摘要:

The paper describes an investigation of the preparation and properties of amylose phenylosazone and phenylhydrazone. Under the conditions used, amylose phenylosazone was not formed quantitatively and considerable degradation of the amylose occurred. The phenylhydrazone, however, can readily be prepared in quantitative yield and the polymer remains undergraded. Solutions of amylose phenylhydrazone in dimethylsulfoxide may be used to determine the number average molecular weight of amylose samples.

ISSN:0022-233X    

DOI:10.1080/00222337508068655

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The tentative identification of the reactive species in the condensation of Cp2TiCl2with salts of diacids to form titanium polysters is made. The reactive species are believed to be the same for both aqueous solution and interfacial systems, i.e., R -CO2−and Cp2Ti2+with reaction occurring in the aqueous phase. The condensation of Cp2TiCl2with disodium terephthalate in interfacial systems occurs via a pseudo-first-order reaction:

ISSN:0022-233X    

DOI:10.1080/00222337508068656

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The polymerization of vinyl monomers with a binary system composed of N-chlorosuccinimide (NCS) and some Lewis acids was investigated by means of kinetic and spectral determinations. It was found that the NCS-ZnCl2system was the most effective as an initiator of radical polymerization of methyl methacrylate, and this polymerization was initiated by a radical produced via the reaction of NCS and ZnCl2, and terminated bimolecularly. By applying a spin trapping technique to the reaction of NCS with ZnCl2, it was shown that the initiating radical was N-succinimidyl radical which was obtained through a homolysis at the N-Cl bond.

ISSN:0022-233X    

DOI:10.1080/00222337508068657

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The measurement of sorption and diffusion behavior of liquid ethanol and water solvent mixtures in polyurethane membrane were made simultaneously by thermogravimetry. The individual amounts of sorbed water and ethanol in the polymer membrane were estimated by thermogravimetry and differentiated by mass spectrometry. In addition, from a single dynamic thermogravimetric experiment the activation energy for solvent molecules desorbing from the polymer membrane was also determined. The thermodynamic activity of ethanol vapor in equilibrium with the ethanol-water-polyurethane system was determined by gas-liquid chromatography. The clustering functions, the mean numbers of solvent molecules in the clusters, and those associating with polymer sites were evaluated by applying simplified mathematical derivatives using the experimentally determined values of activity and volume fraction of solvent molecules. It was found that at lower ethanol concentration the tendency for ethanol molecules to cluster together is high. At higher ethanol activity, ethanol-polymer site interactions predominantly occurred.

ISSN:0022-233X    

DOI:10.1080/00222337508068658

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The rates of free radical copolymerizations at given rates of initiation can be analyzed ideally in terms of monomer feed concentrations and reactivity ratios, propagation rate constants for homopolymerizations of the particular monomers, and an overall rate constant for termination during copolymerization. This model, which is due to Atherton and North, can account for the effects of initiator concentration and viscosity of the polymerization medium on copolymerization rates.

ISSN:0022-233X    

DOI:10.1080/00222337508068659

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Radiation-induced polymerization of acrylonitrile-urea canal complexes formed in frozen ethylene glycol or tert-butyl alcohol media was investigated. Formation of canal complexes in the frozen state was prolonged. The initial rate of polymerization was enhanced in the frozen state. The degree of polymerization of polymers obtained is found to show no depression at high conversions and is higher in the frozen state, suggesting stabilization of canal complexes by the frozen medium.

ISSN:0022-233X    

DOI:10.1080/00222337508068660

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The radiation-induced polymerization of acrylonitrile in a frozen urea-ethylene glycol solution at −78° C was investigated. The thermal behavior of the system was also analyzed by using differential thermal analysis.

ISSN:0022-233X    

DOI:10.1080/00222337508068661

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The reaction between poly (4-vinylpyridine) and propargyl chloride was studied in methanol. It was shown that, independently of the ratio of reactants to each other, the end products of the reaction are polymers with conjugated bond systems formed by the opening of the propargyl triple bond which was activated by interaction with poly (4-vinylpyridine). It was shown that “normal” quarternization of poly (4-vinylpyridine) by propargyl chloride precedes accelerated polymerization of propargyl chloride which begins at 6 to 8% alkylation. It was established that the solution becomes structured before accelerated polymerization begins. A possible mechanism for this reaction has been proposed.

ISSN:0022-233X    

DOI:10.1080/00222337508068662

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The radiation-induced emulsion copolymerization of tetrafluoroethylene with propylene was carried out at room temperature in the presence of gaseous monomers. The formation of hydrofluoric acid in the course of polymerization was observed. The amount of HF formed increased linearly with the irradiation time at various dose rates in the early stage. The tendency was similar to that of time-polymer yield curves. The rate of HF formation was proportional to the first order of the dose rate. The amount of HF formed increased in the presence of oxygen and decreased remarkably above 1 wt% emulsifier, while the polymer yield decreased in the presence of oxygen and increased with the emulsifier concentration. A remarkable decrease in the amount of HF formed in higher emulsifier concentration is mainly attributable to chemical absorption or electrostatic capture of H+ion on polymer particles produced. Hydrofluoric acid is mainly formed by reaction between primary products (eaq−and H) from the radiolysis of water and organic fluoride (tetrafluoroethylene and emulsifier), and is little formed by reaction between primary products and copolymer produced. The G value of HF formation was in the order of emulsifier-water system > suspension polymerization > emulsion polymerization, while the polymer yield was in the order of emulsion polymerization > suspension polymerization.

ISSN:0022-233X    

DOI:10.1080/00222337508068663

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Styrene oxide (SO) and propylene oxide (PO) were copolymerized at temperatures between − 40 and +20° C using boron trifluoride etherate (BF3) as catalyst, 1,3-propanediol (DIOL) as cocatalyst, and ethylene dichloride (EC) as solvent. The initial rates of consumption of SO and PO varied as follows with the initial catalyst, cocatalyst, and comonomer concentrations:

ISSN:0022-233X    

DOI:10.1080/00222337508068664

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor