钾的最佳浓度为3.0 mmol/L和5.0 mmol/L,过硫酸钾/亚硫酸钠在用量为6%时的最佳质量比为1.5,三者相应的接枝率分别为40%、48%和60%。同时比较了不同条件下三种引发剂的接枝效果,结果表明,过硫酸钾/亚硫酸钠的接枝效果最好,但均聚物含量高;硝酸铈铵作为引发剂虽然接枝效果不及前两者,但均聚物含量很低。     

Synthesis,characterization, and thermal behavior study of methyl methacrylate polymers containing 4‐carbazole substitutes

A new polymerizable monomer, [4‐(9‐ethyl)carbazolyl]methyl methacrylate ( 2 ), was synthesized by reacting of methacrylic acid and 4‐hydroxymethyl‐9‐ethyl carbazole ( 1 ) by esterification procedure in the presence of N,N′‐dicyclohexylcarbodiimide. The resulting monomer was then polymerized free‐radically to form the poly(methyl methacrylate) containing 4‐(9‐ethyl)carbazolyl pend ent groups. Also, copolymerization of monomer 2 with various acrylic monomers such as methyl methacrylate, ethyl methacrylate, methyl acrylate, ethyl acrylate, and n‐butyl acrylate by azobisisobutyronitrile as a free radical polymerization initiator gave the related copolymers in high yields. The structure of all the resulted compounds was characterized and confirmed by FTIR and ¹H NMR spectroscopic techniques. The average molecular weight of the obtained polymers was determined by gel permeation chromatography using tetrahydrofurane as the solvent. The thermal gravimetric analysis and differential scanning calorimeter instruments were used for studying of thermal properties of polymers. It was found that, with the incorporation of bulky 4‐(9‐ethyl)carbazolyl substitutes in side chains of methyl methacrylate polymers, thermal stability and glass transition temperature of polymers are increased. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4989–4995, 2006     

聚甲基丙烯酸甲酯预聚物作为助稳定剂的细乳液聚合速率研究

以聚甲基丙烯酸甲酯(PMMA)预聚物为助稳定剂、十二烷基硫酸钠为乳化剂、十六醇为助乳化剂和过硫酸钾为引发剂,研究甲基丙烯酸甲酯(MMA)的细乳液聚合反应速率.考察乳化剂浓度、助乳化剂浓度、引发剂浓度、预聚物浓度、预聚物分子量以及反应温度对聚合速率的影响.结果表明:聚合速率RP随着乳化剂浓度或反应温度的提高而增加,随着助乳化剂浓度的提高而减小,引发剂浓度对RP影响不明显.在相同条件下,加入预聚物的细乳液体系聚合速率RP在聚合反应前期比常规细乳液有明显提高:PMMA(MH=520000)浓度为2×10-3mmol·L-1时,RP的最大峰值为1.84×10-2mol·L-1·min-1.预聚物PMMA在MMA细乳液聚合体系中,可以提高聚合速率和增加体系稳定性.     

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.     

Synthesis of poly(epichlorohydrin‐g‐methyl methacrylate) graft copolymers by the combination of cationic and atom transfer radical polymerization

Poly(epichlorohydrin) possessing chloromethyl side groups in the main chain was used in the atom transfer radical polymerization of methyl methacrylate and styrene to yield poly(epichlorohydrin‐g‐methyl methacrylate) and poly(epichlorohydrin‐g‐styrene graft copolymers. The polymers were characterized by ¹H NMR spectroscopy, gel permeation chromatography, differential scanning calorimetry, and fractional precipitation method. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2725–2729, 2006     

Emulsion polymerization of styrene and DEAEMA with a core–shell structure

Polystyrene–poly(N,N‐diethylamino ethyl methacrylate) (PS–PDEAEMA) particles with a core–shell morphology were prepared by seeded emulsion polymerization. Poly(oxyethylene) (POE) (n = 15 and 30) nonyl phenol and sodium lauryl sulfate (SLS) were used as emulsifiers. These two emulsifiers were selected in order to study the effect of nonionic and ionic emulsifiers on the reaction because of the basic character of DEAEMA. The core–shell morphology was investigated independently in the presence of water‐soluble potassium persulfate (KPS) and of oil‐soluble azobisisobutyronitrile (AIBN). The morphologic structure of the particles was studied using scanning electron microscopy and transmission electron microscopy. The latex particles and the polymers were characterized by differential scanning analysis, thermogravimetric analysis, and gel permeation chromatography. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1977–1985, 2000     

Grafting of a styrene–acrylonitrile binary monomer mixture onto cellulose extracted from pine needles

In an attempt to develop new reactive membrane materials, we graft‐copolymerized styrene (Sty) and acrylonitrile (AN) onto cellulose extracted from pine needles by a chemical initiation method. The optimum grafting reaction conditions for Sty onto cellulose were earlier evaluated as [Sty] = 656.25 mmol/L and [potassium persulfate–ferrous ammonium sulfate] = 146.3:12.75mmol/L in 20 mL of H₂O with a reaction time of 3 h and a reaction temperature of 60°C for 1 g of cellulose. Under these conditions, Sty was graft‐copolymerized with AN at five different concentrations of the latter. Grafting parameters and different rates of concentration were evaluated. The effects of additives such as ZnCl₂, LiNO₃, and Cu(NO)₃ were studied at the best comonomer concentration of Sty–AN. In the presence of ZnCl₂, Sty–AN graft‐copolymerized in an alternate way, thus, making it evident that ZnCl₂ coordinated to form a “complexomer,” or complex of monomers [Sty^?AN⁺…ZnCl₂], of two monomers. Evidence of the structural characteristics of grafted chains were provided by characterization with elemental analysis, thermal analysis, and Fourier transform infrared spectroscopy. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2000–2007, 2002     

Graft copolymerization of methyl methacrylate onto rubber‐wood fiber using H2O2 and Fe2+ as an initiator system

Methyl methacrylate (MMA) was successfully grafted onto rubber‐wood fiber in a free‐radical solution polymerization initiated by ferrous ion and hydrogen peroxide. The effects of the reaction parameters (reaction temperature, reaction period, influence of hydrogen peroxide, ferrous ammonium sulfate, and monomer concentrations) were investigated. The grafting percentage showed dependency on H₂O₂, Fe²⁺, and monomer concentrations, as well as reaction temperature and reaction period. The optimum reaction temperature was determined to be about 60°C and the reaction period was 60 min. The optimum concentration of H₂O₂ was 0.03M and optimum amounts of Fe²⁺ and MMA were 0.26 mmol and 2.36 × 10^?2 mol, respectively. Poly(methyl methacrylate) (PMMA) homopolymer was removed from the graft copolymer by Soxhlet extractor using acetone. The presence of PMMA on the fiber was shown by FT‐IR spectroscopy and gravimetric analysis. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2499–2503, 2003     

Graft copolymerization of vinyl monomers on cellulosic materials

Graft copolymers of acrylonitrile, ethyl acrylate, methyl acrylate, ethyl methacrylate and methyl methacrylate and of acrylonitrile/ethyl methacrylate and acrylonitrile/methyl methacrylate monomer mixtures on carboxymethylcellulose (degree of substitution 0.4–0.5) were prepared by use of ceric ion initiator in aqueous medium. The extent of graft polymer formation was measured in terms of graft level, molecular weight of grafted polymer chains and frequency of grafting as function of ceric ion concentration. It was found that at comparable reaction conditions, the molecular weight and frequency of grafting were not of the same order of magnitude. For the monomer mixtures, the copolymer compositions obtained from the total nitrogen content of the acrylonitrile/alkyl methacrylate copolymer samples showed that a relativity low amount of the acrylonitrile monomeric units were incorporated into the graft copolymer even at high acrylonitrile content of the feed.     

Multifunctional characteristics of new carboxymethylcellulose‐based graft copolymers for oilfield drilling

New carboxymethylcellulose‐based graft copolymers with an amphoteric character were synthesized by grafting 2‐(dimethylamino)ethyl methacrylate onto carboxymethylcellulose using a persulfate‐initiated solution polymerization technique. Their multifunctional characteristics as an oilfield drilling–mud additive were investigated with respect to shale inhibition, viscosity building, and filtration control. It was shown that the graft copolymer with an appropriate grafting extent is characteristic of both good shale inhibition and mud properties and may overcome the limitations inherent in commonly used anionic and cationic polymeric additives. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 195–201, 2000     

EA-MMA共聚乳液合成工艺及优化

以丙烯酸乙酯(EA)和甲基丙烯酸甲酯(MMA)为共聚单体、过硫酸钾(KPS)为引发剂、十二烷基硫酸钠(SDS)和壬基酚聚氧乙烯醚(OP-10)为复合乳化剂,采用乳液聚合法合成出一种稳定的EA-MMA乳液。通过单因素试验法考察了乳化剂浓度、引发剂浓度、反应温度和反应时间等因素对乳液平均粒径和单体转化率的影响,并采用正交试验法进一步优选出制备EA-MMA乳液的最佳工艺条件。结果表明:当w(乳化剂)=2.0%、w(引发剂)=0.60%、反应时间为4 h和反应温度为80℃时,制成的EA-MMA乳液较稳定,并且单体转化率相对最高。     

Strategies for improving graft degree of urethane derivative of 2‐hydroxymethyl methacrylate grafted onto LDPE

A novel monomer, 2‐methyl‐acrylic acid 2‐(3‐isocyanato‐2‐methyl‐phenyl carbamoyloxy)‐ethyl ester (HT), was synthesized by the reaction of 2‐hydroxymethyl methacrylate with toluene diisocyanate. The influences of solvents, temperature and catalyst, dibutyl tin dilaurate on the total yield of HT were investigated and theoptimum synthesis conditions were obtained. The obtained monomer was then used to modify low density polyethylene (LDPE) in the Haake Rheomix 600P via melt grafting copolymerization. The modified LDPE was characterized by Fourier transform infrared. During the grafting process, single‐step and two‐step procedures were compared and the results showed that the two‐step procedure was more favorable. In a two‐step procedure, the influences of melting temperatures, monomer amount, and ethylene vinyl acetate copolymer (EVA, M_n = 800–1200) on the graft degree were also investigated. The investigation confirmed that EVA acting as a dispersant could enhance the dispersion of the monomer and improve graft degree significantly, and net value of increased graft degree was about 1.5%. The better dispersion of HT in the matrix of LDPE was confirmed via scanning electron microscope after adding EVA to the system. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

THERMOPLASTIC POLYMERS AND ELASTOMER-BASED MULTIPHASE SYSTEMS. I. POLYMERIZATION OF METHYL METHACRYLATE IN PRESENCE OF POLYBUTADIENE

The aim of this article is the polymerization of methyl methacrylate, containing dissolved polybutadiene, in the presence of methyl ethyl ketone peroxide–cobalt octoate as the redox initiating system. The influence of several factors, such as the polymerization temperature and the concentration of the elastomer and of the initiating system, on the characteristics of the process (e.g., the highest temperature attained in the reaction system, the time of settling the maximum reaction rate and of the phase inversion) was also studied. At the end of the process, a composite material of high impact strength, based on the poly(methyl methacrylate) matrix incorporating dispersed fine elastomer particles, was obtained.