ISSN:0032-3888    

DOI:10.1002/pen.760090502

出版商:Society of Plastics Engineers, Inc.    

年代:1969

数据来源: WILEY

摘要:

AbstractRheo‐optical techniques for the study of crystalline polymers, developed primarily in the United States and Japan, include dynamic birefringence, X‐ray diffraction, dichroism, light scattering, and fluorescence. These permit the characterization of the rates of orientation of crystals, amorphous regions, and crystalline superstructures. The application of these methods has permitted the formulation of a model for the deformation of crystalline polym

ISSN:0032-3888    

DOI:10.1002/pen.760090503

出版商:Society of Plastics Engineers, Inc.    

年代:1969

数据来源: WILEY

摘要:

AbstractA useful concept in polymer science is the degree of crystallinity—the fraction of the polymer that exists in a relatively ordered state. Methods of determination of the degree of crystallinity using density, infrared, thermal, N.M.R. and X‐ray measurements are examined in light of modern notions of the structure of semi‐crystalline pol

ISSN:0032-3888    

DOI:10.1002/pen.760090504

出版商:Society of Plastics Engineers, Inc.    

年代:1969

数据来源: WILEY

摘要:

AbstractThe fatigue failure of thermoplastics and glass‐reinforced thermoplastics is a function of cyclic stress or deflection level, test frequency, viscoelastic polymer parameters and matrix‐to‐fiber stress transfer. This paper reports an investigation of the modes of high frequency fatigue failure in glass‐reinforced and unreinforced thermoplastics. In particular the effects and control of dissipative heating of a working specimen and the role of efficient matrix‐to‐fiber stress transfer are considered. A test procedure with which the severity of dissipative heating can be continuously followed and controlled during an accelerated fatigue test i

ISSN:0032-3888    

DOI:10.1002/pen.760090505

出版商:Society of Plastics Engineers, Inc.    

年代:1969

数据来源: WILEY

摘要:

AbstractThis discussion will illustrate some of the factors which go into the design of experiments required to solve problems in the field of plastics. Two quite diverse problems were considered. In the first case a series of experiments was described which provided a very general technique for predicting polyethylene flow behavior as a function of shear rate over a wide range of temperatures from a minimum of new data. In this case the experimentation concerned only the viscous aspect of flow and was not limited by the availability of special samples. In the second case it was desired to learn what the effect of a specific molecular structural variable was on the general melt rheological properties of polyethylene. This required the polymerization of special samples followed by detailed characterization by both solution property and melt rheological techniques.

ISSN:0032-3888    

DOI:10.1002/pen.760090506

出版商:Society of Plastics Engineers, Inc.    

年代:1969

数据来源: WILEY

摘要:

AbstractSalts of polyacrylic acid can be fabricated in heated molds using mixed powders of polyacrylic acid and metal oxides. Because of the strong intermolecular forces in these polyelectrolyte salts, they have elastic moduli several times greater than the moduli of conventional plastics. They also have very low coefficients of expansion and high compression strengths. Composites containing metallic and inorganic fillers have also been made and their mechanical properties measured.

ISSN:0032-3888    

DOI:10.1002/pen.760090507

出版商:Society of Plastics Engineers, Inc.    

年代:1969

数据来源: WILEY

摘要:

AbstractEquations have been derived to convert Brabender flow curves to Instron flow curves for practical application purposes. The technique involved is simple and has been described and discussed in detail. Nine pairs of Brabender and Instron flow curves of three different high polymers, each at three operating temperatures, have been found to fit each other quite well. The converted Brabender flow curves overlap a part of the Instron curves and extend the shear range toward the Newtonian flow region. An important consequence of this work is that the Brabender Plastograph can now be regarded as a formal viscometer while still functioning as a miniature of the Banbury mixers used in industry. More work is being done to take advantage of this consequence.

ISSN:0032-3888    

DOI:10.1002/pen.760090508

出版商:Society of Plastics Engineers, Inc.    

年代:1969

数据来源: WILEY

摘要:

AbstractThe flexural fatigue characteristics of boron fiber reinforced epoxy were shown to be strongly dependent on the aspect ratio of the reinforcing fibers. These composites were evaluated in a stiffness limited, constant maximum stress mode. The failure mechanism was found to be a combination of interfacial failure and brittle rupture of the matrix at 45 deg to the axis of the fibers. These fatigue cracks result in debonding of the outer fibers, thereby reducing the effective moment of inertia of the specimen.

ISSN:0032-3888    

DOI:10.1002/pen.760090509

出版商:Society of Plastics Engineers, Inc.    

年代:1969

数据来源: WILEY

摘要:

AbstractDerivative stress‐strain curves at constant strain rate for polyacrylonitrile copolymer fibers have been obtained by simple modification of conventional tensile testing apparatus. These derivative curves, considerably more complex and eventful than stress‐strain curves, have been interpreted as direct records of changes undergone by the apparent Young's modulus during experiments which extend from infinitesimal strain to failure. Analysis of the data shows that these changes in the apparent Young's modulus cannot be accounted for to any significant extent by viscoelastic time effects and must therefore be consequences of the deformation process itself. In the light of this analysis, it is concluded that polyacrylonitrile fibers “soften” considerably in the strain range 0.5–3% and that they exhibit moderate “hardening” in the strain range which extends from ca 3% to the breaking

ISSN:0032-3888    

DOI:10.1002/pen.760090510

出版商:Society of Plastics Engineers, Inc.    

年代:1969

数据来源: WILEY

摘要:

AbstractConstant stress creep and recovery experiments were performed in the nonlinear range under combined tension and torsion on a tubular specimen of polycarbonate. Nonlinear viscoelasticity theory was employed to describe the test results. It was found that the first three orders of stress terms and a power function of time adequately described the experimental results. The modified superposition principle satisfactorily predicted the recovery following creep. Recovery was almost complete in several days following two hours of creep.

ISSN:0032-3888    

DOI:10.1002/pen.760090511

出版商:Society of Plastics Engineers, Inc.    

年代:1969

数据来源: WILEY