摘要:

The graft copolymerization of methyl methacrylate (MMA) onto native and reduced Indian Chokla wool fibers was studied in aqueous solution using an acetylacetonate complex of Fe(III). Perchloric acid was found to catalyze the reaction. The rate of grafting was investigated by varying the concentration of the monomer and the complex, the acidity of the medium, and the solvent composition of the reaction medium. The graft yield increases with increasing concentration of the initiator and with increasing temperature. An increase of monomer concentration up to 0.5634 mol/L and of the HClO4 concentration up to 0.01 mol/L increases the graft yield. Reduced and oxidized wools were found to be better substrates than untreated, esterified, cross-linked, and trinitrophenylated wools. Among the various monomers studied, MMA was found to be the most active. A suitable kinetic scheme is proposed. From the activation energy data, average molecular weight, and spectral studies, the reactivity of -SH groups, and the extent of chain transfer is ascertained.

ISSN:0022-233X    

DOI:10.1080/00222338408056570

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Dilute solution data on poly[2-methoxy-4,6-di-(p,p′-isopropyl-idene diphenyloxy)-s-triazine] have been analyzed by the Ptitsyn-Eizner theory. The rigidity parameter λ has been estimated. λ varies with the nature of the solvent. The temperature dependence of λ has also been investigated. The parameter λ has been compared with other polymers containing “long bonds.”

ISSN:0022-233X    

DOI:10.1080/00222338408056571

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The thermodynamic formation constants of N-(alkyl)-2- and/or 3-mercaptoacetamides complexes with dimethyl-, diethyl-, and n-dibutyltin(IV) cations have been determined potentiometrically in a dioxane-water mixture (75% v/v) at 30 ± 0.1°C in μ = 0.1 M NaCl using the Irving-Rossotti method and refined by the least-squares method. The basicity of the ligands follows the order C2H5NHCOCH2SH > n-C3H7NHCOCH2SH > n-C4HgNHCOCH2SH > C2H5NHCOCH2CH2SH > n-C3H7NHCOCH2CH2SH > n-C4Hg- NHCOCH CH SH. For each ligand the stability order of dialkytin(IV) complexes decreases as follows: [Me2Sn(IV)]2+>[Et Sn(IV)]2+> [n-Bu2Sn(IV)]2+.This order is consistent with the group electronegativities of [R2Sn(IV)]2+cations calculated from Sanderson's electronegativity scale.

ISSN:0022-233X    

DOI:10.1080/00222338408056572

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Powdered poly(N-carboxy α-amino acid anhydride) materials were treated at temperatures of 50, 100, 150, and 200°C under a pressure of 150 kg/cm2. A number of hot-pressed materials showed simultaneous fusion and contraction in volume. The fusion temperature of the hot-pressed materials was generally lower than the true melting point of the powdered materials at atmospheric pressure (determined with a Differential Scanning Calorimeter). The hot-pressed materials had high rigidity and transparency. The in vitro-in vivo degradation of hot-pressed materials was also investigated. The homo- and copoly(α-amino acid) materials used in this study were scarcely degraded, though debenzylated t e rpolymers such as β-benzyl-L-aspartate/aspartic acid/L-leucine and γ -benzyl-L- glutamate/glutamic acid/L - leucine we re significantly degraded in both the in vitro and in vivo experiments. It was found that the in vivo degradation profile of hot-pressed terpolymer materials corresponds relatively well to degradation with 0.01% trypsin.

ISSN:0022-233X    

DOI:10.1080/00222338408056573

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The enzyme and nonenzyme hydrolyses of the end ester group in polyethylene glycol (PEG) esters were studied. The end monoester in PEG ester is known to be easily hydrolyzed by alkaline or acidic solution. 2-Methyl-ω-benzoyloxypoly(oxy-1,2-ethanediyl)(Bz-PEG) and 2-methyl-ω-4-nitrobenzoyloxypoly(oxy-1,2-ethanediyl) were found to be hydrolyzed by lipase and esterase in Tris buffer solution (pH 7.7) but 2-methyl-ω-acetoxypoly(oxy-1,2-ethanediyl) was not. The parameters of enzyme reaction in the hydrolysis of ester bonds in Bz-PEG by esterase were estimated to be as follows: Vmax= 6.09 × 10−7mol/dm3.s, Km= 7.63 × 10−4mol/dm3.

ISSN:0022-233X    

DOI:10.1080/00222338408056574

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

A survey is made of the present knowledge about the kinetics and mechanism of the radical cyclopolymerization of dimethyl diallyl ammonium chloride which results in soluble, strong cationic poly-electrolytes. The kinetic analysis, taking into consideration nearly complete cyclization, a linear increase of kp /kt, 0.5 with [M], and different mechanism of initiation depending on the nature of the initiator, leads to rate equations which fit the experimental data well. Initiation with S2O82- has the following peculiarities: formation of primary radicals by redox reaction with chloride ions and interaction with the monomer cation, additional termination by chlorine atoms, and an experimental chain transfer constant to monomer which includes transfer to monomer and termination by chlorine radicals.

ISSN:0022-233X    

DOI:10.1080/00222338408056575

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Radical copolymerization of methyl vinyl ketone (MVK, M1) with acrylamide (AAm) and its derivatives, such as methacrylamide (MAAm) and N,N′ -dimethylacrylamide (DMAAm), was carried out in dioxane or ethanol using α,α - azobisisobutylonitrile as the initiator at 60°C under vacuum. The monomer reactivity ratios found in dioxane were as follows: ri = 1.06, r2= 6.41 for the MVK-AAm system; r1= 0.29, r2= 3.05 for the MVK-MAAm system; and r1= 0.95, r2= 0.26 for the MVK-DMAAm system. The n and r2values obtained in ethanol were as follows: r1= 0.88, r2= 1.18 for the MVK-AAm system; and r1= 0.37, r2= 2.04 for the MVK-MAAm system. Q2and e2values of AAm derivatives in dioxane were estimated to be 3.03 and 1.04 for MAAm and 2.15 and 1.11 for DMAAm, respectively. The Q2and e2values of MAAm in ethanol were estimated to be 2.67 and 1.21, respectively. Based on these results, the alternating copolymerizability depends on the interaction of monomer-monomer, and the strong solvent effect depends on the radical copolymerization of the AAm derivatives.

ISSN:0022-233X    

DOI:10.1080/00222338408056576

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Vinyl cinnamate (C) was synthesized and copolymerized with vinyl acetate (A) in benzene at 60° using benzoyl peroxide as initiator. Monomer distributions in the resulting copolymers were determined by the infrared spectral technique. A calibration curve was obtained for this purpose. Reactivity ratios as calculated by Kelen and Tüdös method were found to be rC= 1.401 ± 0.210, rA. = 0.043 ± 0.006.

ISSN:0022-233X    

DOI:10.1080/00222338408056577

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The polymerization of vinyl monomer with the bis (ethyl acetoacetato)copper(n) (Cu(eacac2) and the sodium tetraphenylborate (TPB) system was investigated. This binary system was found to initiate effectively the radical polymerization of methyl methacrylate (MMA) and methyl acrylate (MA). The polymerization of MMA with the Cu(eacac2)/TPB system was studied kinetically in acetone. The overall activation energy of the polymerization was calculated to be 15.8 kcal/mol. This value is a little lower than that (17.6 kcal/mol) for the polymerization of MMA with Cu(eacac)2alone. The polymerization rate (Rp) is represented byThe high order for the monomer concentration suggests participation of the monomer in the initiation process in this polymerization. This is supported by examination of the visible and ESR spectra of the Cu(eacac)2/TPB/MMA/acetone system. Reduction of Cu (II) to Cu(I) was observed from the ESR spectrum. To elucidate the initiation mechanism, the spin trapping technique was applied to the Cu(eacac)2)/TPB/MMA system. Based on these results, an initiation mechanism for the binary system of Cu (eacac)2and TPB is proposed and discussed.

ISSN:0022-233X    

DOI:10.1080/00222338408056578

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:0022-233X    

DOI:10.1080/00222338408056569

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor