Grafting vinyl monomers onto cellulose. I. Graft copolymerization of methyl methacrylate onto cellulose using quinquevalent vanadium ion

Graft copolymerization of methyl methacrylate on cellulosic materials with the use of quinquevalent vanadium as an initiator was studied. Increase of V⁵⁺ion concentration up to 0.0025 mole/liter increases graft yield, and with further increase of the initiator the graft yield decreases. The graft yield increases with increase of monomer concentration. The increase of acid concentration is accompanied by decrease of graft yield. A measurable increase in graft yield was observed with increase in temperature from 65 to 75°C. The graft yield is medium and substrate dependent. A suitable kinetic scheme has been pictured and a rate equation has been derived.     

Graft polymerization of methyl methacrylate onto nylon 6 using pentavalent vanadium as initiator

Pentavalent vanadium ion (V^v)-induced graft polymerization of methyl methacrylate onto nylon 6 was investigated under a variety of conditions. Increasing the V^v-concentration up to 2 mmol/l was accompanied by an enhancement in grafting; the latter was not affected by further increase in V^v-concentration. Unlike grafting, the homopolymer and total conversion tended to increase by increasing V^v concentration. The graft yield enhanced significantly when the MMA-concentration was increased up to 3% further increase in MMA-concentration had no effect on grafting. Raising the polymerization temperature from 50° up to 70°C caused a significant increase in the rates of grafting, homopolymerization and total conversion. Using a solvent-water mixture as medium for polymerization affected considerably the magnitude of grafting. While using methyl alcohol, ethyl alcohol and acetone at any ratio in the solvent-water mixture resulted in decreased grafting, using an isopropyl alcohol-water mixture up to a ratio of 25 : 75 gave rise to increased grafting.     

Graft copolymerization of nylon 6 with methyl methacrylate using dimethylaniline/Cu2+ ion system

The ability of dimethylaniline (DMA)/Cu²⁺ ion initiator to induce grafting of methyl methacrylate (MMA) onto nylon 6 was investigated under a variety of conditions. It was found that the graft yield is dependent on the concentration of the Cu²⁺ ion, of DMA, and of MMA. While the graft yield increases as the monomer concentration increases, there are optimal concentrations of DMA and Cu²⁺ ion. Below or above these concentrations, lower grafting occurred. The type of cupric salt also affects grafting to varying degrees. While the presence of CuSO₄ and Cu(NO₃)₂ accelerates grafting, the presence of CuCl₂ offsets the reaction. Increasing the reaction temperature and reaction time favorably influences grafting. Addition of acetic acid enhances grafting, whereas formic acid decreases grafting. Preswelling of nylon with formic acid leaves the susceptibility of nylon toward grafting practically unaltered. Studies of the copolymerization reaction was not confined to the graft yield but was extended to homopolymer formation and total conversion.     

Grafting of vinyl monomers onto nylon-6. 1. Graft copolymerization of acrylamide onto nylon-6 using trivalent manganese as initiator

The use of trivalent manganese to initiate graft-copolymerization of acrylamide onto nylon-6 has been investigated. The rate of grafting has been determined by varying monomer, manganese(III), temperature and solvent mixtures. The graft yield increases with increasing monomer concentration up to 0.8 M and with further increase of monomer concentration the graft yield decreases. The percentage of grafting increases with managanese (III) ion concentration up to 5.25 × 10^?3 M and thereafter it decreases. The rate of reaction depends on temperature. Among the solvent composition studied, a water/solvent mixture containing 25% of the solvent seems to constitute the most favourable medium for grafting and with further increase of solvent composition, the graft yield decreases.     

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     

Graft copolymerization onto rubber. VII. Graft copolymerization of methyl methacrylate onto rubber using potassium peroxydisulfate catalyzed by silver ion

The graft copolymerization of methyl methacrylate onto natural rubber (NR) was carried out varying the concentration of monomer, initiator, thiourea, and silver nitrate over a wide range. The grafting reaction was temperature-dependent. From the Arrhenius plot, the overall energy of activation was computed. A suitable reaction scheme and rate expression for the rate of polymerization was suggested.     

Graft copolymerization of mixtures of acrylic acid and acrylamide onto polypropylene film

Liquid phase ultraviolet irradiation in the presence of benzophenone as a photosensitizer and barium hydroxide as a pH controller were used to graft the mixtures of acrylic acid and acrylamide to a polypropylene surface. The surface of the grafted polypropylene samples were characterized by Fourier transform infrared spectroscopy‐attenuated total reflectance, electron spectroscopy for chemical analysis, scanning electron microscopy, and a contact angle meter. The pH value of the reaction medium that produced the graft with equal molar ratio was found to be ∼ 3.77. The optimal reaction condition was found at a monomer feed of 25%, a reaction time of 30 min, and a benzophenone concentration of 1%. Surface tension of the samples increased to a value of 40 dyn cm⁻¹ due to the graft of the hydrophilic monomers. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 251–256, 1999     

Graft copolymerization of acrylamide onto cellulose in presence of comonomer using ceric ammonium nitrate as initiator

The graft copolymerization of acrylamide (AAm) and ethylmethacrylate (EMA) monomers onto cellulose has been carried out using ceric ammonium nitrate (CAN) as initiator in presence of nitric acid at (25 ± 1)°C and varying feed molarity from 7.5 × 10^?2 mol dm^?3 to 60.0 × 10^?2 mol dm^?3 at fixed feed composition (f_AAm = 0.6). The graft yield (%G_Y) has shown a linear increasing trend upto a feed molarity of 37.5 × 10^?2 mol dm^?3. The composition of grafted copolymer chains was found to be constant (F_AAm = 0.56) during feed molarity variation but shown variations with feed composition (f_AAm) and reaction temperature. The grafting parameters have shown increasing trends up to 7.5 × 10^?3 mol dm^?3 concentration of ceric (IV) ions and decreased on further increasing the concentration of ceric (IV) ions beyond 7.5 × 10^?3 mol dm^?3. The IR and elemental analysis data were used to determine the composition of grafted chains (F_AAm) and reactivity ratio of acrylamide (r₁) and ethylmethacrylate (r₂) comonomers. The reactivity ratio for acrylamide (r₁) and ethylmethacrylate (r₂) has been found to be 0.7 and 1.0 respectively, which suggested for an alternate arrangement of average sequence length of acrylamide (mM?₁) and ethylmethacrylate (mM?₂) in grafted chains. The rate of graft copolymerization of comonomers onto cellulose was found to be proportional to square concentration of comonomers and square root to the concentration of ceric (IV) ions. The energy of activation (ΔEa) of graft copolymerization was found to be 9.57 kJ mol^?1 within the temperature range of 20–50°C. On the basis of experimental findings, suitable reaction steps have been proposed for graft copolymerization of selected comonomers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2546–2558, 2006     

Graft copolymerization of acrylamide onto bamboo rayon and fibre dyeing with acid dyes

Bamboo is considered to be an important biopolymer with useful applications in various fields including textiles. It is a renewable natural resource of cellulosic nature and it originates from grass family. It gives maximum biomass per unit area and time. In general, cellulosic fibres do not have acid dyeability as those of polyamide fibres. Hence, it is difficult to dye such fibres, unless modified, with acid dyes which are relatively cheaper than the direct class of dyes. In the current study, the bamboo rayon fabric was grafted with acrylamide using potassium persulphate (KPS) as an initiator. The grafting conditions were optimized in terms of temperature, time, initiator and monomer concentrations. The grafted product was characterized using FTIR, TGA, SEM and analyzed for textile properties like moisture regain and yellowness index. The ungrafted and grafted fabrics were dyed using acid dyes and tested for colour strength and fastness properties. An increase in the dyeability of the order of 150?C230% was observed on grafting of bamboo rayon. The distinct improvement in moisture regain of the grafted fabrics was also observed, which is due to increase in the polarity of the fibres. Hence, better comfort can be expected out of such fabrics during summer. The bamboo rayon which is otherwise not dyeable with acid dyes, can be rendered acid dyeable by grafting technique.     

Graft copolymerization of polyacrylonitrile (PAN) onto nylon 6/nylon 66 and simultaneous homopolymerization: A comparative study. II

The kinetics of graft copolymerization of polyacrylonitrile (PAN) onto nylon 6/nylon 66 and the simultaneous homopolymerization initiated by potassium peroxomonosulfate (PMS)–ascorbic acid (H₂A) redox systems were studied separately. Various kinetics parameters were evaluated and analyzed to have a comparison among the systems. The occurrence of simultaneous homopolymerization was evident through rate parameters. When the backbone was changed, the following order was observed for grafting efficiency: polyester (PET) > nylon 6 ? nylon 66. © 1995 John Wiley & Sons, Inc.     

Grafting vinyl monomers onto nylon 6. VI. Graft copolymerization of methyl methacrylate onto nylon 6 using acetylacetonate complex of Mn(III), Co(III), and Fe(III)

The graft copolymerization of methyl methacrylate onto nylon 6 using metal complexes of Mn³⁺, Co³⁺, and Fe³⁺ as initiators was studied. The rate of polymerization, R_p, increased with increasing complex concentrations in the initial stages; but it decreased upon further increase of complex concentrations. With increasing monomer concentrations, the rate of polymerization increased progressively. The graft yield increased with increaing temperature within the range 60–75°C. A suitable kinetic scheme is presented and rate equations are derived.     

Photo-induced graft copolymerization. XV. Graft copolymerization of methyl methacrylate onto nylon-6 using erythrosin as photoinitiator

The photo-induced graft copolymerization of methyl methacrylate onto nylon-6 was investigated using erythrosin as the photoinitiator. The systems were buffered with phosphate citrate buffer (Na₂HPO₄/citric acid). The graft copolymerization was carried out within the temperature range of 35–50°C and from the corresponding Arrhenius plot, the energy of activation was evaluated. The effect of monomer, initiator, ascorbic acid, etc. on the graft yield has been investigated. Further, the effect of solvent on the rate of grafting has been investigated and the chain transfer constant (C_s) of the solvent has been evaluated. The kinetic data and other events indicate that the overall polymerization takes place by a radical mechanism. A suitable mechanism has been suggested and rate expressions have been derived.     

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.     

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.