摘要:

AbstractThen‐alkyl α‐cyanoacrylates from methyl throughn‐octyl exhibit a reverse order of polymerization rate on biological substrates compared to that on water. On water, the lower homologs spread and polymerize rapidly, whereas the higher homologs spread but polymerize slowly. On biological substrates, the lower homologs do not spread or spread slightly and the higher homologs exhibit large spreadabilities and very rapid polymerization rates. Determination of the spreading coefficients for these systems by using the monomers or model compounds confirm the observed spreadabilities. It is proposed that the increased rate of polymerization of the higher homologs on biological substrates may be due to increased catalyst concentrations on these surfaces or to the solubilization of the higher homologs at the interface, making the catalyst sites more available to the monomer. The suggestion is made that if the liquid monomers spread and orient on the substrate and subsequently polymerize, the polymers will maintain the orientation. If such is the case, a technique is available for preparing stereospecific vinyl polymers which may have different spatial configurations depending on the polarity of the liquid substrate upon which they have been allowed to spread and poly

ISSN:0021-8995    

DOI:10.1002/app.1966.070101101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY

摘要:

AbstractA technique has been developed which provides a means for estimating polypropylene fractionation conditions in an elution column from a knowledge of the fractionation conditions used to fractionate linear polyethylene in the column and the solution behavior of both polymers in the same solvent‐nonsolvent system of varying compositions. The fusion behavior of linear polyethylene and isotactic polypropylene in mixtures ofo‐di‐chlorobenzene and dimethyl phthalate of varying compositions has been studied by a differential thermal analysis (DTA) technique using concentrations similar to those in an elution fractionation column. The column temperature for fractionating each of these polymers by usingo‐dichlorobenzene and dimethyl phthalate as the solvent and nonsolvent, respectively, was determined from their melting temperatures in dimethyl phthalate. On the basis of the equivalence of the fractional depression in solution temperature of each polymer in the binary liquid mixture, the composition range of solvent‐nonsolvent mixtures to be used in fractionating polypropylene was estimated from a knowledge of the polyethylene fractionation conditions together with the DTA data. Although separation depends primarily on molecular weight, the equivalence in fractional solution temperature depression provides a convenient means of correlating fractionation conditions for the polyolefins inv

ISSN:0021-8995    

DOI:10.1002/app.1966.070101102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY

摘要:

AbstractVery different concentration dependences of the viscosity of polymer solutions are predicted by the free volume treatments of Fujita and Kishimoto and of Kelly and Bueche. This latter is conveniently extended, and it is shown that it can describe a given set of experimental data over a concentration range much larger than the Fujita‐Kishimoto equation

ISSN:0021-8995    

DOI:10.1002/app.1966.070101103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY

摘要:

AbstractThe breaking times of two crosslinked epoxy polymers under constant stresses were found to decrease at high temperature and humidity. The effect of humidity is, in terms of Bueche's theory, to increase the jump frequency of the polymer segments and to reduce the number of polymer units in cooperative motion in a jump process. When two epoxy polymers with different segment mobilities are compared at a given temperature, the stress‐breaking time relationship shifts toward longer times for the polymer with the higher transition temperature. The relation is also applicable in the presence of absorbed water molecule

ISSN:0021-8995    

DOI:10.1002/app.1966.070101104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY

摘要:

AbstractAn analysis of the dependence of the breaking timetbof a glassy polymer under constant stress on the molecular weight of the polymer is made with the use of the theories by Bueche and by Cohen and Turnbull. It is concluded that logtbis proportional to the degree of polymerizationxwhenxis small but becomes independent ofxat large values ofx.

ISSN:0021-8995    

DOI:10.1002/app.1966.070101105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY

摘要:

AbstractSolubility and spectroscopic evidence are presented to support the formation of A‐B block copolymers between monomers undergoing anionic polymerization (A units) and monomeric formaldehyde (B units). Comonomers included in the study were styrene, methyl andn‐butyl methacrylate, acrylonitrile, isoprene, andN,N‐di‐n‐butylacrylamide. Similar evidence is presented on the formation of B‐A‐B copolymers between styrene and α‐methylstyrene and formaldehyde; an A‐(B‐C) random copolymer of styrene, formaldehyde, and phenyl isocyanate (C) was also prepared. Experimental details for the preparation of high‐purity, monomeric formaldehyde suitable for such work is described in some detail. It should be emphasized that this study was directed primarily toward showing the feasibility of preparing formaldehyde block copolymers; therefore, further work is needed to establish the quantitative nat

ISSN:0021-8995    

DOI:10.1002/app.1966.070101106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY

摘要:

AbstractThermal diffusivity, thermal conductivity, and specific heat per unit volume were measured for the following polymers: poly(ethylene terephthalate), polytetrafluoroethylene, polycarbonate, polypropylene, and three poly(vinyl chloride) samples plasticized to different levels. First‐ and second‐order transitions can be identified and located by the following features in the thermal property‐temperature curves: discontinuities, sharp inflections, broad inflections, sharp maxima, broad maxima, and change in linear slope. The results for poly(vinyl chloride) indicate the possibility of the use of plasticizer to control the thermal insulation properties of polymers, both for steady‐state and unsteady‐state c

ISSN:0021-8995    

DOI:10.1002/app.1966.070101107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY

摘要:

AbstractMembranes prepared from 5% Parlodion solution have been characterized. These and other membranes prepared from 0.38, 0.5, 1.0, 2.0, and 3.0% Parlodion solutions and already characterized, have been used severally to estimate the number of anionic sites present in them by two different methods. The potentiometric method, which is indirect, gave values ofX̄Pwhich were higher thanX̄T, the values obtained by a direct isotopic method. The order was reversed for well‐characterized ion‐exchange membranes. These discrepancies were attributed to the shortcomings of the Teorell, Meyer, and Sievers theory of membrane potentials from which the potentiometric method was de

ISSN:0021-8995    

DOI:10.1002/app.1966.070101108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY

摘要:

AbstractThe oxidative stability of rubbers depends on the structure of the rubber and the impurities contaminating the rubber. It is known that the oxidation of natural rubber is accelerated by the presence of metallic impurities. Besides GR‐S rubber and nitrile rubber, the effects of metallic impurities on the oxidation of new rubbers, especially those introduced after the discovery of Ziegler‐Natta catalyst, have not been reported. In the first part of this paper, the theoretical background on the mechanisms of metalcatalyzed oxidation is given. Most of the early work was carried out for the oxidation of hydrocarbons in the liquid phase. The difficulties in applying the liquid‐phase results to the oxidation of high polymers in the solid phase are mentioned. The new rubbers used for this study are polyisoprene, polybutadiene,cis‐poly‐1,3‐butadiene, styrenebutadiene copolymer, butyl rubber, ethylene‐propylene terpolymer (EPT), propylene oxide rubber, polyacrylic rubber, and butadiene‐acrylonitrile rubber. The effects of stearic acid and various stearates on the oxidation of these rubbers are presented. The number of electrons transferred by the metal ion during redox reactions was found to be related to the effectiveness of the ion as a catalyst. Both the high and low oxidation states of the metal ion were shown to be active catalysts, supporting the accepted theory of metal catalysis through a hydroperoxide decompos

ISSN:0021-8995    

DOI:10.1002/app.1966.070101109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY

摘要:

AbstractThe metal‐catalyzed oxidation of polybutadiene is further discussed. The mild catalytic effect of stearic acid on the oxidation was shown due to the synergism of the acid and a stearate. The synergism was also found for the mixture of two different stearates. The results of the preliminary study on the stabilization are given. For both iron and copper stearates, zinc diethyldithiocarbamate (ZDC) was found to be the best metal deactivator, and the chelated mixture behaved as an oxidation inhibitor. Tetramethylthiuram disulfide (TMT), phenyl‐β‐naphthylamine, and oxamide were less eff

ISSN:0021-8995    

DOI:10.1002/app.1966.070101110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1966

数据来源: WILEY