摘要:

AbstractDesign, calibration, and operation is described of a unique, 2‐liter laboratory‐scale continuous stirred tank reactor for the heterogeneous stereospecific polymerization of α‐olefins under pr

ISSN:0021-8995    

DOI:10.1002/app.1966.070100601

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

年代:1966

数据来源: WILEY

摘要:

AbstractCommercial thermoplastics may be classified by the types of rate curves obtained on thermal oxidation. The rate of oxidation of an acrylonitrile‐butadiene‐styrene plastic is affected by sample thickness and appears to be diffusion‐controlled. Pigmentation increases the reaction rate of this compound in all the cases studied because of the catalytic effect of the metals present. Carbon black adversely affects the oxidation rate of stabilized polypropylene. The acetal plastics decompose under oxidative condition at 140°C. Of the thermoplastics examined, polytetrafluoroethylene, fluorinated ethyleneproplyne copolymer, poly(vinylidene fluoride), poly(ethylene terephthalate), and polysulfone are the most resistant to thermal oxidation at

ISSN:0021-8995    

DOI:10.1002/app.1966.070100602

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

年代:1966

数据来源: WILEY

摘要:

AbstractA linear polymer with a high melting point is obtained from the water–formaldehyde–hydrogen sulfide system in the presence of sulfuric acid. This polymer is substantially formed by a polythiomethylene chain with a few oxymethylene units. Its formation involves a topochemical reaction of the mercaptomethanol present in solution on the first separation solid of the system. On heating, the polymer loses oxymethylene units; in the same way, the first solid product separated from the system loses formaldehyde and undergoes a morphological and chemical transformation to polythiomethyl

ISSN:0021-8995    

DOI:10.1002/app.1966.070100603

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

年代:1966

数据来源: WILEY

摘要:

AbstractThe monomolecular film behavior of polyvinyl acetate (PVAc), polyethyl acrylate (PEA) and mixtures of these ranging in concentration ratio of PEA to PVAc from 0.008 to 11.301 has been studied using a Langmuir‐type filmbalance over an aqueous 0.01NHCl substrate. Hysteresis was observed in the compression–expansion cycle for PVAc. A discussion of polymer–polymer interaction in a mixed monomolecular film at an interface is presented. The extent of this interaction for films comprising PVAc and PEA has been determined in terms of deviations of the film area from the ideal behavior. The data on the film areas of PVAc and PEA are discussed in terms of the molecular orientation of these polymers on the surface. A simple equilibrium thermodynamic treatment is applied to the data on mixed monolayer films. The implications resulting from this study are disc

ISSN:0021-8995    

DOI:10.1002/app.1966.070100604

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

年代:1966

数据来源: WILEY

摘要:

AbstractVolume changes during curing of an unfilled epoxy resin using a series of anhydrides were measured. It was shown that a significant reduction in shrinkage could be achieved by proper choice of structure.

ISSN:0021-8995    

DOI:10.1002/app.1966.070100605

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

年代:1966

数据来源: WILEY

摘要:

AbstractA study of the effect of three processing variables, melt temperature, quench temperature, and air pressure, on the gloss of polypropylene films shows that although these processing parameters are used to control this property they do not constitute the primary cause of gloss variations. The main causes of gloss variations were found to be changes in the polymer melt index, i.e., melt roughness, and film crystallinity, both of which can be controlled by changing the processing conditions.

ISSN:0021-8995    

DOI:10.1002/app.1966.070100606

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

年代:1966

数据来源: WILEY

摘要:

AbstractData are presented showing that rapidly quenched polypropylene films contain a paracrystalline phase in addition to crystalline and amorphous phases. The density of the paracrystalline phase was found to vary between 0.8890 and 0.9080 g./cm.3. Other data show that the density of quenched polypropylene films increases during aging, the increase being a linear function of the logarithm of the film age. The physical properties of the films, secant modulus, impact strength, and coefficient of friction, were found to vary not only with crystallinity, i.e., composition‐dependent density, but also to vary during aging when the density was increasing with little change in crystallinity. An example of this dependence is the increase in secant modulus of 10.9 × 106psi/g./cm.3during aging and only 3.7 × 106psi/g./cm.3as the crystallinity increased. Because of the three phases and the density–time change, it is possible to have films with the same density and different physical properties and, conversely, films with the same physical properties and different dens

ISSN:0021-8995    

DOI:10.1002/app.1966.070100607

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

年代:1966

数据来源: WILEY

摘要:

AbstractGel permeation chromatography produces a type of differential molecular weight distribution directly and rapidly. Conversion of these data to conventional molecular weight distributions and plots of distributions is time‐consuming. A computer program is described to perform these operations readily. Input data from the automated chromatograph, elution volume, and recorder deflection are converted to unit sensitivity and base line corrections applied. The curve is then numerically integrated and a calibration curve used to convert elution volumes into molecular weights. Various calibration curves can readily be introduced into the program. The output, in addition to tabulation of cumulative and differential molecular weight distributions, contains values ofM̄n,M̄v,M̄w,M̄z, andM̄z+1. Importantly, a reduced absolute area, i. e., area computed for unit sensitivity on a unit concentration basis, is tabulated. An additional time‐saving eature is the printing out of differential and cumulative molecular weight distribution curves and of a differential h

ISSN:0021-8995    

DOI:10.1002/app.1966.070100608

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

年代:1966

数据来源: WILEY

摘要:

AbstractViscosity parameters were obtained for maize maylose (molecular weight of 107,000) in 1NKOH at 25, 30, 35, and 40°C. Intrinsic viscosity continuously decreased and Huggins' constantk' continuously increased with increasing temperature. The temperature dependence of intrinsic viscosity,d[η]/dT, was −2.12 × 10

ISSN:0021-8995    

DOI:10.1002/app.1966.070100609

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

年代:1966

数据来源: WILEY

摘要:

AbstractThe starch–polyacrylonitrile graft copolymer prepared from gelatinized wheat starch with ceric ammoninm nitrate as the initiator has been freed of ungrafted polyacrylonitrile and separated into fractions by extraction with dimethylformamide, γ‐butyrolactone, and dimethyl sulfoxide. The copolymer fractions obtained differed appreciably in level of add‐on, molecular weights of grafted chains, and grafting frequency. To determiue the molecular weights of grafted chains, the starch part of the copolymer was effectively removed by hydrolysis with α‐amylase. It was necessary to dissolve or swell the polymer in dimethyl sulfoxide and freshly precipitate it by addition to water before enzymatic hydrolysis. In studying the effect of reaction medium on copolymer composition, there was less ungrafted homopolymer formed and a higher yield of graft copolymer possessing more frequent grafts with water than with aqueous dimethylformamide or aqueous ethylene glycol. Polymer solubility, the results of control polymerizations of acrylonitrile in the absence of starch, and the detection of glucose endgroups on the polyacrylonitrile liberated from the fractionated polymer by hydrolysis are presented as evidence that the copolymers obtained are true grafts rather thau intimate

ISSN:0021-8995    

DOI:10.1002/app.1966.070100610

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

年代:1966

数据来源: WILEY