Photoinitiated graft copolymerization of hydroxyethyl methacrylate onto cotton cellulose

The photoinitiated graft copolymerization of hydroxyethyl methacrylate (HEMA) onto cotton cellulose was studied using uranyl nitrate (UN) and ceric ammonium nitrate (CAN) photoinitiators. Optimization of various parameters of the graft-copolymerization reaction viz., time, temperature, initiator, and monomer concentration, was carried out. The optimized conditions of grafting were employed to cotton samples swollen in zinc chloride as well as sodium hydroxide. Graft add-on was found to be dependent on the nature of substrate and the concentrations of monomer and photoinitiator. UN was found to be the better photoinitiator, giving higher grafting with HEMA. The grafted samples showed initially decrease and then marginal increase in the moisture regain with increase in graft add-on. The dye uptake of both direct and reactive dyes decreased with increase in graft add-on.     

Ultraviolet-radiation-induced graft copolymerization of styrene and acrylonitrile onto cotton cellulose

Photoinitiated graft copolymerization of the vinyl monomers, styrene and acrylonitrile, onto cotton cellulose was studied using uranyl nitrate and ceric ammonium nitrate as photoinitiators. Uranyl nitrate photoinitiation showed a higher level of grafting for styrene, whereas in the case of acrylonitrile ceric ammonium nitrate was found to be the better photoinitiator. Optimized conditions of grafting, when employed to cotton swollen with sodium hydroxide and zinc chloride, enhanced the graft levels for both monomers. Grafted samples were subjected to thermal analysis, as well as estimation of moisture regain and tenacity. Thermal stability increased, whereas, the moisture regain and tenacity decreased, with the increase in graft add-on in the case of both monomers. Acrylonitrile-grafted cotton showed dyeability with cationic dye that improved with the level of graft add-on. Possible explanations have been given.     

Improving graft level during photoinduced graft-copolymerization of styrene onto cotton cellulose

Styrene was graft-copolymerized onto cotton cellulose using photoinitiators uranyl nitrate (UN), ceric ammonium nitrate (CAN), and benzoin ethyl ether (BEE) under ultraviolet radiation. UN gave somewhat higher graft add-on. Preswelling of the substrate or using divinyl benzene in the grafting bath gave an increased level of graft, the later technique being more efficient. The moisture regain and tenacity decreased, whereas thermal stability increased in proportion to the graft add-on. © 1993 John Wiley & Sons, Inc.     

Mechanical and thermal behavior of cotton cellulose graft-copolymerized using hydroxyethyl methacrylate in presence of triethylene glycol dimethacrylate

UV-radiation-induced graft-copolymerization of cotton cellulose was carried out with 2-hydroxyethyl methacrylate (HEMA) in the presence of small amounts of triethylene glycol dimethacrylate (TEGDMA) using benzoin ethyl ether (BEE), uranyl nitrate (UN), and ceric ammonium nitrate (CAN) as photoinitiators. The presence of very small amounts of (TEGDMA) in the HEMA grafting bath led to great enhancement in the graft add-on as compared to that obtained on the sodium hydroxide-preswollen substrate. With increase in the graft add-on, the breaking load of cotton decreased, whereas its thermal stability improved © 1993 John Wiley & Sons, Inc.     

Ultraviolet radiation-induced graft copolymerization of 2-hydroxyethyl methacrylate onto polypropylene

Polypropylene staple fibers were grafted with 2-hydroxyethyl methacrylate (HEMA) using ultraviolet radiation in the presence of three different photoinitiators, uranyl nitrate (UN), ceric ammonium nitrate (CAN), and benzoin ethyl ether (BEE), separately. The parameters of grafting were optimized for obtaining maximum graft add-on. BEE appeared to be a better photoinitiator than the other two, giving maximum possible graft add-on. CAN, as a chemical initiator, did not show significant improvement in grafting. The moisture regain of the grafted polypropylene increased in proportion with the graft add-on. Dyeing with reactive dye could give only light color to the grafted fiber. Possible explanations have been given. © 1994 John Wiley & Sons, Inc.     

Ultraviolet-radiation induced graft-copolymerization of hydroxyethyl methacrylate onto cotton cellulose

Two-hydroxyethyl methacrylate was grafted onto cotton cellulose using photoinitiation technique in the presence of the photoinitiator benzoin ethyl ether. Various parameters of the graft-copolymerization reaction, namely time, temperature, initiator, and monomer concentrations, were optimized using the grafting bath containing 10% methanol/acetone to dissolve the photoinitiator. The cotton sample, preswollen in sodium hydroxide, was subjected to grafting under optimized conditions. The preswollen samples showed higher graft add-on values at the equivalent monomer concentration. The moisture regain initially decreased at lower graft add-on levels and increased marginally with higher graft add-on. This behavior of the grafted substrate with respect to moisture regain has been explained.     

Mechanical and thermal properties of glycidyl methacrylate grafted cotton cellulose

UV-radiation-induced graft-copolymerization of cotton cellulose was carried out with glycidyl methacrylate (GMA) using ceric ammonium nitrate (CAN) as a photoinitiator as well as a chemical initiator. With increase in the graft add-on, breaking load and moisture regain of cotton decreased, so also its thermal stability. The fiber surface changes due to grafting were ascertained by X-ray diffraction and scanning electron microscopy. © 1995 John Wiley & Sons, Inc.     

Polymer deposition in sisal fibers: A structural investigation

Sisal (Agave sisalana) fibers were graft copolymerized with certain vinyl monomers (methyl acrylate, ethyl acrylate and methyl methacrylate) using gamma irradiation and ceric ammonium nitrate as initiation techniques. Examinations of the surface topology and the internal structure of the grafted fibers made by scanning electron microscopy. The results derived from the SEM observations on transverse sections of the grafted fibers were supplemented by information obtained by polarized light microscopy. Polymer was deposited not only on the surface of the fiber substrate, but also in the lumen, the middle lamellae, and throughout the cell wall network of the multicellular aggregates. The degree of polymer inclusion in the lumen (which is the most conspicuous of all the available internal sites) was found to depend on the percentage graft copolymer add-on, as well as on the previous history of the fiber (natural or chemically modified). The mechanical properties of the grafted fibers were investigated (by means of an Instron tensile tester).     

In situ polymerization of aniline on acrylamide grafted cotton

In this article, polyaniline (PANI)/cotton composite were prepared by in situ polymerization on the grafted cotton. First, acrylamide was grafted onto cotton cellulose using a radical graft polymerization process and some influencing factors were studied. Then polyaniline/cotton conductive composite fabrics were prepared by chemical in situ polymerization on the grafted cotton. The influences of the concentration of ammonium persulfate, aniline, hydrochloric acid, and the reaction time to the conductivity and K/S of composite fabric were studied. By contrasting, graft brought on an improvement of about one order of magnitude to the conductivity of composite fabric. The strength, TG, FTIR‐ATR, and SEM of prepared fabric were measured. The thermal stability and tear strength of composite fabric reduced, whereas PANI exhibited a rough but uniform, coherent PANI coating on surface of cotton fiber. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

The modification of wild silk fibres with methacrylamide

Wild silk and cultivated mulberry silk fibres have been graft copolymerised with methacrylamide, and the changes in the dyeing behaviour when dyeing with the levelling acid and milling acid dyes investigated. The tensile properties of the fibres and their durability during laundering have also been examined. The amount of the levelling acid dye adsorbed by all the fibres decreased with increasing polymer add-on, while the amount of milling acid dye adsorbed by the mulberry silk fibres was almost unchanged by the graft treatment. The breaking loads of the fibres were almost unchanged whereas rigidity of the fibres increased following graft treatment. The tensile properties of the grafted silk fibres were not diminished by laundering at polymer add-on levels greater than 50%.     

Photoinduced graft copolymerization of 2-hydroxyethyl methacrylate on cotton cellulose in the presence of triethyleneglycol dimethacrylate

The addition of a bifunctional monomer, triethylene glycol dimethacrylate (TEGDMA), to a grafting system containing 2-hydroxyethyl methacrylate (HEMA) and benzoin ethyl ether photoinitiator substantially increased the graft add-on of the unswollen and sodium hydroxide–swollen cotton cellulose. Grafting caused changes in the properties of the substrate such as moisture regain, the water of imbibition, and the dyeability with a direct and a reactive dye in accordance with the graft level. The observations have been explained in relation to structural changes in the grafted cotton. © 1994 John Wiley & Sons, Inc.     

Thermal behavior of cellulosic graft copolymers. II. Cotton grafted with binary mixtures of vinyl acetate and methyl acrylate

Thermal degradation of cotton, mercerized cotton, cotton grafted with vinyl acetate-methyl acrylate mixtures at different compositions, and mercerized cotton grafted with vinyl acetate–methyl acrylate mixture at a composition of 60 : 40 has been investigated using the techniques of thermogravimetric analysis (TGA) and differential thermal analysis (DTA) in nitrogen. The kinetic parameters E, n, and A have been obtained following several methods of thermogravimetric analyses. The mercerization shows a little effect upon thermic properties of cotton cellulose, making cotton thermally more stable. Graft copolymerization of vinyl acetate-methyl acrylate mixture makes cotton thermally less stable if the composition of the copolymer grafted is 100, 90, and 70 mol % VA, while in the case of cellulose graft copolymers with compositions of VA–MA of 80 : 20, 20 : 80, 5 : 95, and 0 : 100 the thermal stability is higher than that of original cotton. The thermal stability of the mercerized cotton grafted with vinyl acetate-methyl acrylate mixture with a composition of 60 : 40 depends on the percent grafting yield. The thermal stability of mercerized cotton grafted with the monomer mixture is higher than that of cotton grafted with that monomer mixture. The degradation of cellulose and cellulose graft copolymers is complex as is shown by DTA thermograms and kinetic parameters.     

Graft copolymerization of ϵ-Caprolactam onto Kevlar-49 fiber surface and properties of grafted Kevlar fiber reinforced composite

The anionic graft copolymerization of ϵ-caprolactam onto a Kevlar-49 fiber surface was carried out by using a metalation reaction in a dimethyl sulfoxide solution of sodium hydride. The effects of reaction conditions on the graft yield and on the tensile strength of the fiber have been investigated. Graft yield significantly increased with increasing metalation time, NaH concentration, and monomer concentration. The graft yield varied from 6 to 32% with reaction conditions. The tensile strength of the fiber depended predominantly on NaH concentration. The retained tensile strength was over 93% when the concentration of NaH was below 2.1 mmol/L per 0.5 g of Kevlar. The discontinuous Kevlar fiber reinforced composites were prepared by a blending/melt-pressing method. In thermomechanical and dynamic mechanical analyses, the relaxation peak of grafted Kevlar fiber/Nylon 6 composite film moved to higher temperatures, compared with the original Kevlar fiber/Nylon 6 composite film. The grafted Kevlar fiber reinforced Nylon 6 composite film exhibited mechanical properties superior to those of the original Kevlar fiber reinforced composite film. The higher thermal and mechanical properties were due to the effect of higher interfacial interaction between the grafted Kevlar fiber and matrix. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 99–107, 1997     

Graft-copolymerization of glycidyl methacrylate onto cotton cellulose

Glycidyl methacrylate was graft-copolymerized onto cotton cellolose using both photo-and chemical-initiation techniques using different initiators. The photoinitiators used were uranyl nitrate, ceric ammonium nitrate, and benzoin ethyl ether, whereas the chemical initiators used were ceric ammonium nitrate and potassium persulfate. Optimization of various parameters of grafting, viz., time, temperature, initiator, and monomer concentrations, was carried out. Ceric ammonium nitrate gave the maximum and almost identical values of graft add-on, by both grafting techniques, at equivalent cocentration of the monomer. Use of optimized conditions of ceric ammonium nitrate-photoinitiated grafting for sodium hydroxide-swollen substrate as well as for grafting baths incorporating acids enhanced the graft level. © 1994 John Wiley & Sons, Inc.     

Poly(methyl methacrylate-g-propylene oxide)

Summary Graft copolymers of poly(methyl methacrylate) with grafted branches of poly(propylene oxide) showed a single glass transition temperature and significant lowering of Tg when the percentage of grafted branches increased. Thermogravimetric analysis of graft copolymers showed a marked improvement in thermal stability when compared with poly(methyl methacrylate) homopolymer. Tensile properties of graft copolymers showed a decrease in tensile modulus and tensile strength but an increase in ultimate elongation with increase in grafted branches.This work was supported by Financiadora de Estudos e Projetos (FINEP), Conselho Nacional de Desenvolvimento Científi-co e Tecnológico (CNPQ) and Conselho de Ensino para Graduados e Pesquisa (CEG-UFRJ).     

Grafting of methyl methacrylate onto silk fibers initiated by tri-n-butylborane

Structural characteristics of the methyl methacrylate (MMA)-grafted silk fibers using tri-n-butylborane as an initiator were analyzed by infrared spectroscopy and differential scanning calorimetry (DSC), and their refractive index and tensile properties were measured. Graft polymerization was promoted by FeCl₃ pretreatment of the silk. The graft yield reached a maximum by the immersion in 4% FeCl₃ solution for 1 min at 25°C. The infrared spectrum of poly(MMA)-grafted silk fibers showed overlapped absorption bands of silk fibroin with the β structure and of the grafted MMA polymer. A grafted silk fiber with graft yield of more than 140% exhibited two endothermic peaks at 321°C and 396°C on the DSC curve, attributed to the thermal decomposition of silk fibroin and grafted poly(MMA) chain, respectively. Refractive index measurements suggested that the molecular orientation and the crystallinity of the silk fiber decreased with increasing graft yield. Electron photomicrographs showed that silk was coated by grafted PMMA. The tensile strength of the grafted silk decreased rapidly by the grafting even at a lower level.     

Graft copolymers of starch with mineral acid salts of dimethylaminoethyl methacrylate. Preparation and testing as flocculating agents

Mineral acid salts of dimethylaminoethyl methacrylate (DMAEMA) have been graft polymerized onto starch with ferrous ammonium sulfate–hydrogen peroxide initiation. The nitric acid salt was used in most reactions, and graft polymerizations were run in both water and aqueous–organic solvent systems. Increased monomer concentration in water led to an increase in both the percentage of poly(DMAEMA · HNO₃) in the graft copolymer (percent add-on) and the molecular weight of grafted branches. Variations in initiator concentration altered the percent add-on only slightly but affected the molecular weight of grafted polymer significantly. When swollen starch, in contrast with unswollen starch was used in graft polymerization reactions run in water, the product had a higher per cent add-on and a larger number of grafted branches of lower molecular weight. The efficiency of starch–poly(DMAEMA · HNO₃) graft copolymers as flocculants for diatomaceous silica increased with per cent add-on; however, variations in grafting frequency and graft molecular weight had less effect on the behavior of these materials as flocculants.     

Antibacterial,flame retardant,and physico‐chemical properties of cotton fabric graft copolymerized with a binary mixture of acrylonitrile and 4‐vinylpyridine

Modification of cotton fabric has been carried out through chemically induced graft copolymerization of binary mixture of acrylonitrile (AN) and 4‐vinyl pyridine (4‐VP) using ceric ammonium nitrate, (CAN) as initiator. Maximum percentage of grafting (151.28%) has been obtained at [4‐VP] = 0.376 mol L^?1 and [AN] = 1.221 mol L^?1, [CAN] = 0.0255 mol L^?1 and [HNO₃] = 0.9585 mol L^?1 in 25mL of water at 70°C in 180 min. Post quarternization and phosphorylation reactions of the grey and grafted cotton fabrics have been carried out to study their antibacterial and flame retardant properties respectively. The fabrics have been characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The physico‐chemical properties such as wettability, moisture regain, crease recovery and tensile strength of the grey and grafted cotton fabric have also been evaluated. The modified fabric has been shown to exhibit excellent antibacterial and flame retarding properties with improved physico‐chemical properties except for the mechanical properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40415.     

菠萝叶纤维与甲基丙烯酸甲酯接枝聚合条件优化及其共聚物性能表征

研究了硝酸铈铵为引发剂的氧化还原体系中,甲基丙烯酸甲酯（MMA）与菠萝叶纤维以水为介质的非均相接枝聚合反应。以纤维接枝率作为聚合效果评价指标,确定了优化的反应条件：铈离子浓度0.006 mol/L,氢离子浓度0.06 mol/L,MMA浓度0.4 mol/L,反应温度50 ℃,反应时间3 h,接枝率达到185 %。用扫描电镜（SEM）、X射线衍射（XRD）、红外光谱（FT-IR）、热重分析（TG）、纤维强力仪等分析MMA接枝前后纤维的结构和理化性质,结果显示,菠萝叶纤维接枝MMA后,改变了纤维分子原有的规整排列,纤维部分结晶区受到破坏,纤维呈松散状且更柔软,抗拉性能下降,而耐热性有所增强。同时,研究结果也显示了菠萝叶纤维MMA接枝率越高,则纤维的吸湿率越低,耐酸碱性能越强。     

Graft polymerization of vinyl acetate onto starch. Saponification to starch–g–poly(vinyl alcohol)

Graft polymerizations of vinyl acetate onto granular corn starch were initiated by cobalt-60 irradiation of starch-monomer-water mixtures, and ungrafted poly(vinylacetate) was separated from the graft copolymer by benzene extraction. Conversions of monomer to polymer were quantitative at a radiation dose of 1.0 Mrad. However, over half of the polymer was present as ungrafted poly-(vinyl acetate) (grafting efficiency less than 50%), and the graft copolymer contained only 34% grafted synthetic polymer (34% add-on). Lower irradiation doses produced lower conversions of monomer to polymer and gave graft copolymers with lower % add-on. Addition of minor amounts of acrylamide, methyl acrylate, and methacrylic acid as comonomers produced only small increases in % add-on and grafting efficiency. However, grafting efficiency was increased to 70% when a monomer mixture containing about 10% methyl methacrylate was used. Grafting efficiency could be increased to over 90% if the graft polymerization of vinyl acetate-methyl methacrylate was carried out near 0°C, although conversion of monomers to polymer was low and grafted polymer contained 40-50% poly(methyl methacrylate). Selected graft copolymers were treated with methanolic sodium hydroxide to convert starch–g–poly(vinyl acetate) to starch–g–poly(vinyl alcohol). The molecular weight of the poly(vinyl alcohol) moiety was about 30,000. The solubility of starch–g–poly(vinyl alcohol) in hot water was less than 50%; however, solubility could be increased by substituting either acid-modified or hypochlorite-oxidized starch for unmodified starch in the graft polymerization reaction. Vinyl acetate was also graft polymerized onto acid-modified starch which had been dispersed and partially solubilized by heating in water. A total irradiation dose of either 1.0 or 0.5 Mrad gave starch–g–poly(vinyl acetate) with about 35% add-on, and a grafting efficiency of about 40% was obtained. A film cast from a starch–g–poly(vinyl alcohol) copolymer in which homopolymer was not removed exhibited a higher ultimate tensile strength than a comparable physical mixture of starch and poly(vinyl alcohol).