Graft copolymerization of methyl methacrylate on silk fiber using mohr's salt—potassium persulfate as redox initiator under visible light in a limited aqueous medium

Graft copolymerization of methylmethacrylate onto mulberry silk fibers was studied under photoactive conditions with visible light using the Mohr's salt-potassium persulfate as the redox initiator in a limited aqueous medium. Polymerization in the presence of light at 40±1°C was found to be more pronounced than that in the dark at 40±1°C. Percent grafting, percent total conversion, and grafting efficiency under different sets of conditions were studied, and the mechanisms of polymerization and graft copolymer formation were discussed. Characterization of the grafted fibers was done by Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, and thermogravimetry. © 1996 John Wiley & Sons, Inc.     

Study of methyl‐methacrylate‐viscose fiber graft copolymerization and the effect of grafting on thermal properties

The graft copolymerization of methyl‐methacrylate onto viscose fibers was studied under photoactive conditions with visible light using Ce⁴⁺/Ti³⁺ combination as redox initiator in a limited aqueous medium. Polymerization conducted in the presence of light at 30 ± 1°C produced significant grafting, compared with that conducted in the dark under the same conditions. The % grafting, % total conversion, and % grafting efficiency were studied by varying time, monomer concentration, initiator concentration, and pH of the medium. The mechanism of polymerization and graft copolymer formation have been discussed. Characterization of the grafted fibers was done by Fourier transform infrared spectroscopy and scanning electron microscopy. The effect of % grafting on thermal properties was studied by thermogravimetric analysis. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 135–140, 1999     

Photograft copolymerization of methyl methacrylate on silk fiber using titanium(III) chloride–potassium persulphate redox initiator in a limited aqueous system. I

Graft copolymerization of methyl methacrylate (MMA) onto mulberry silk fibers has been investigated in a limited aqueous system employing titanium(III) chloride–K₂S₂O₈ as the redox initiator under a photoactive condition with visible light. Polymerization in the presence of light at 32 ± 1°C has been found to be more pronounced than in the dark under identical conditions. The percentage of grafting, the percentage of total conversion, and the percentage of grafting efficiency have been studied by varying the reaction time, concentration of monomer, initiator concentration, solvent composition, and pH of the medium. A high percentage of grafting (∼ 93%), high grafting efficiency (∼ 97%), and the percentage of total conversion (∼ 25%) have been obtained with little homopolymer formation. Characterization of the grafted fibers has been investigated by Fourier transform infrared spectroscopy and scanning electron microscopy. Finally, the reaction mechanism has been discussed by considering hydrogen bonding. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2187–2193, 1999     

Hydrogen peroxide initiated grafting of acrylamide onto poly(ethylene terephthalate) fibers in benzyl alcohol

The grafting of acrylamide onto poly(ethylene terephthalate) fibers using hydrogen peroxide as the redox initiator was investigated. Benzyl alcohol was found to be the favorite medium for this grafting. Maximum graft yield (7.6%) was reached at 95°C; the graft yield decreased at higher temperatures, and finally grafting was inhibited at 120°C. The effect of monomer and initiator concentration on grafting was also studied. © 1996 John Wiley & Sons, Inc.     

Graft copolymerization with a new class of acidic peroxo salts as initiator. V. Grafting of methyl methacrylate onto jute fiber using potassium monopersulfate catalyzed by Fe(II)

Graft copolymerization of methyl methacrylate (MMA) onto jute fibers was studied in an aqueous solution using a new class of acidic peroxo salt, potassium monopersulfate, as initiator, under the catalytic influence of Fe(II) under nitrogen atmosphere. The grafting reaction was influenced by the reaction time, temperature, and concentrations of monomer, initiator, and jute fibers. The grafting reactions have also been studied in the presence of various salts and solvents. The maximum grafting percent (385.4%) has been observed at 35°C for the concentration of monomer (1.4082M), initiator (12.9 × 10^?3M), catalyst (2.5 × 10^?4M), and solvent (acetic acid) composition of (40:60) for a reaction time of 6 h. From the experimental results a suitable mechanism for the graft initiation and termination has been put forth. The graft copolymers have been characterized, and their improved properties such as tensil strength tested.     

Pentavalent vanadium ion-induced grafting of methyl methacrylate onto cotton cellulose

Graft polymerization of methyl methacrylate (MMA) onto cotton cellulose using vanadium pentanitrate as initiator was studied under a variety of conditions. The graft yield increased with increasing initiator concentration up to 8 mmole/l. and then decreased upon further increase in initiator concentration. Increasing MMA concentration from 1 to 5% was accompanied by a significant increase in the degree of grafting. The latter was also affected by the kind and concentration of the acid incorporated in the polymerization medium. Based on graft yields, the efficiency of the acids follows the order H₂SO₄ > HNO₃ > HClO₄. Replacement of the acid with isopropyl alcohol was also examined. An isopropyl alcohol concentration of 10% constitutes the optimal concentration for grafting. Maximum graft yield depends upon the polymerization temperature; it follows the order 50°C ≥ 60°C > 40°C > 30°C > 70°C. Reaction mechanisms for grafting in the presence of acid as well as in the presence of isopropyl alcohol are proposed.     

Factors affecting polymerization of 2-methyl-5-vinylpyridine in poly(ethylene terephthalate) fibers using benzoyl peroxide as initiator

Polymerization of 2-methyl-5-vinylpyridine (MVP) in the presence of poly(ethylene terephthalate) fibers (PET) using benzoyl peroxide (BP) as initiator caused a substantial increase in the weight of fibers. The mechanism of this polymerization is believed to be grafting by vinyl addition to PET radical formed under the influence of BP. Increasing the BP concentration up to 4.26 × 10^?3 mole/l. causes a significant enhancement in grafting, while further increase brings about a marked fall in the graft yield. Increasing the MVP concentration up to 10% also improves significantly the graft yield, but the latter, particularly in the later stages of the reaction, shows lower values at higher MVP concentrations. Raising the reaction temperature from 65° to 95°C causes a significant enhancement in the rate of grafting, though the maximum graft yield obtained at 95°C is much lower than at 85°C. Incorporation of Cu²⁺ ion in the polymerization system enhances the graft yield outstandingly. The same holds true for Fe³⁺ and Li ions, but the enhancement is much less than for Cu²⁺ ion. Addition of acetic or oxalic acid to the reaction decreases the magnitude of grafting. The same situation is encountered when a water/solvent mixture is used as reaction medium. Solvents employed were methanol, ethanol, propanol, and butanol. Also studied was the polymerization reaction with respect to homopolymer, total conversion, and graft efficiency.     

Grafting onto wool. XIV. Graft copolymerization of vinyl monomers by use of Mn(AcAc)3 as an initiator

Ethyl acrylate (EA), butyl acrylate (BA), and vinyl acetate (VAc) have been graft copolymerized onto Himachali wool fiber in an aqueous medium by using Mn(AcAc)₃ as an initiator. Graft copolymerization was studied at 45°, 55°, 65° and 75°C for various reaction periods. Percentage of grafting and percent efficiency were determined as functions of concentration of monomer, concentation of initiator, concentration of nitric acid, time, and temperature. Several grafting experiments were carried out in the presence of various additives which included: (i) pyridine and (ii) Et₃ N. EA, BA, and VAc were found to differ in reactivity towards grafting and followed the order: EA > BA > VAc.     

Graft copolymerization of an itaconic acid/acrylamide monomer mixture onto poly(ethylene terephthalate) fibers with benzoyl peroxide

A mixture of acrylamide (AAm) and itaconic acid (IA) was grafted onto poly(ethylene terephthalate) (PET) fibers with benzoyl peroxide in aqueous media. The effects of polymerization conditions such as the temperature, polymerization time, initiator concentration, and monomer mixture ratio on grafting were investigated. The maximum graft yield was 76.1% with an AAm/IA mixture ratio of 90/10 (mol/mol). The graft yield was as low as 3% in the single grafting of IA, whereas the use of AAm as a comonomer increased the amount of IA that entered the fiber structure to 33.5%. An increase in the temperature from 65 to 85°C increased the grafting rate and saturation graft yield. However, an increase in the temperature above 85°C decreased the saturation graft yield. The graft yield increased up to an initiator concentration of 1.0 × 10^?2 M and decreased afterwards. The grafting rate was 0.65th‐ and 0.74th‐order with respect to the initiator and AAm concentrations, respectively. The densities, diameters, and moisture‐regain values of the AAm/IA‐grafted PET fibers increased with the graft yield. Similarly, there was an increase in the dyeability of the AAm/IA‐grafted fibers with acidic and basic dyes. The grafted fibers were characterized with Fourier transform infrared and thermogravimetric analysis, and their morphologies were examined with scanning electron microscopy. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1795–1803, 2005     

以Fe2+-H2O2氧化还原体系引发木薯淀粉与醋酸乙烯酯接枝共聚反应研究

研究了以Fe2+-H2O2为引发剂的木薯淀粉与醋酸乙烯酯的接枝共聚反应,并对重要的反应条件进行了讨论。结果表明:当单体与淀粉的质量配比为1.0~2.0,引发剂浓度为1.0 mmol/L,H2O2与Fe2+的摩尔比为2,反应温度为40°C,反应时间为3 h,采用Fe2+→单体→H2O2的加料顺序时,可以得到较高的转化率、接枝率、接枝效率,分别为86.47%、55.30%及31.98%,并探讨Fe2+-H2O2的引发机理。通过Srectrum One红外光谱及电镜对接枝物的结构进行了分析。     

Synthesis and properties of chitosan-modified poly(vinyl butyrate)

Modification of chitosan by grafting of vinyl butyrate was carried out in homogeneous phase using potassium persulfate as redox initator and 1.5% acetic acid as solvent. The percent grafting and grafting efficiency were analysed and the high grafting efficiency up to 94% was observed. The effects of reaction variables such as monomer concentration, initiator concentration, temperature and reaction time were investigated. It was observed that the solubility of chitosan was markedly reduced after grafting with vinyl butyrate. The grafted product is insoluble in common organic solvents as well in dilute organic and inorganic acids. Characterization of the graft copolymers were carried out by using Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC) and Scanning Electron Microscopy (SEM) technics. Characteristic signal of carbonyl group was observed at 1,731 cm⁻¹ which belongs to the poly vinyl butyrate segments in the graft copolymer. The melting transition of the chitosan main chain in the copolymer shifted to 124°C from its original value 101°C. In addition to these, we have also studied topology of the graft copolymer and the SEM micrograph showed continuous homogenous matrix which means there is no phase separation.     

Modification of carbohydrate polymers via grafting of methacrylonitrile onto pregelled starch using potassium monopersulfate/Fe2+ redox pair

The graft copolymerization of reactive pregelled starch (PGS) with methacrylonitrile (MAN) was performed and the reaction conditions were optimized using potassium monopersulfate (PMPS) in the presence of ferrous ion redox pair as initiator. Emphasis was directed towards increasing the graft formation and decreasing homopolymerization. The grafting parameters were studied with respect to graft yield and graft reaction efficiency percent. In addition, the newly prepared polymethacrylonitrile (polyMAN)‐pregelled starch graft copolymers were applied to cotton textiles to see their suitability as a new sizing agent. Based on the results obtained, appropriate conditions for grafting MAN onto pregelled starch was established and the graft yield was higher under the following conditions: using 0.004 mol l^?1 potassium monopersulfate as initiator, 0.005 mol l^?1 ferrous ion concentration, 0.003 mol l^?1, sulfuric acid, 50 % MAN concentration (based on weight of substrate), material to liquor ratio 1:2.5, reaction time 60 min, and polymerization temperature 40 °C. Finally, fabric samples sized with polyMAN‐pregelled starch graft copolymers acquired higher tensile strength and abrasion resistance than that sized with original pregelled starch, while elongation at break was unaltered. Copyright © 2004 Society of Chemical Industry     

Synthesis and characterization of graft copolymers of ethyl acrylate/acrylamide mixtures onto starch

Graft copolymerization of ethyl acrylate/acrylamide onto corn starch using potassium permanganate–citric acid initiation system was investigated. Major factors affecting the polymerization reaction were thoroughly investigated in terms of initiator concentration, monomer concentration, polymerization time, polymerization temperature, and starch/liquor, and the obtained results implied that the polymer yield which were expressed by total monomer conversion, grafting ratio, and grafting efficiency were determined by these factors. The optimum reaction conditions were as follows: starch, 30 g; potassium permanganate (based on weight of starch), 0.1%; citric acid (based on weight of starch), 0.5%; ethyl acrylate, 20%; acrylamide, 0.4 g; time, 3 h; temperature, 40°C; starch/liquor, 1:3. We concluded that the initiator of potassium permanganate–citric acid system could be used as a cheap initiator in manufacturing the starch graft copolymer. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

淀粉-MMA接枝共聚物的半干法合成新工艺

以硝酸铈铵(CAN)为引发剂,采用固相半干法合成了玉米淀粉(CS)接枝甲基丙烯酸甲酯(MMA)共聚物。考察了含水量、反应体系的酸性、反应时间与温度、MMA单体和引发剂CAN用量等因素对接枝共聚反应的影响。结果表明,体系含水质量分数为35%左右,CAN用量为CS质量的1.5%～3%,反应温度在40～50℃,反应时间为0.5h左右,可得到接枝率、接枝效率和单体转化率均较高的接枝共聚物。     

Ni(Ⅳ)引发丙烯酸甲酯与三元尼龙接枝共聚反应的研究

以二过碘酸合镍(Ⅳ)钾〔Ni(Ⅳ)〕为氧化剂,共聚尼龙上的弱的还原基团(酰胺基)为还原剂,组成氧化还原引发体系,于碱性介质中直接在共聚尼龙分子骨架上产生接枝点,引发丙烯酸甲酯(MA)的接枝共聚合反应,获得了较高的接枝效率(可达90%以上)。探讨了引发剂浓度、单体浓度、反应温度对接枝参数的影响,结果表明:当c〔Ni(Ⅳ)〕=8×10-4mol/L,c(MA)=1 5mol/L,θ=35℃时,接枝效率和接枝百分比可达到最高值。用红外光谱、X射线衍射、扫描电镜对接枝共聚物进行了表征,提出了建立在镍(Ⅳ)还原为镍(Ⅱ)的过程为两步单电子转移的基础之上的引发机理。将所得接枝共聚物用作尼龙/聚甲基丙烯酸甲酯体系的增容剂,通过扫描电镜分析表明:该共混体系的相容性得到一定程度的改善。     

Synthesis and characterization of butyl acrylate graft sodium salt of partially carboxymethylated starch

Graft copolymers were synthesized by graft copolymerization of butyl acrylate (BA) onto sodium salt of partially carboxymethylated starch (Na‐PCMS). Ceric ammonium nitrate (CAN), a redox initiator, was used for initiation of graft copolymerization reaction. All the experiments were run with Na‐PCMS having degree of substitution, DS = 0.35. The grafting reaction was characterized by parameters such as % total conversion (%Ct), % grafting (%G), % grafting efficiency (%GE), and % add‐on. Graft copolymers were characterized by infrared spectral analysis and scanning electron microscopy. Variables affecting graft copolymerization reaction such as nitric acid concentration, reaction time, reaction temperature, and ceric ion concentration were investigated. The results revealed that 0.3M CAN as initiator, 0.3M HNO₃, with reaction time 4–4.5 h at 25–30°C were found as suitable parameters for maximum yield of graft copolymerization reaction. © 2006 Wiley Periodicals, Inc. JAppl Polym Sci 102: 3334–3340, 2006     

H2O2-induced graft polymerization of acrylic acid/styrene mixtures on poly(ethylene terephthalate) fibers

Graft polymerization of acrylic acid/styrene mixtures on poly(ethylene terephthalate) fibers using H₂O₂ as initiator was investigated under different conditions including acrylic acid/styrene ratio, monomer mixtures concentration, initiator concentration, polymerization temperature, pH of polymerization medium, addition of metallic salts, and use of solvent/water mixture instead of aqueous medium. It was found that the rate and extent of grafting for acrylic acid/styrene mixtures were much higher than those of single monomers, indicating a synergestic effect. Maximum percent grafting occurred when acrylic acid/styrene mixture at a ratio of 30:70 was used. Increasing the monomer mixture concentration from 2% to 40% was accompanied by a significant enhancement in percent grafting. The latter increased also significantly as the H₂O₂ concentration increased from 10 to 150 meq/L; a further increase in H₂O₂ concentration decreased grafting. No grafting took place at 65°C even after 4 h. Raising the polymerization temperature to 75°C expedited grafting; the magnitude of the latter increased by increasing the temperature up to 95°C. Addition of copper sulphate and ferrous ammonium sulphate to the polymerization system offset grafting, the opposite holds true for lithium chloride provided that its concentration does not exceed 15 mmole/L. Methyl alchol/water mixture (20:80) constituted the optimal medium for polymerization. Grafting of acrylic acid/styrene mixtures to poly(ethylene terephtalate) fibers resulted in considerable improvement in moisture regain of the latter.     

Synthesis,characterization, and biodegradation of carboxymethylchitosan‐g‐medium chain length polyhydroxyalkanoates

Grafting of medium chain length polyhydroxyalkanoates (mcl‐PHA) produced by Comamonas testosteroni onto carboxymethylchitosan (CMCH) using ceric ammonium nitrate (CAN) as an initiator was carried out under nitrogen atmosphere in aqueous medium. The grafting composition was 2 g CMCH, 0.2M CAN, and 0.5 g mcl‐PHA. The reaction was carried out at 40°C ± 1°C for 4.5 h, and reaction product was extracted by acetone precipitation. The CMCH‐g‐mcl‐PHA copolymers were characterized by Fourier transform infrared spectroscopy, Thermogravimetric analysis, differential scanning calorimetry, and scanning electron microscopy. The data obtained showed successful grafting of mcl‐PHA onto CMCH polymer. TGA results indicated that the graft was stable up to 380°C, and the solubility studies revealed a high % grafting efficiency. Biodegradation studies of the graft in terms of microbial growth, extracellular protein concentration, and % weight loss in the graft were carried out for 30 days using a bacterial isolate Burkholderia cepacia 202 and a fungal isolate Aspergillus fumigatus 202. 93% weight loss of the graft was obtained in case of A. fumigatus 202, whereas B. cepacia 202 showed 76% loss in weight of the graft. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of graft copolymerization of 2-hydroxyethyl methacrylate on the properties of polyester fibers and fabric

Graft copolymerization of hydroxyethyl methacrylate (HEMA) onto poly(ethylene terephthalate) (PET) fibers using benzoyl peroxide (BP) as initiator was carried out in water and in water/organic solvent as a reaction medium. The effect of initiator concentration, reaction time, temperature, and reaction medium as well as addition of FeSO₄ to the polymerization medium was studied. Percent grafting was enhanced significantly by increasing BP concentration up to 0.016 mol/L and then decreased upon further increase in initiator concentration. Increasing the monomer (HEMA) concentration up to 0.48 mol/L improves significantly the graft yield. Raising the polymerization temperature up to 85°C causes a significant increase in grafting yield; further increase in temperature leads to decrease in graft yield. Incorporation of Fe⁺² ions in the polymerization system decrease the graft yield. The same situation is encountered when water/solvent mixture is used as reaction medium. Solvent employed were methanol, toluene, and benzene.     

Preparation of high PMMA grafted particle SiO2 using surface initiated free radical polymerization

In this work, a convenient surface-initiated free radical graft-polymerization method, by which polymethacrylic acid (PMAA) with a high grafting density was grafted on silica gel particles, was put forward, and it was feasible and effective. The coupling agent γ-aminopropyltrimethoxysilane (AMPS) was first bound onto the surfaces of silica gel particles, obtaining the modified particles AMPS-SiO₂. So a redox initiation system was constituted with the amino groups on the surfaces of AMPS-SiO₂ particles and ammonium persulphate in the solution. A great deal of primary free radicals on the surfaces of AMPS-SiO₂ particles is produced via the redox initiating reaction, so that the surface-initiated free radical graft- polymerization of methacrylic acid (MAA) on the silica gel particles was realized, giving the grafted particles PMAA/SiO₂ with a high grafting degree (about 30 g/100 g) of PMAA. The effects of the main factors on the surface initiated graft polymerization were examined and the corresponding mechanism was investigated in depth. The experimental results show that for this surface-initiated free radical graft-polymerization of MAA, the suitable temperature is 40 °C. If the temperature is over 40 °C, the graft polymerization will be affected negatively, and the grafting degree of PMAA will decline because of the intense heat decomposition of ammonium persulphate. During the graft polymerization, the grafted polymer layer that has formed is a hindrance to the subsequent graft polymerization. The used amount of initiator and the monomer concentration affect the graft polymerization greatly. The appropriate reaction conditions are as follows: reaction time of 10 h, initiator persulphate amount of 1.1% (it implies the mass percent of the monomer), and monomer MAA concentration of about 5% (it drives at the mass percent of the solution).