摘要:

2(2-Hydroxy-5-isopropenyl)2H-benzotriazole and 2(2-hydroxy-5-vinylphenyl)2H-benzotriazole, both of which are well-established polymerizable ultraviolet stabilizers, have been co- and terpolymerized with N-vinylpyrrolidone, 1,1,1-tris(trimethylsiloxy)-methacrylato-propylsilane, and various methacrylate esters. Additionally, 4-isopropenyl-2,6-ditertiarybutyl phenol was co-and terpolymerized with these monomers as such to provide polymer compositions stable against autoxidation or in combination with the 2(2-hydroxy-5-isopropenylphenyl)2H-benzotriazole to provide stability against autoxidation and photooxidation. The polymerizations resulted in insoluble polymers from which the ultraviolet stabilizer or the antioxidant could not be extracted or leached out. The stabilized polymers had water absorption behavious similar to that co- and terpolymers without the incorporation of the polymerizable stabilizers.

ISSN:0022-233X    

DOI:10.1080/00222338608063406

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Free radicals produced in styrene and maleic anhydride mixtures and in solutions in acetone and chloroform by UV photolysis at 90 K have been studied by electron spin resonance and changes observed on warming. A doublet spectrum observed in all systems containing maleic anhydride has been assigned to the radical formed by H addition to a carbonyl group in the monomer, and not to the corresponding radical on maleic anhydride units in the copolymer or to the maleic anhydride propagating radical. Interpretations of copolymerization mechanisms based on radicals produced in frozen comonomers in bulk or in solution by photolysis or radiolysis must therefore be viewed with caution.

ISSN:0022-233X    

DOI:10.1080/00222338608063407

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A series of water-soluble starch-polyacrylamide graft copolymers (ST-g-PAM) were prepared by Ce4+-initiated graft copolym-erizations of acrylamide (AM) onto starch (ST) dissolved in water at 30°C. The copolymers were found to contain 3-33% (wt) of ST. The structure of the copolymers, including the average number of grafts per chain and the efficiency of the initiator, was determined by acid-catalyzed degradation of the ST followed by size exclusion chromatography (SEC) analysis of the PAM chains and was found to be consistent with the presence or absence of free ST in the polymerization product prior to hydrolysis. The average number of grafts per starch molecule was found to be three or less, depending on conditions. The initiator efficiency (6–43%) was shown to decrease with increasing [Ce4+] and decreasing [AM], and this was found to be qualitatively in accord with the proposed mechanism of initiation and polymerization. The low efficiency was shown to be due, in part, to the low rate of reaction of Ce4+compared to the polymerization rate. The copolymers were characterized by ultra-centrifugation, SEC, and viscometry.

ISSN:0022-233X    

DOI:10.1080/00222338608063408

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Membrane filtration and equilibrium dialysis using Nucleopore membranes have been carried out to determine the hydrodynamic sizes of large water-soluble polymers. The macromolecules were found to have been significantly deformed even under very low stress. Multicell equilibrium was somewhat long. The hydro-dynamic radius obtained from this method was found to be in reasonable agreement with that found by ultracentrifugation and size exclusion chromatography.

ISSN:0022-233X    

DOI:10.1080/00222338608063409

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The ultrasonic degradation of hydroxyethylcellulose (HEC) and poly (ethylene oxide) (PEO) in aqueous solution, and the copolymerization of HEC with PEO were studied. The structure of the copolymer was identified by DTA, IR, MS, x-ray diffraction, and polarizing microscopy. The copolymer prepared is mainly block. The copolymer formed amounts to 55.07% by irradiating 0.5% HEC/PEO aqueous solution for a period of 10 min at 25°C and 18.2 kHz with 2.5 A input current on a reversed main circuit.

ISSN:0022-233X    

DOI:10.1080/00222338608063410

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Isomerization of the adduct resulting from the protonation of 5-methylene-2-norbornene by trifluoroacetic acid was studied byUC-NMR spectroscopy. Relative rate constants were determined under various experimental conditions. The influence of temperature, solvent, and relative reactant concentrations was examined.

ISSN:0022-233X    

DOI:10.1080/00222338608063411

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

3,3-Dimethoxycyclopropene, the first of a series of cyclopropenone ketals, was initially reported from these laboratories in 1972. Polymerization of this compound, which is functionally capable of undergoing polymerization via both vinyl addition and ring opening, has not been previously studied. It was the purpose of this investigation to study this monomer as well as some of its homologs and to report their polymerization characteristics. An improved method of monomer synthesis is also reported. Among a variety of conventional cationic initiators investigated, only boron fluoride etherate was effective as a polymerization initiator. The mechanism proposed involves ring opening of the cyclopropene moiety to generate a dialkoxy-carbocation intermediate, followed by propagation via several distinct and simultaneous pathways to produce a complicated polymer structure. Elucidation of the structure was aided by the synthesis of several appropriate model compounds. The reluctance of these monomers to lend themselves to normal modes of propagation is attributed to the formation of an exceptionally stable carbocation intermediate which is relatively ineffective in further ring opening of the monomer. Isolation and characterization of these intermediates was achieved, and their low reactivity toward monomer was demonstrated. The cyclopropenone ketals studied were not converted to polymers via radical initiation.

ISSN:0022-233X    

DOI:10.1080/00222338608063412

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Cyclopropenone ketals are functionally capable of undergoing both vinyl and ring-opening polymerization. In a previous paper we reported ring-opening polymerization via boron trifluoride etherate initiation to yield a polymer of complicated structure. However, this previous study showed that conventional cationic initiators yield an exceptionally stable carbocation intermediate which is essentially incapable of further propagation. This paper reports the effective use of the unconventional cationic initiator, elemental bromine, to yield polymer, proposed to be formed by a sequence of steps which involve initial addition of bromine to the cyclopropene double bond, followed by electrophilic ring opening of the brominated cyclopropane ring and propagation via the carbocation intermediate formed. At least three different and simultaneous pathways are believed to be involved. The resulting polymers have [Mbar]nvalues in the range of 10,000.

ISSN:0022-233X    

DOI:10.1080/00222338608063413

出版商:Taylor & Francis Group    

年代:1986

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:10.1080/00222338608063405

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor