摘要:

The curing reaction of an unsaturated polyester (BAPM), prepared by polycondensation of Bisphenol A-di-(2-hydroxypropyl)ether and maleic anhydride, with vinyl monomers was investigated by IR and ESR. Thermal properties of the resulting polymer were studied by DSC and TMA. For the curing reaction of BAPM with styrene initiated with the cobalt naphthalate/1-hydroxycyclohexyl hydroperoxide system, the copolymerization process could be satisfactorily analyzed by the Mayo-Lewis integral equation for the usual homogeneous copolymerization. The reaction mixtures contained long-lived polymer radicals, the ESR spectra of which gave important information on the curing reaction. The DSC and TMA results showed that a microphase separation occurred in the cured polymer from BAPM and styrene. The phase separation was accelerated by treatment at -3°C. However, heat treatment above 150°C eliminated the phase separation. These phenomena were also confirmed by TEM examination.

ISSN:0022-233X    

DOI:10.1080/00222338808053362

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The copolymerization of 2-phenyl-4-methylene-1,3-dioxolane (PMDO) with acrylonitrile (AN) or with methyl methacrylate (MMA) gives rise to a copolymer spontaneously or in the presence of radical initiator. Higher yield of copolymers can be got in the presence of radical initiator. The structures of the obtained copolymers, confirmed by IR,1H-, and13C-NMR spectra, indicate that no ring-opening polymerization of PMDO takes place during copolymerization with AN or MMA. PMDO would not copolymerize with styrene (ST). During copolymerization, the formation of weak charge-transfer (CT) complexes with a mole ratio of unity for PMDO-AN and with more than unity for PMDO-MMA was demonstrated by NMR. The determination of their equilibrium constants (K) and ΔAcompwas attempted by using the Hanna-Ashbough equation with NMR spectroscopy. Based on the different ΔAcompvalues and chemical shifts of the accepter protons in the complex, the structural peculiarities of complexes are discussed. The contribution of the dative structure to the CT complex was assumed to affect the reactivity of CT complex monomer.

ISSN:0022-233X    

DOI:10.1080/00222338808053363

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The process of the Aa-crosslinking reaction is considered as a whole to approach the threshold of the sol-gel transition. By a rational way, without Stirling's approximation, the asymptopic form of the Flory-Stockmayer distribution near the gel point is obtained to reach a generalized scaling law.

ISSN:0022-233X    

DOI:10.1080/00222338808053364

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The course of the isothermal polymerization of methyl methacrylate in different concentrated solutions in toluene,n-butyl acetate, cyclohexanone, and dimethylformamide was measured at four temperatures by differential scanning calorimetry. The conversions at the sharp increase of the reaction rate were found to increase with dilution of the reaction mixture. The polymerization enthalpies and the composite rate constants were calculated. The polymerization enthalpies seem to be solvent independent. The composite rate constants for polymerization in butyl acetate are lower and those for polymerization in toluene are equal to the constants for bulk polymerization. They are independent of the concentration of the reaction system. The constants for polymerization in cyclohexanone and dimethylformamide are, however, concentration dependent. An interrelation between the composite rate constants and solubility parameters of the solvents and methyl methacrylate was found. The relative molecular weight averages decrease with decreasing concentration of the reaction mixture. The MW distributions were very broad.

ISSN:0022-233X    

DOI:10.1080/00222338808053365

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The effect of the addition of metal salts as catalysts for the acid interchange polycondensation of tetrachlorobisphenol A diacetate with phthalic acids was examined. The acetate salts of some transition metals were found to have an effect upon the molecular weights of the polyesters produced, but inherent viscosities above 0.50 dL/g were not achieved with these catalysts. Modification of the nature of the salts by either the use of a mixture of acetate and strong acid anionic species, or by addition of an equivalent of strong acid to the metal acetate, to generate a mixed saltin situ, gave the most effective catalyst for the polycondensation. Inherent viscosities as high as 0.82 dL/g were achieved with a catalyst system consisting of an equimolar mixture of nickel acetate and nickel perchlorate. As an approach to explaining the activity of the metal salt catalysis, it is proposed that a metal salt complex, consisting of a central divalent, tetracoordinate transition metal, surrounded by the oxygens from the phenyl acetates and from the incoming carboxylic acid, orients the reactants and facilitates transfer of acid functions.

ISSN:0022-233X    

DOI:10.1080/00222338808053366

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The polymerization kinetics of the divinyl monomerN,N′-methylenebisacrylamide (MBA) in aqueous acetic acid with the manganic acetateglycerol (GLY) redox system was investigated. The rate of polymerization,Rp, was proportional to [monomer]3/2[Mn(III)]0.5and [GLY]0.5. The rate of manganic ion disappearance,Rm, was directly proportional to [Mn(III)] and [GLY] but independent of monomer. Based on these results, a reaction mechanism which involves complex formation between Mn(OH)2+and GLY, cyclopolymerization of the growing radicals, and mutual termination was proposed. The rate of polymerization was compared with those for analogous monovinyl monomers.

ISSN:0022-233X    

DOI:10.1080/00222338808053367

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Cyclopolymerization kinetics of the nonconjugated divinyl monomerN,N′-methylenebisacrylamide (MBA) initiated by two different redox systems, trisacetatomanganese(III) dihydrate with either ethylene glycol or mercaptoethanol, in aqueous acetic acid at 35–50°C were investigated. Rates of polymerization and manganic ion disappearance were measured, and rate equations were derived from the observed dependence. Rate parameters were correlated with the differences in the reactivities of the radicals produced by the two systems toward the monomer and the metal ion. The rate of polymerization of MBA was compared with that of analogous monovinyl monomers.

ISSN:0022-233X    

DOI:10.1080/00222338808053368

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Polymerization of nonconjugated diolefins is of recent interest.N,N′-Methylenebisacrylamide (MBA), a nonconjugated diolefin, is generally used as a crosslinking agent. It can also be polymerized under certain conditions without crosslinking [1]. Butler and Ingley [2] proposed a novel chain propagation mechanism for such reactions in which the radical produced undergoes cyclization before the propagation step. Subbaratnam et al. reported the polymerization of MBA under thermal conditions [1, 3, 4]. Recently, polymerization of MBA with the vanadium(V)-cyclohexanone redox system was reported from our laboratory [5]. The present work on the photopolymerization of this monomer using uranylion as photosensitizer was undertaken with a view to find out whether cyclization of the radical occurs under these conditions or not, and also to establish the mechanism.

ISSN:0022-233X    

DOI:10.1080/00222338808053369

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Within the past 15 years, a considerable amount of our effort has been directed toward the syntheses and properties of the polymers containing phosphatidylethanolamine [1, 2] and choline [3–5] analogs in the side chains and phosphatidylcholine analogs in the main chains [6]. On the other hand, it is well known that biological membranes are formed of lipids and proteins composed of polypeptide chains [7]. Therefore, it seemed to be of great interest to prepare a synthetic polypeptide containing phospholipid analogs in the side chains.

ISSN:0022-233X    

DOI:10.1080/00222338808053370

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Vinyl polyesters combine the advantages of epoxy and unsaturated polyester resins [1, 2]. They are tough and adhere well to the substrate surface. With acrylic end groups, these resins turn photocrosslinkable [1]. However, photocurable vinyl polyesters are not as well reported as photocurable epoxy resins [3, 4] and unsaturated polyesters [5, 6]. Crosslinking with UV light is an excellent method for obtaining articles with thick cross sections, with or without reinforcement, without large heat build-up in the interior, which would damage the plastic [7]. We, therefore, thought of preparing a vinyl polyester resin from a photocurable diepoxide, such as the diglycidyl ether of 4,4′-dihydroxychalcone with acrylic end groups, and test its photofastness compared to that of the parent diepoxide. The results obtained are interesting, and the method of synthesis can be extended to a large number of photocrosslinkable vinyl polyesters.

ISSN:0022-233X    

DOI:10.1080/00222338808053371

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor