摘要:

The preparation and deesterification of a number of polymers and copolymers of unsaturated tetrahydropyranyl esters has been studied. The conditions required to remove the tetrahydropyranyl group from these esters are extremely mild. Hence it is possible to use dihydropyran as a protecting group in the preparation of polymers containing other groups susceptible to normal hydrolysis conditions. The reactivity ratios for the tetrahydropyranyl methacrylate/styrene and tetrahydropyranyl acrylate/styrene copolymerization systems have also been determined.

ISSN:0022-233X    

DOI:10.1080/00222337408066389

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Equilibrium isotherms of Na-H, K-H, Rb-H, Cs-H, and Ag-H systems for series of sulfonated polystyrene resins prepared from styrene and m- and p-DVB copolymers (2, 4, 8 mole % DVB) have been studied at 25[ddot] C. The difference between the selectivity coefficient (KHM) for the 8 mole % m-DVB resin and that for the para isomer resin is relatively large and increases with the natural order of affinity of the cations up to the silver ion. The isotherms of the commercial DVB resin are also different. The variation of KHMwith the cationic composition (XR) of the p-DVB resin is larger than that of the m-DVB resin as can be seen in the variation in the slope of plots. These facts are explained in terms of a variation in ion exchange sites which are related to the network structure of the copolymers. This indicates that the exchange sites are more uniformly distributed in the m-DVB resin that in the para isomer resin.

ISSN:0022-233X    

DOI:10.1080/00222337408066390

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The radiation protective effect of the breaking of secondary bonding in protein was examined with such amino acids as disodium inosine-5′ -monophosphate and disodium guanosine-5′ -monophosphate and vitamins such as thiamine and λ-ascorbic acid. The behavior of the viscosity change closely resembles that found with the sodium 1-glutamate as shown by a similar dependence on concentration.

ISSN:0022-233X    

DOI:10.1080/00222337408066391

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

When protein in various liquids containing aromatic hydrocarbons, such as benzene, naphthalene, and phenanthrene, is irradiated by γ-rays from a60Co source, the breaking of secondary bonding in the protein molecule varies with the irradiation liquids containing aromatic hydrocarbons. Protein irradiated by γ-rays from a60Co source in air showed the effect of pH on the breaking of secondary bonding in the protein molecule. In both cases an empirical equation for the viscosity change was obtained, and the phenomena were explained on the basis of the molecular mechanism.

ISSN:0022-233X    

DOI:10.1080/00222337408066392

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

A sample of clinic dextran (Mn= 54,000) has been fractionated by precipitation at 25° C in the system water/ethanol. Seven fractions were isolated in the usual way and freezedried. Fitting of the molecular weight distribution to the exponential functions of Tung and Schulz gives a good approximation, but it is improved by using a linear combination of the exponential, logarithmic, and normal functions, according to a method recently developed.

ISSN:0022-233X    

DOI:10.1080/00222337408066393

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Molecular weight distributions corresponding to three separate termination kinetics are derived using an approximation which is valid for large degrees of polymerization. The derivation is straightforward and suitable for introducing students to the significance of kinetics on molecular weight distributions.

ISSN:0022-233X    

DOI:10.1080/00222337408066394

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Earlier work indicated that in the radiation-induced grafting of vinyl monomers on polymeric films, the plasticity of the film being grafted is determined by the Hildebrand solubility parameter of the grafting solution. Film plasticity affects the termination step of the grafting reaction, and thus strongly influences the overall rate of monomer grafting on the polymeric film.

ISSN:0022-233X    

DOI:10.1080/00222337408066395

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The polymerization kinetics of C4, C8, and C12n-alkyl acrylates are characterized by monomer orders of 1.5 or greater and in the case of the C8and C12esters an initiator exponent of less than 0.5. Various explanations for the high monomer exponent have been considered including mechanisms based on intramolecular degradative transfer or the presence of a dimeric monomer species. Initiator exponents of less than 0.5 are explained in terms of a chain length dependence of the diffusion-controlled termination constant. Rotating sector curves have been obtained for the acrylates, and this data for n-butyl acrylate yields a value of 1.4×106dm3/ (mole)(sec) for the termination constant.

ISSN:0022-233X    

DOI:10.1080/00222337408066396

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Formulus and reaction conditions for the radiation-induced emulsion copolymerization of tetrafluoroethylene with propylene were studied at room temperature in order to obtain higher molecular weight copolymer than those obtained in bulk or solution. It was found that ammonium perfluorooctanoate as an emulsifier is most suitable to obtain a stable latex of high molecular weight copolymer with good reactivity. The high molecular weight copolymer is obtained by using the emulsifier at high mole fraction of tetrafluoroethylene under the saturated vapor pressure of the monomer mixture. The molecular weight range of copolymers obtained in this experiment was from 3.0×104to 8×104, and these are higher than those obtained in bulk or solution.

ISSN:0022-233X    

DOI:10.1080/00222337408066397

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Formulas and reaction conditions for the radiation-induced emulsion copolymerization of tetrafluoroethylene with propylene were studied at room temperature in the presence of gaseous monomers containing 50 mole % tetrafluoroethylene content. Stable latex was obtained by the use of ammonium perfluorooctanoate emulsifier. The resulting copolymer was a rubberlike material. A percentage of emulsifier greater than 1 wt% to water was suitable in this emulsion copolymerization. The conversion and the molecular weight were independent of the stirring speed above 400 rpm and decreased with a rise in temperature. An induction period was observed in the presence of oxygen. There was no effect of water purity on the emulsion copolymerization. When the stainless-steel reaction vessel was cleaned with a dilute acidic aqueous solution, the conversion was almost the same as that for a Pyrex reaction vessel.

ISSN:0022-233X    

DOI:10.1080/00222337408066398

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor