Swelling-assisted graft copolymerization of 4-vinyl pyridine on poly(ethylene terephthalate) films using a benzoyl peroxide initiator

Graft copolymerization of 4-vinyl pyridine (4-VP) on poly(ethylene terephthalate) (PET) films using a benzoyl peroxide (Bz₂O₂) initiator was investigated under different conditions including polymerization time, temperature, monomer concentration, and initiator concentration. Dimethyl sulfoxide (DMSO) was used as swelling agent to promote the incorporation and the subsequent polymerization of 4-VP to PET films. Maximum percent grafting was obtained when the polymerization was carried for a period of two hours at 65°C. Increasing the monomer concentration from 0.2M to 0.8M and Bz₂O₂ concentration from 1.0×10⁻³M to 2.5×10⁻³M was accompanied by a significant enhancement in percent grafting. Monomer diffusion on PET films and its effect on the grafting yield were studied and intrinsic viscosities of grafted films were also measured. © 1996 John Wiley & Sons, Inc.     

4-Vinylpyridine and 2-hydroxyethylmethacrylate monomer mixture graft copolymerization onto poly(ethylene terephthalate) fibers using benzoyl peroxide

Summary Poly(ethylene terephthalate) (PET) fibers were grafted with 4-vinyl pyridine (4-VP) and 2-hydroxyethylmethacrylate (HEMA) using benzoyl peroxide (Bz₂O₂) as initiator in aqueous media. PET fibers were swelled in dichloroethane (DCE) for 2 h at 90 °C to promote the incorporation and the subsequent polymerization of 4-VP/HEMA onto PET fibers. Variations of graft yield with time, temperature, initiator concentration and monomer mixture ratio were investigated. The optimum initiator concentration was found to be 8×10^-3 mol/L. The maximum graft yield was obtained 280%. The optimum temperature and polymerization time was found to be 85 °C and 100 min. respectively. The rate of grafting was found to be proportional of the 1.5 and 0.3 powers of 4-VP/HEMA and Bz₂O₂ concentrations, respectively. The grafted PET fibers were characterized by thermo gravimetric analysis and scanning electron microscopy (SEM). Further changes in properties of grafted PET fibers such as water absorption capacity, intrinsic viscosity and diameter were determined. The dye ability of the PET fibers increased with an increase in grafting with diazo and basic dyes.     

Grafting of poly(ethylene terephthalate) fibers with methacrylic acid using benzoyl peroxide

The graft copolymerization of methacrylic acid onto poly(ethylene terephthalate) fibers, by the aid of benzoyl peroxide, have been investigated. The graft yield increased up to 85°C, and then decreased with the further increase in temperature. The maximum graft yield was obtained at benzoyl peroxide concentration of 4.0 × 10^?3 mol/L. The increase in the concentration of monomer was found to increase the graft yield. The change in the graft yield was followed by the experiments carried out using different water/solvent mixtures. Also, the change in the properties of polye (thylene terephthalate) fibers grafted with methacrylic acid such as moisture regain, density, and diameter were investigated.     

Solvent-assisted graft copolymerization of acrylamide on poly(ethylene terephthalate) films using benzoyl peroxide initiator

Graft-copolymerization of acrylamide (AAm) on poly(ethylene terephthalate) (PET) films using benzoyl peroxide (Bz₂O₂) initiator has been studied. Four organic solvents, namely, pyridine (Py), 1,2-dichloroethane (DCE), DEC/H₂O (20/80, v/v), and dimethyl sulfoxide (DMSO), were used as swelling agents. DMSO was found to be the most suitable swelling agent. Solvent inclusion in the films increased with increased length of solvent treatment time and temperature. Elevated temperatures had a greater effect on the inclusion of swelling agents than did the length of swelling. Variation of graft yield with the type of solvent, initiator concentration, monomer concentration, temperature, and polymerization time were also investigated. The graft yield increased in the order of toluene, benzene, DMSO. The optimum temperature for grafting was found to be 70°C. The graft yield was observed to increase with monomer concentration and polymerization time, then reached a plateau. The graft yield increased up to a certain Bz₂O₂ concentration, then decreased. © 1993 John Wiley & Sons, Inc.     

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.     

Adsorption of hexavalent chromium from aqueous solutions using 4-vinyl pyridine grafted poly(ethylene terephthalate) fibers

Summary Sorption of hexavalent chromium ions from aqueous solution by 4- vinyl pyridine (4-VP) grafted poly(ethylene terephthalate) (PET) fibers was studied. The Influences of adsorption time, pH of solution and Cr(VI) concentration on the adsorbed amount were investigated. 30 minutes of treatment time was found to be sufficient to reach equilibrium. pH 3.0 was found as the optimum pH value in the process. The maximum adsorption capacity of the material (k_s) was found to be 263.16 mg g^-1. It was found that the reactive fibers are stable and regenerable by acid or base without losing their activity.     

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 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     

Graft copolymerization of methyl methacrylate onto poly(ethylene terephthalate) fibers using thallium(III) ions as initiator

Graft copolymerization of methyl methacrylate onto poly(ethylene terephthalate) fibers was investigated in aqueous perchloric acid medium using thallium(III) ions as initiator. The rate of grafting was evaluated varying the concentrations of monomer, initiator, and acid and the temperature. The rate of grafting was found to increase with increase in monomer and initiator concentrations. The graft yield was found to increase with increase in the acid concentration up to 0.49 mL^?1, and beyond this concentration it was found to decrease. Increase in temperature resulted in increase in graft yield. From the Arrhenius plot the overall activation energy was found to be 3.76 kcal/mol. The effect of additives such as swelling agents, inorganic salts, different solvents, and inhibitors on graft yield was studied. A suitable kinetic scheme is proposed and a rate equation derived.     

Graft polymerization of 2-methyl-5-vinyl pyridine on poly(ethylene terephthalate) fibres using H2O2 as initiator

Graft polymerization of 2-methyl-5-vinyl pyridine (MVP) on unstretched poly(ethylene terephthalate) fibers (PET) using H₂O₂ as initiator was investigated under different conditions. The extents and rates of grafting, homopolymer and total conversion depended upon concentration of the initiator and the monomer as well as on the polymerization temparature. The extent and rate of grafting decreased as the H₂O₂ concentration increased from 6.82x10^?2 to 27.29x10^?2 mol · 1^?1. The same holds for the extents and rates of homopolymerization and total conversion. Whereas the extents and rates of grafting and total conversion increased significantly by increasing the MVP concentration from 0.162 to 0.648 mol.1^?1. Raising the polymerization temperature from 65 to 95°C was also accompanied by a significant enhancement in the extents and rates of grafting and total conversion. Stretching the PET fibres prior to grafting reduced appreciably the susceptibility of the fibres towards grafting, being dependent on the magnitude of stretching.     

Graft copolymerization of 2-methyl-5-vinyl pyridine to poly(ethylene terephthalate) fibres using a post-radiation technique

Radiation-induced grafting of 2-methyl-5-vinyl pyridine (MVP) to poly(ethylene terephthalate) fibers (PET) was investigated under a variety of conditions employing a post-radiation technique. Over a range of a total dose of 1–10 Mrad, increasing the total dose from 1 up to 3 Mrad was accompanied by a significant enhancement in the extent and rate of grafting. Further increase in the total dose caused a decrease. The same situation was encountered with respect to MVP concentration (5%–10%) and polymerization temperature (75°–90°C). A MVP concentration of 8% and a temperature of 85°C constituted the optimal. Addition of copper sulfate at a concentration of 0.05 mmole/l. offset grafting. The effect of the said parameters on homopolymerization occurring during grafting was also investigated.     

Radiation grafting of N,N-dimethylaminoethylmethacrylate onto poly(ethylene terephthalate)

Summary Radiation-induced graft polymerization of N,N-dimethylaminoethylmethacrylate (DMAEMA) from 50% solution in chloroform onto poly(ethylene terephthalate) (PET) was carried out by means of mutual γ-irradiation of polymer in presence of liquid or vapor phase monomer solutions (direct method), or by grafting of monomer from this liquid solution onto polymer preirradiated in air. It has been shown higher effectiveness of grafting by the direct method from vapor phase of monomer or by the preirradiation method as compared with direct grafting from liquid monomer solution. Grafting did not affect crystallinity, transparency and durability of the starting PET. Received: 18 November 1999/Revised version: 7 February 2000/Accepted: 8 February 2000     

Modification of pristine multiwalled carbon nanotube by grafting with poly(methyl methacrylate) using benzoyl peroxide initiator

Multiwalled carbon nanotube was successfully grafted with poly(methyl methacrylate) by free radical mechanism using benzoyl peroxide initiator. The reaction was carried out in situ, where the initiator and methyl methacrylate monomer generated the polymer‐free radical that was subsequently grafted to the surface of the pristine multiwalled carbon nanotube. The multiwalled carbon nanotube grafted poly(methyl methacrylate) (MWCNT‐g‐PMMA) were characterized using Fourier transform infrared, differential scanning calorimetry, thermogravimetric analysis, ¹³ C‐solid NMR spectroscopy, X‐ray photoelectron spectroscopy, and scan electron microscopy. From the result of the characterizations, the grafting of poly(methyl methacrylate) on to multiwalled carbon nanotube was confirmed, and a percentage grafting of 41.51% weight was achieved under optimized conditions with respect to the temperature and the amount of the initiator. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43270.     

Highly efficient interpenetrating polymerization of styrene and 4‐vinylpyridine with poly(ethylene terephthalate) using benzoyl peroxide

A polymerization method for the preparation of an interpenetrating network polymer with poly(ethylene terephthalate) is reported. Two types of monomer, styrene and 4‐vinylpyridine, were chosen as hydrophobic and hydrophilic representatives, respectively, in order to show the versatility of this polymerization method. The polymer‐immobilized poly(ethylene terephthalate) samples were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy and X‐ray photoelectron spectroscopy. The immobilization efficiency of styrene as a function of reaction temperature, monomer‐to‐initiator molar ratio, reaction time, addition of solvent, surface hydrophilicity and immersion in initiator was studied. The maximum immobilization percentage of styrene reaches 111%. The immobilization efficiency is proportional to polymer molecular weight and sample thickness. Based on these results, this strategy is shown to be an efficient, versatile method for preparing interpenetrating network polymers and can be used as a means to modify the structures and properties of polymeric substrates. © 2013 Society of Chemical Industry     

Kinetics of graft copolymerization of acrylamide and 2-hydroxyethylmethacrylate monomer mixture onto poly(ethylene terephthalate) fibers

Poly(ethylene terephthalate) (PET) fibers were grafted with acrylamide (AAm) and 2-hydroxyethylmethacrylate (HEMA) using benzoyl peroxide (Bz₂O₂) as initiator in aqueous media. PET fibers were swelled in dichloroethane (DCE) for 2 h at 90 °C to promote the incorporation and the subsequent polymerization of AAm/HEMA onto PET fibers. Variations of graft yield with time, temperature, initiator concentration and monomer mixture ratio were investigated. The optimum initiator concentration was found to be 10 mmol/L. The maximum graft yield was obtained (prep.) 273%. The optimum temperature and polymerization time were found to be 85 °C and 120 min, respectively. The rate of grafting was found to be proportional of the 1.39 and 0.37 powers of AAm/HEMA and Bz₂O₂ concentrations, respectively. The grafted PET fibers were characterized by FTIR spectroscopy and scanning electron microscopy (SEM). Further changes in properties of grafted PET fibers such as water absorption capacity and diameter were determined. The dyeability of the PET fibers increased with an increase in grafting with acidic and basic dyes.     

Photoinitiated surface grafting of synthetic fibers,III. Photoinitiated surface grafting of poly(ethylene terephthalate) fibers

Photoinitiated surface grafting of acrylic acid (AA), acrylamide (AM) and 4-vinyl pyridine (VP) onto poly(ethylene terephthalate) (PET) fibers (a commercial textile yarn) has been studied using benzophenone (BP) as photoinitiator. A continuous process as previously described has been applied, which involves presoaking of the PET yarn in a solution of initiator and monomer in acetone and UV irradiation in nitrogen atmosphere. The resulting grafted polymer on the fiber surface has been analyzed by ESCA, titration of carboxy groups (grafted AA), and dye absorption. The relative ESCA intensities (RI) of O1s/C1s and N1s/C1s are used as measure for grafted AA, AM and VP, respectively, after recording the RI-values for ungrafted fibers. For grafting with AA, the RI-values increased from 32.8% (background) to 48.6% after 20 s irradiation time. The amount of carboxy groups measured by titration increased from 0.045 to 0.106 mmol/m². Assuming an even coverage of grafted AA polymer, this means a grafted layer of 4.8 nm thickness. After grafting, the adsorption of the dye Crystal Violet (CV) from aqueous solution increased by about 3 times. With AM as monomer, the RI-values increased from 2.6 (background) to 14.8% and the adsorption of a direct dye Sirius Lichtbordo B-LL increased by about 6 times. With VP as grafted monomer, the RI-values increased from about 2.6 (background) to 5.1% and the adsorption of the direct dye increased by about 4 times.     

Graft polymerization of methyl methacrylate on poly(ethylene terephthalate) fibers using H2O2 as initiator

The presence of poly(ethylene terephthalate) (PET) fibers during polymerization of methyl methacrylate (MMA) using H₂O₂ as initiator resulted in a substantial, constant increase in the weight of the fibers after repeated extraction with acetone. Fractional precipitation curves of the extracted PET—MMA polymerization product and a physical mixture of PET and PMMA were different, indicating that the interaction of MMA with PET involved grafting. The magnitude of the latter enhanced considerably by increasing H₂O₂ concentration up to 30 mequiv/L, then decreased by further increasing H₂O₂ concentration. There was also an optimal temperature (80°C) for grafting; below or above this temperature, lower grafting was obtained. Similarly, carrying out the polymerization reaction at different pH values revealed that pH7 constituted the optimal. On the other hand, grafting increased upon increase of the methyl methacrylate concentration within the range studied (8–20%). Incorporation of Cu²⁺ or Fe³⁺ ions in the polymerization medium caused a decrement in grafting, irrespective of the metallic ion concentrations. Using methylene chloride as a swelling agent for the fibers failed to enhance the susceptibility of the latter toward grafting. On the contrary, tetrachloroethane was quite promising in this regard. The homopolymer formed during grafting was also reported.     

Radiation grafting to poly(ethylene terephthalate) fibres

Polyethylene terephthalate (PET) monofilaments were grafted with styrene in methylene chloride solution using both the mutual and preirradiation methods. Good yields were obtained, the grafted fibres were dissolved and the graft copolymer and both homopolymers separated by various techniques. The graft copolymers were hydrolysed with potassium hydroxide in benzyl alcohol to destroy the PET backbone. The molecular weights were determined by osmometry. The G values of grafted side chains were 0.57 and 0.10 per 100 eV for the mutual and preirradiation methods, respectively. The corresponding fractions of PET grafted were 0.24 and 0.11. Less than 4% homopolymer was produced by either method. The yields contrast with radical yields measured by e.s.r. of only 0.025. It is suggested that the high grafting yields are due to the methylene chloride facilitating the accessibility of the monomer to the active sites created by the radiation rather than by the increased yields of radicals by chain transfer. Chlorine, for example, did not lead to increased yields even in the presence of methylene chloride. Presumably, in the mutual grafting system, radicals are available for grafting, which are too labile to be detected by e.s.r. In the case of the preirradiation method, the yields are also higher than the radical yields. This may be due to a regenerative chain transfer mechanism.