摘要:

Homo- and copolymerizations of β-allyloxypropionaldehyde (I) have been carried out by photoirradiation at 12–13°C in degassed glass ampules. The number-average molecular weights of the homopolymers of I obtained in a few reaction conditions were determined by means of gel-permeation chromatography. I initiated and/or accelerated the photopolymerizations of such vinyl monomers as methyl methacrylate and vinyl acetate. Photocopolymerizabilities of I with styrene (St) and acrylonitrile (AN) were also investigated, and the copolymerization parameters were obtained as follows: for the St-I system, r1= 12, r2= 0.01; for the AN-I system, r1= 5.2, r2= 0.01.

ISSN:0022-233X    

DOI:10.1080/00222338008068112

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The effect of chain-binding on the reactivity of naphthyl groups towards intermolecular exciplex formation with triethylamine has been investigated. Polyamides of 2,6-bis(N-methyl methyl-amino)naphthalene with the diacid chlorides ClOC(CH2)xCOCl (x = 2, 4, 6, and 8), designated P-2, P-4, P-6 and P-8, and 2,5-bis(n-methyl N-acetyl methylamino)naphthalene (MC) have been studied. Fluorescence spectra of dilute solutions of the poly-amides and their model compound have been obtained in the presence of varying amounts of triethylamine (TEA) as a quencher. The variations of exciplex monomer fluorescence intensity ratio, IE/IM, with quencher concentration indicates the following reactivity order: MC > P-8 > P-6 ± P-4 > P-2, which reflects the relative diffusion rate and accessibility of the naphthalene moiety. This order also represents the relative chain flexibilities of the polyamides studied. Monomer fluorescence quenching is explained in terms of a scheme involving formation of an exciplex, and a nonfluorescent CT encounter complex. Stern-Volmer plots of monomer fluorescence quenching reveal an anomalous order where the monomer fluorescence of the model compound is less effectively quenched. This may imply a slower dissociation rate constant of the nonfluorescent encounter complex in the case of the polymers.

ISSN:0022-233X    

DOI:10.1080/00222338008068113

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The formation of the water-soluble glycolchitosan-copper (II) complex was studied by ultraviolet and visible spectroscopy and by viscosity measurement. The structure of the polymer complex in question was found to change with pH value of the system. The glycolchitosan-copper (II) complex was active as a free-radical initiator for the polymerization of methyl methacrylate and acrylonitrile in the presence of carbon tetra- chloride. The maximum conversion was observed at neutral pH, and was influenced by the presence of neutral salts. Relation- ship between the activity of the polymer complex for initiating the polymerization and its structure was discussed.

ISSN:0022-233X    

DOI:10.1080/00222338008068114

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The polymerization of styrene initiated by 2,2′-azobisisobutyro-nitrile (AIBN) had been studied in N, N-dimethylformamide (DMF) at 60°C in presence of tris azido-iron(III) complex. The complex was prepared in situ by mixing solid sodium azide with hexakis(N, N-dimethylformamide)iron(m) perchlorate, [Fe(DMF)6] (ClO4)3, in the ratio 3:1. The nature of the complex formed was established by Job's method. The equilibrium constant for Fe3++ 3N3−Fe(N3)3determined by the limiting logarithmic method is 6.14 ± 106liter3/mole3. The velocity constant for the polystyryl radical towards the complex is 3.13 ± 104liter/mole-sec.

ISSN:0022-233X    

DOI:10.1080/00222338008068115

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

2-(Mercaptobenzothiazolyl)ethyl vinyl ether (TVE), 2-mercaptobenzoxazolyl)ethyl vinyl ether (OVE), and 2-(mercaptobenzimidazolyl)ethyl vinyl ether (IVE) were prepared from the reactions of the respective mercaptobenzazoles with chloroethyl vinyl ether. These monomers homopolymerized with cationic initiator to give relatively low molecular weight resinous materials, but radical initiator gave no polymer. The radical copolymerizations with vinyl chloride (VC) as M1were performed, and the colorless copolymers were obtained when the VC contents were more than ca. 50 mole %. The monomer reactivity ratios and Q, e values were determined as follows: TVE (M2)-VC: r1= 2.02, r2= 0.164, Q2= 0.02, e2= -1.85, OVE(M2)-VC: r1= 1.65, r2= 0.134, Q2= 0.02, e2= -2.03, IVE(M2)-VC: r1= 0.05, r2= 14.0, Q2= 0.04, e2= -0.20. These copolymers were less thermally stable than, the ordinary PVC. These monomers could easily undergo alternating copolymerization with maleic anhydride.

ISSN:0022-233X    

DOI:10.1080/00222338008068116

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The radical copolymerization of N, N-dimethylacrylamide (I) with styrene (St) (M1) was carried out in several solvents at 60 and 80°C. The monomer reactivity ratios were considerably affected by the reaction conditions. Linear correlationships were observed by plots of the values of both νC=0and νC=Cstretching frequencies of I obtained in the solvents against those of log r1, log r2, ΔΔE‡ (= ΔE11‡ - ΔE12‡), and ΔΔS‡ (= ΔS11‡ - ΔS12‡). The values of both ΔE12‡ and ΔS12‡ were also determined.

ISSN:0022-233X    

DOI:10.1080/00222338008068117

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Aspects of the radiation-induced polymerization of methacrylic acid in the crystalline state have been investigated and utilized to evaluate the mechanism of polymerization. In particular, results for post-irradiation polymerization at 0°C after radiation doses of 0.1 to 2.0 Mrad support the concepts of Lando and Semen that chain initiation essentially all commences at the same time, that chain propagation continues without termination, and that termination of nonpropagating radicals proceeds simultaneously.

ISSN:0022-233X    

DOI:10.1080/00222338008068118

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The kinetics and the mechanism of retarding action of cinnamic acid on the Ce(IV)-initiated polymerization of acrylonitrile were studied in the temperature range 35–45°C. The rate of polymerization Rpwas measured with respect to its dependence on time, monomer, metal ion, cinnamic acid, perchloric acid, acetic acid, sodium perchlorate, sodium sulfate, and manganese sulfate. The most significant observation was the rate mechanism. The process of polymerization was initiated by Ce(IV) alone and terminated essentially by the free radical produced by the interaction of Ce(IV) with cinnamic acid, which seems to be a general observation for all retarding substrates.

ISSN:0022-233X    

DOI:10.1080/00222338008068119

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The aqueous polymerization of acrylamide initiated by the acidified potassium permanganate/mercaptosuccinic acid redox system was studied at 35 ± 0.2°C in nitrogen. In the studied range of activator concentration (2.0 × 10−3to 6.25 ± 10−3mole/liter) the polymerization rate remains unaffected. The initial rate of polymerization varies linearly with KMnO4and acrylamide concentrations in the studied range. The activation energy was found to be 6.61 kcal/mole (27.63 kJ/mole) in the temperature range of 30–50°C. The molecular weight of polyacrylamide was found to be independent of [KMnO4] but increased with increasing monomer concentration. The effect of DMF on polymerization rate and molecular weight was also investigated.

ISSN:0022-233X    

DOI:10.1080/00222338008068120

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Thermal decomposition and glass transition temperature studies have been carried out on poly-p-isopropylstyrene (PpiPrS) with a differential scanning calorimeter. The un-decomposed polymer as well as its decomposition products were analyzed by gel permeation chromatography (GPC), infrared spectroscopy (IR) and nuclear magnetic resonance (NMR). During isothermal treatments in the 25–150°C temperature range (α < 3%), the observed increase in M arose primarily from interchain linking between the longer radical-bearing chains. Beyond 315°C (α > 6%), the molecular weight increases result from crosslinking reactions between decomposed polymer and longer undecomposed chains. During interchain linking, the number of isomethyl groups (iso-CH3) increase. In the crosslinking reactions that take place at temperatures beyond 315°C, the number of iso-CH3and terminal or α-methyl groups (α-CH3) both increase while the number of methylene groups (CH2) decreases. Activation energies of decomposition for various homologs of polystyrene (PS) obey the following order: EPS> EPpiPrS> EPpiPrαMeS≥ EPαMeS. A comparison of the Tgevalues of PS with those of PpiPrS, poly-α-methylstyrene (PαMeS) and poly-p-isopropyl-α- methylstyrene (PpiPrαMeS) shows that the presence of the p-isopropyl groups lowers the Tgof PS as well as that of PaMeS by about 30–35° K.

ISSN:0022-233X    

DOI:10.1080/00222338008068121

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor