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1.
Premamoy Ghosh Ganeschandra Pal 《Journal of polymer science. Part A, Polymer chemistry》1997,35(9):1681-1687
Polymerization of methyl methacrylate (MMA) was kinetically studied under photo condition using near UV visible light at 40°C and employing morpholine (MOR)–chlorine (Cl2) charge transfer (C-T) complex as the photoinitiator. The rate of polymerization (Rp) was dependent on morpholine/chlorine mole ratio; the 1 : 2 (MOR–Cl2) C-T complex acted as the latent initiator complex, C, which underwent further complexation with the monomer molecules to give the actual initiator complex, I. Using 1 : 2 (MOR-Cl2) C-T complex as the latent initiator, the initiator exponent evaluated for bulk photopolymerization of MMA was 0.071 and monomer exponent determined from studies of photopolymerization in benzene diluted system was 1.10. Benzoquinone behaved as a strong inhibitor and the polymers tested positive for the incorporation of chlorine atom end groups. Polymerization followed a radical mechanism. Kinetic nonideality as revealed by low (≪0.5) initiator exponent and a monomer exponent of greater than unity were explained in terms of primary radical termination effect. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 1681–1687, 1997 相似文献
2.
Subasini Lenka Padma L. Nayak 《Journal of polymer science. Part A, Polymer chemistry》1982,20(8):2097-2103
Polymerization of MMA was carried out in the presence of visible light (440 nm) with the use of γ-picoline-bromine charge transfer complex as the initiator. The rate of polymerization Rp increases with increasing monomer concentration and the monomer exponent was computed to be unity. The rate of polymerization increases with increasing initiator concentration. The initiator exponent was computed to be 0.5. The reaction was carried out at three different temperatures and the overall activation energy was calculated to be 4.5 kcal/mol. The polymerization was inhibited in the presence of hydroquinone. Kinetic and other evidence indicates that the overall polymerization takes place by a radical mechanism. 相似文献
3.
Munmaya K. Mishra Subasini Lenka Padma L. Nayak 《Journal of polymer science. Part A, Polymer chemistry》1981,19(10):2457-2464
Photopolymerization of MMA was carried out with quinaldine–bromine (QN–Br2) and lutidine–bromine (LU–Br2) charge-transfer complexes as initiators. The rate of polymerization Rp increased with rising monomer concentration and the monomer exponent was computed as unity. At first the rate of polymerization accelerated and then reduced as the initiator concentration was increased. The initiator exponent was 0.5. The reaction was carried out at three different temperatures and overall activation energy was calculated at 4.0 kcal/mol. The kinetic data and other evidence indicate that the overall polymerization takes place in a radical mechanism. A suitable mechanism is suggested. 相似文献
4.
The photopolymerization of MMA in visible light was studied at 45°C using IC13 as the photoinitiator. The initiator exponent was found to be 0.16 and the monomer exponent varied between 1.0 to 1.50, depending on the nature of the solvent. Analysis of the data revealed that the polymerization was induced by a free radical mechanism. Nonideality of the kinetics was explained on the basis of 1) Monomer-dependent chain initiation and 2) Initiator-dependent chain termination via degradative initiator transfer. 相似文献
5.
Photopolymerization of MMA in visible light was studied at 40 using THF-SO2 complex as the photoinitiator. Initiator exponent was 0.19 and monomer exponent lay between 1.0 and 1.5, depending on thenature of solvent. Analysis of kinetic and other data indicate that the polymerization proceeds by a radical mechanism and termination is initiator dependent. Chain termination via degradative chain (initiator) transfer appears to be significant feature. 相似文献
6.
Premamoy Ghosh Samir Biswas Utpal Niyogi 《Journal of polymer science. Part A, Polymer chemistry》1986,24(5):1053-1063
Photopolymerization of methyl methacrylate (MMA) in visible light was studied at 40°C using Rhodamine 6G—Benzoyl peroxide combination as photoinitiator. The photopolymerization proceeds by a free radical mechanism and the radical generation process occurs by an initial complexation reaction between the initiator components. Kinetic data indicated a lower-order dependence of Rp on initiator concentrations (initiator exponent < 0.5). Initiator-dependent chain termination was significant along with the bimolecular mode of chain termination. 相似文献
7.
The photopolymerization of methyl methacrylate (MMA) in visible light was studied at 40°C using the acridone-bromine (acridone-Br2) combination as the photoinitiator. The polymerization was found to proceed via a free radical mechanism, and the radical generation process was considered to follow an initial complexation reaction between monomer and each initiator component (acridone and Br2), followed by further interaction between these two initiator-monomer complexes. Kinetic data indicated a lower-order dependence of R on initiator concentrations (initiator exponent < 0.5). Initiator-dependent chain termination was signifi-cant along with the usual bimolecular mode of chain termination. The monomer exponent varied from about 1.00 to 2.00, depending on the nature of solvents used. The nonidealities in this system were also analyzed. 相似文献
8.
Premamoy Ghosh Amar Nath Banerjee 《Journal of polymer science. Part A, Polymer chemistry》1977,15(1):203-218
The polymerization of MMA was kinetically studied in the presence of visible light (using a 125-W high-pressure mercury vapor lamp with fluorescent coating, without a filter), a THF—bromine charge-transfer complex being used as the photoinitiator. The initiator exponent was 0.5 in bulk polymerization. The monomer exponent varied from about 1.2 to about 2.5, depending on the nature of the solvent used; the initiator exponent also varied in diluted systems, depending on the nature and proportion of the solvent, the variation being from a value of 0.5 in bulk system to zero or almost zero at about 25% (v/v) solvent concentration. Other kinetic parameters, viz., kp2/kt and the activation energy for polymerization, were determined and are reported. Kinetic and other evidence indicates that the photopolymerization takes place by a radical mechanism and termination is bimolecular in nature in bulk systems; in dilute systems, termination by initiator complex assumes predominance, particularly at high solvent concentrations (≥25% v/v). 相似文献
9.
Premamoy Ghosh Partha Sarathi Mitra 《Journal of polymer science. Part A, Polymer chemistry》1975,13(4):921-930
Polymerization of MMA was carried out in presence of visible light (440 nm), quinoline-bromine charge-transfer complex being used as the photoinitiator. The initiator exponent was observed to be 0.5 up to 0.014 M initiator concentration; when chloroform was used as the solvent, the monomer exponent was found to be unity. The polymerization was inhibited in presence of hydroquinone but little inhibitory effect was observed in the presence of air. An average value of k2p/kt for this photopolymerization system was found to be (1.08 ± 0.22) × 10-2. Kinetic and other evidence indicates that the overall polymerization takes place by a radical mechanism. 相似文献
10.
Photopolymerization of methylmethacrylate using triethylamine-benzoylperoxide redox initiator system
Photopolymerization of MMA was studied kinetically at 35° using TEA-BZ2O2 redox system as initiator. The initiator exponent is 0.34 but the monomer exponent depends on the solvent. Solvents (acetonitrile, pyridine and bromobenzene) giving negative or fractional monomer exponent show a rate enhancing effect through actively influencing the initiation step; benzene and chloroform give first order dependence of rate on [monomer] and behave as normal (inert) diluents. Initiation of polymerization takes place through radicals generated by photodecomposition of TEA-BZ2O2 complex formed in situ, the radical generation step being solvent or monomer dependent. Kinetic non-idealities are interpreted in terms of significant initiator dependent termination via degradative chain transfer. 相似文献
11.
Premamoy Ghosh Tapas Kumar Ghosh 《Journal of polymer science. Part A, Polymer chemistry》1984,22(10):2295-2303
Photopolymerization of methyl methacrylate (MMA) was studied at 40°C using a macromolecular C.T. Complex between poly(N-vinyl carbazole) and bromine, expressed in brief as (PNVC–Br2) complex, as the photoinitiator. Initiator exponent was 0.40 for [PNVC–Br2] ≤ 2.5 × 10?3 mol L?1 and practically zero for [PNVC–Br2] > 2.5 × 10?3 mol L?1. Monomer exponent in different diluent systems such as benzene, carbon tetrachloride, and acetone was close to 1.0. Low initiator exponent (<0.5) is explained on the basis of an initiator-dependent termination mechanism, in addition to the usual bimolecular termination. Analysis of kinetic data indicates that the initiator-dependent termination is primarily due to degradative initiator transfer and that due to primary radicals is considered inconsequential in view of monomer exponent being close to unity. The non-ideal termination process assumes over-whelming prominence at high [PNVC–Br2]. 相似文献
12.
《Polymer Photochemistry》1983,3(2):109-118
Photoinduced graft copolymerisation of methyl methacrylate onto cellulose was investigated using a pyridine-bromine (Py-Br2) charge-transfer complex as initiator. The graft-on percentage increases with increasing initiator and monomer concentrations in the initial stages and thereafter it decreases. The initiator exponent was computed to be 0·5. The reaction was carried out at three different temperatures and the overall activation energy has been computed. The kinetic data and other evidence indicate that the overall polymerization takes place by a radical mechanism. A suitable kinetic scheme has been suggested. 相似文献
13.
Premamoy Ghosh Ganeschandra Pal 《Journal of polymer science. Part A, Polymer chemistry》1998,36(12):1973-1979
Photopolymerization of the vinyl monomer (M) of methyl methacrylate (MMA) was kinetically studied by using near-UV/visible light at 40°C and employing a morpholine (MOR)–sulfur dioxide (SO2) charge-transfer (C-T) complex as the photoinitiator. The rate of polymerization (RP) was found to be dependent on the morpholine: sulfur dioxide mole ratio; the 1 : 2 (MOR–SO2) complex acted as the latent initiator complex C which underwent further complexation with the monomer molecules to give the actual initiating complex I. Using the 1 : 2 (MOR–SO2) C-T complex as the latent initiator, the observed kinetics may be expressed as RP [MOR–SO2]0.27[M]1.10. Benzoquinone behaved as a strong inhibitor. Polymers obtained tested positive for the incorporation of a sulphonate-type end group. Polymerization followed a radical mechanism. Kinetic nonideality as revealed by a low initiator exponent and monomer exponent of greater than unity was explained on the basis of a prominent primary radical termination effect. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1973–1979, 1998 相似文献
14.
R. S. Tewari Anita Bajpai A. K. Srivastava 《Journal of polymer science. Part A, Polymer chemistry》1985,23(9):2405-2411
The thermal polymerization of methyl methacrylate [MMA] was carried out using ylide (4-picolinium 4-chloro phenacyl methylide) as an initiator. The rate of polymerization (Rp) increases with increasing monomer and initiator concentrations; The exponent value has been computed to be 1 ± 0.02 and 0.5, respectively. The reaction was carried out at four different temperatures and the overall activation energy has been computed to be 16.01 kcal/mol. The polymerization was inhibited in the presence of hydroquinone as a radical scavanger. Kinetic studies indicates that the overall polymerization takes place by a radical mechanism. 相似文献
15.
Premamoy Ghosh Partha Sarathi Mitra 《Journal of polymer science. Part A, Polymer chemistry》1976,14(4):993-1004
Polymerization of MMA was done in the presence of visible light (440 nm) with the use of N-bromosuccinimide (NBS) as the photoinitiator. The initiator exponent and intensity exponent were 0.5, and the monomer exponent was found to be unity. The polymerization was inhibited in the presence of hydroquinone. The average kp2/kt for this photopolymerization system was found to be 0.296 × 10?2 and the activation energy of photopolymerization was 4.67 kcal/mole. Kinetic and other evidence indicate that the overall polymerization takes place by a radical mechanism. With NBS as the photoinitiator, the order of polymerizability at 40°C was MMA, EMA ? MA ? VA, and styrene could not be polymerized under similar conditions. 相似文献
16.
Pranab Kumar Som Amar Nath Banerjee 《Journal of polymer science. Part A, Polymer chemistry》1993,31(4):1007-1012
Isatoic anhydride (IA) alone did not initiate photopolymerization of methyl metacrylate (MMA) at 40°C when exposed to visible light for about 180 min. But IA, when used in combination with bromine (Br2) as the initiator, initiated the photopolymerization of MMA readily under the same conditions. This behavior was explained by the formation of a donor-acceptor type of complex between IA and Br2 in the presence of MMA. The polymerization was found to proceed via a free radical mechanism and the radical generation process was considered to follow an initial complexation reaction between the initiator components and monomer. The complex initiator showed nonideal kinetics for the present system (initiator exponent < 0.5) and was analyzed. The monomer exponents varied from 0.83 to 1.15 normally depending on the nature of solvent used. Initiator-dependent chain termination was significant as well as the bimolecular mode of chain termination. © 1993 John Wiley & Sons, Inc. 相似文献
17.
C. Namasivayam P. Natarajan 《Journal of polymer science. Part A, Polymer chemistry》1983,21(5):1385-1400
The kinetics of photopolymerization reactions of acrylamide initiated by copper (II)–bis(amino acid) chelates with amino acids glutamic acid, serine, or valine were studied at 30°C. The extent of monomer conversion increases with increased initiator concentration and falls off after reaching a maximum. Analysis of the results shows that for lower concentrations of the initiator, the rate of monomer disappearance is proportional to light absorption fraction f[monomer] and the square root of the intensity. At higher concentrations of the initiator, the rate of monomer disappearance is proportional to Fε/[initiator]1/2; the monomer exponent is 1.5 and the intensity exponent 0.5. Mutual termination of the radicals is proposed at lower concentrations of the initiator; at higher concentrations of the initiator termination of the initiator radical by the copper (II) complex along with mutual termination occurs. The initiator radical species is identified from flash photolysis studies of these complexes as the Cu(I)-coordinated radical. The effect of pH on the monomer conversion is explained. The data indicate a free-radical mechanism of polymerization and a reaction scheme is proposed for the polymerization reactions. 相似文献
18.
Premamoy Ghosh Partha Sarathi Mitra 《Journal of polymer science. Part A, Polymer chemistry》1977,15(7):1743-1758
Photopolymerization of MMA was carried out at 40°C in diluted systems by use of quinolinebromine (Q–Br2) charge-transfer complex as the initiator and chloroform, carbon tetrachloride, chlorobenzene, dioxane, THF, acetone, benzene, toluene, quinoline, and pyridine as solvents. The results showed variable monomer exponents ranging from 1 to 3. For chloroform, carbon tetrachloride, and chlorobenzene, the monomer exponent observed was unity; for other solvents used, the value of the same exponent was much higher (between 2 and 3). Initiation of polymerization is considered to take place through radicals generated in the polymerization systems by the photodecomposition of (Q–Br2)–monomer complex (C) formed instantaneously in situ on addition of the Q–Br2 complex in monomer. The kinetic feature of high monomer exponent is considered to be due to higher order of stabilization of the initiating complex (C) in presence of the respective solvents. In the presence of the retarding solvents, very low or zero initiator exponents were also observed, depending on the nature and concentration of the solvents used. The deviation from the square-root dependence of rate on initiator concentration becomes higher at high solvent and initiator concentrations in general. This novel deviation is explained on the basis of initiator termination, probably via degradative chain transfer involving the solvent-modified initiating complexes and the propagating radicals. 相似文献
19.
Photopolymerization of MMA in visible light was studied at 40°C using acridone as the photoinitiator. The polymerization was found to proceed via a free radical mechanism and the radical generation process was considered to follow an initial complexation reaction between monomer and acridone. Kinetic data indicated a lower order dependence of Rp on the initiator concentration (initiator exponent < 0.5). Initiator-dependent chain termination was significant along with the usual bimolecular mode of chain termination. The monomer exponent varied from about 1.0 to 1.5, depending on the nature of the solvent used. The nonidealities in this case were also analyzed. 相似文献
20.
Free radical photopolymerization of methyl methacrylate (MMA) in visible light was studied at 40°C using sulfur dioxide-halogen (Cl2, Br2, and I2) combinations as photoinitiators. Of the three SO2/halogen systems, only the SO2/Br2 combination formed an interesting initiating system due to 1:1 complexation between the two components resulting in pronounced enhancement of the rate of photopolymerization over those produced by each of the initiator components when used as a lone photoinitiator. Photopolymerization of MMA induced by (SO2-Br2) complex (1:1) as the photoinitiator exhibited a low initiator exponent value, 0.26, and a monomer exponent value of 1.5. Kinetic nonidealities were explained on the basis of (a) monomer-dependent chain initiation and (b) significant initiator-dependent chain termination along with the usual bimolecular mode of chain termination. 相似文献