摘要:

AbstractIn order to prepare the functional and fine powdery polymer, glycidyl methacrylate (GMA) and divinylbenzene (DVB) were polymerized in cyclohexane. This polymerization was heterogeneous. In the time–conversion curve, an autoaccelerating phenomenon and an apparently steady state were observed, and the activation energies for both reactions in the earlier stage and the steady state were calculated to be 28 kcal/mole and 11 kcal/mole, respectively. It is especially noteworthy that the increase in the DVB concentration decreased the polymerization rate. The diffusion of the monomers through the polymer matrix should be one of the most important factors. Some properties of the copolymer and its application as a mordant were studie

ISSN:0021-8995    

DOI:10.1002/app.1973.070171001

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

年代:1973

数据来源: WILEY

摘要:

AbstractPolybutadiene grafted to silica (PG) was prepared by the reaction of living polybutadiene with chlorinated silica. The graft efficiency was below 10%. PG and PG–commercial butadiene rubber blend were cured with sulfur. In either vulcanizate, the following phenomena were found as compared with the controlled samples: tensile modulus increased, degree of swelling and elongation lowered, and tensile strength unchanged. These results showed nearly the same tendency as had been found in the case of the rubber compounded with silica which was treated by coupling agents. In spite of a high tensile modulus of PG vulcanizate, it resulted in a lowering of the dynamic modulus compared with the controlled sampl

ISSN:0021-8995    

DOI:10.1002/app.1973.070171002

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe viscous and elastic properties of bromine‐terminated polybutadiene were investigated as functions of temperature, molecular weight, and molecular weight distribution. They were found to depend on these variables in a manner similar to other polybutadienes. It was shown that the effect on the viscous properties due to bromine terminal functionality is not as great as for carboxyl and/or hydroxyl terminal functionality. In this study it was shown that the viscosity resultant from the blending of two samples of the same polymer differing in molecular weight is dependent on the polydispersity of the polymers from which the blend is prepared. A form of the Ninomiya and Ferry theory was modified and compared with experiment. As a result of the experiments involving blending, it was shown that the temperature dependency of elasticity is less for polymers exhibiting greater polydispersit

ISSN:0021-8995    

DOI:10.1002/app.1973.070171003

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

年代:1973

数据来源: WILEY

摘要:

AbstractIn order to evolve the methods of mechanical spectroscopy and find new methods of studying the rise of nonlinear viscoelasticity, periodic square and triangular stress functions have been used. A “new” viscoelastic function is defined, logJ2=g{logJ1}, whereJ1andJ2are the compliances at the time (ζ/2 + 2nζ)n→∞for an odd, periodic, square function and an even, periodic, triangular function, respectively, with periods of 2ζ. The function shows characteristic shapes for viscoelastic spring and dashpot models. The interrelations between the complex compliance andJ1andJ2are developed; and since the sum ofJ1andJ2at the time ζ/2 agrees very well with the creep compliance at the same time,J1andJ2can be used as an interrelation between complex compliance and creep compliance. Special equipment for measuring the compliancesJ1ndJ2i

ISSN:0021-8995    

DOI:10.1002/app.1973.070171004

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

年代:1973

数据来源: WILEY

摘要:

AbstractIn an earlier paper, a “new” viscoelastic function, logJ2=g{logJ1}, was defined. For polymers, the linear viscoelastic behavior of which is characterized by “simple segment movements” in their main transition regions, the following general properties are found: (1) The local maxima of the function for different polymers fall along a straight line width the slope approximately equal to 1.1. (2) A characteristical general shape is noticed for the function after shifting along the straight line and reducing theJ1compliance as regards the “frozen in” complianceJ10. (3)J1reflects the storage andJ2, the loss mechanisms of the system. The relationJ2/J1is an expression for the average retar

ISSN:0021-8995    

DOI:10.1002/app.1973.070171005

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

年代:1973

数据来源: WILEY

摘要:

AbstractBased on the general properties of the function logJ2=gα{logJ1}, discussed in earlier papers,1,2the existence of two superimposed dispersion mechanisms in the glass–rubber transition of polyisobutylene (PIB), and poly(vinyl acetate) (PVAc) is discussed. A simple weighting model is used for separation of the two mechanisms. For the interpretation of the β‐mechanism, in PIB, the following facts are taken into account: (a) The loss maximum of the β‐mechanism appears in a zone where only very reduced segment movements occur. (b) The methyl side groups in PIB require special conformations of the main chains before they can rotate. (c) The apparent activation energy for the β‐mechanism is approx. 20 kcal/mole. Thus, for PIB the following interpretations for the α‐ and β‐mechanisms are proposed: (1) The α‐mechanism is due to simple segment movements. (2) The β‐mechanism appearing in the “Tgregion” is due to coupled movements between the main chain and methyl side groups. The ester groups of poly(vinyl acetate) need a lot more space for their rotations than the carboxy groups of poly(methyl acrylate) and can be expected to give considerable steric hindrance. It is therefore reasonable to suppose that a transition mechanism similar to the β‐mechanism of polymethacrylates will appear in the “freezing” region of poly(vinyl acetate). The analysis of the β‐mechanism is made using the same sep

ISSN:0021-8995    

DOI:10.1002/app.1973.070171006

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe existence of superimposed transition mechanisms in the “Tgregion” of polymethacrylates has been indicated by several authors including Ferry and co‐workers, who also have tried to separate the mechanisms. Using the general properties of the viscoelastic function logJ2=gα{logJ1} and a simple weighting model, the α‐and β‐mechanisms have been separated. The viscoelastic function logJ2=gβ{logJ1} is determined and is found to coincide both where different polymethacrylates are concerned and for the calculated as well as the directly

ISSN:0021-8995    

DOI:10.1002/app.1973.070171007

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe polydispersity index,Mw/Mn, of the product of an ideal continuous stirred tank reactor can be predicted from batch reactor data. A method for the prediction, in the case of high‐density polyethylene synthesis, comes from finding the effect of catalyst age upon yield,Mw, andMnin a batch reactor operated at constant pressure. These catalyst age effects are combined with the catalyst age distribution in the continuous reactor, and integration over all ages gives the yield and the polydispersity index for the continuous reactor product. This scheme for prediction was applied to a particular catalyst system, and the calculated values have been found to agree with observation

ISSN:0021-8995    

DOI:10.1002/app.1973.070171008

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

年代:1973

数据来源: WILEY

摘要:

AbstractIn flex testing of elastomers, the length of a cut is measured periodically as a function of the number of flexing cycles. In most cases a large number of measurements is accumulated for each test piece which would lead one to believe that the results should have a high degree of precision. This, however, is not the case, mainly because not all of the measurements are used to express the final result. Instead of being a precise test, flex testing is in fact notorious for its irreproducibility. A new method is proposed for computer treatment of flex data in whichallof the flex measurements are fitted to an empirical equation by means of nonlinear regression analysis. From the fitted equation, more precise estimates of rate of growth and growth initiation point can be obtained than is possible using the data treatment procedures proposed by ASTM. Also a new index of flex life is defined which is conveniently scaled from 0–100. This so‐called flex index is a convenient index of overall flex behav

ISSN:0021-8995    

DOI:10.1002/app.1973.070171009

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

年代:1973

数据来源: WILEY

摘要:

AbstractMolecular weight distributions and molecular aggregation for poly(vinyl chloride) (PVC) polymerized in bulk at −10, −30, and −50°C have been measured using gel permeation chromatography. The aggregate content in PVC polymerized at −50°C was found to be 87 wt‐%. These spherical aggregates of mean diameter of 5000 A are formed preferentially from PVC chains having high molecular weights and long syndiotactic sequence lengths. A temperature of 200°C was used to disintegrate these aggregates into single PVC molecules. In disagreement with measurements ofMnandMwpublished in the literature, our measured values do not reach a minimum but rather increase continuously with decreasing temperature of polymerization. This disagreement is most probably due to the phenomenon of molecular aggreg

ISSN:0021-8995    

DOI:10.1002/app.1973.070171010

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

年代:1973

数据来源: WILEY