Mechanical properties of polymers and composites-Nielsen Episode 8 docx

... used. When the stresses and strains become large and the stress-strain curve becomes nonlinear, simple descriptions of the response and interconversions between creep and relaxation become increasingly ... unit, which consists of a Hookean spring and a Newtonian dashpot in series as shown in the insert in Figure 1. The modulus or stiffness of the spring is E, and the viscosi...

Ngày tải lên: 13/08/2014, 16:21

... bibliographical references and index. ISBN 0 -82 47 -89 64-4 1. Polymers Mechanical properties. 2. Polymeric composites— Mechanical properties. I. Landel. Robert F. II. Title. III. Series: Mechanical engineering ... H5 Vin. Effects of Plasticizcrs and Copolymerization 181 IX. Effect of Molecular Orientation 188 X. Effect of Strength of Intcrmolccular Forced 194 XL Polybl...

Ngày tải lên: 13/08/2014, 16:21

... have traditionally been the most popular and universally used of alt mechanical tests and are described by ASTM standard Vests such as D6 38, D 882 , and D412. These tests can be more difficult ... bewildering number of mechanical tests and testing instru- m ents. Most of these tests are very specialized and have not been officially recognized as standardized tests. So...

Ngày tải lên: 13/08/2014, 16:21

... function of the ratio of segmental mobilities of cross- linked to uncross-linked polymer units and the relative cohesive energy densities of cross-linked and uncross-linked polymer (88 ). The ... by the pairs of polymers polypropylene (T g=1 0 C) and polyisobutylene (Tg = -70 C), and poly(vinyi chloride) (Tg =87 C) and poly(vinylidene chloride) (Tg =- 19°C). The symme...

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... Intersaence, New York. 19 48. 3. J I), Ferry. Viscoelastic properties of Polymers, 3rd ed., Wiley. New York, 1 980 . 4. I , n, Nielsen. Mechanical Properties of Polymers. Van Nostrand Reinhold, New ... behavior of polymers, and since these factors can be varied over a wide range, the mechani- cal properties of crystalline polymers take on a bewildering array of...

Ngày tải lên: 13/08/2014, 16:21

... ease of analysis. In this case The stress thus produced is out of phase with the input by an amount 8: so that cr 0 cos 8 is the component of the stress in phase with the strain and a 0 sin 8 ... all directions. Unoriented amorphous polymers and annealed glasses are examples of such materials. They have only one of each of the three kinds of moduli, and since the...

Ngày tải lên: 13/08/2014, 16:21

... weight and molecular weight distribution, degree of cross-linking, and of Plasticization. For two-phase and multiphase systems such as semi- crystalline polymers and polymer blends, morphology and ... the effects of the operational vari- ables temperature and frequency and of changes in the nature of the pol- ymer is closely tied ty) T K and £ ( , A ,, which set t...

Ngày tải lên: 13/08/2014, 16:21

... effect of any change in £ ()jr Copolymers and plasticized materials often show another effect—a broadening of the transition region with a decrease in the slope of the modulus curve in the region of ... plateau. Plasticizers and Copolymerization also shift the glass transition responses of the amorphous phase of crystalline polymers. In addition, the degree of Crystallinity...

Ngày tải lên: 13/08/2014, 16:21

... amorphous polymers is or. less accurately, using the average value of Au from many polymers, of 4.S x H) ' K \ is the difference between the liquid and glassy volumetric expansion coefficients and ... /,, f 10 K and abftut 100 K above 7^,. Above this temper- ature, for thermally stable polymers, Berry and Fox ( 28) have shown that a useful extension of the WLF equation...

Ngày tải lên: 13/08/2014, 16:21

... chain,] In general, the two sections of the curve in Figure 13 can be represented by an equation of the form (134-1 38, 28) Creep and Stress Relaxation 83 and Halpin ( 58) have similarly reported that ... the value of (r ( . for polyethylenes increased by a factor of about 5 in going from a polymer with a density of 0.920 to a highly crystalline one with a density of 0. 980...

Ngày tải lên: 13/08/2014, 16:21