Mechanical properties of polymers and composites-Nielsen Episode 9 doc

... 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 ... ratio of a viscosity to a modulus, as in the spring-dashpot model of Figure 1, but each sprint! has the same (shear) modulus, and the steady-flow viscosity T] of equation...

Ngày tải lên: 13/08/2014, 16:21

... Date Nielsen. Lawrence E. Mechanical properties of polymers and composites / Lawrence E. Nielsen. Robert F. Landel. — 2nd ed., rev. and expanded. p. cm. — (Mechanical engineering ; 90 ) Includes bibliographical ... theory 297 IK. Theories of Yielding and Cold- Drawing 299 IV. Impact Strength and Tearing 307 A. Nature of impact tesfs 307 B. Effect of notched 308 C. Ef...

Ngày tải lên: 13/08/2014, 16:21

... 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. Some of these tests, however, ... variety of units are used in reporting values of mechanical tests. Stresses, moduli of elasticity, and other properties are given in such units as MK.S (SI), cgs,...

Ngày tải lên: 13/08/2014, 16:21

... 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 symmetrical polymers have ... empirical rule and by the pressure dependence of Tg The empirical rule is (63.64) where ai and ag arc (he volume coefficients of thermal expansion above and below Tg, resp...

Ngày tải lên: 13/08/2014, 16:21

... York. 194 8. 3. J I), Ferry. Viscoelastic properties of Polymers, 3rd ed., Wiley. New York, 198 0. 4. I , n, Nielsen. Mechanical Properties of Polymers. Van Nostrand Reinhold, New York. 196 2. ... Polymer Sci., 10, 1351 ( 196 6). 23. ASTM Standards, 31, 1 099 ( 196 9). ASTM STP 463. 2 49 ( 197 0). 24. ASTM Standards D648-56, D/535-65T, and D1637-61, American Society fo...

Ngày tải lên: 13/08/2014, 16:21

... exactly 90 ° out of phase with the strain. Since the in-phase component is exactly analogous to thaj of a spring, and the out -of- phase component to that of a viscous response, the ratio of the Figure ... 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 sinc...

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 ... comparisons of the responses of a set of polymers (7,16,54-56). These frequency/time response curves serve to delineate the effects of changes in backbone structure (i....

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

... 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

... nitrogen. Annealing can reduce the creep of crystalline polymers in the same manner as for glassy polymers ( 89, 94,102). For example, the properties of a quenched specimen of low-density polyethylene will ... of 0 .98 0. Reid (80,81) has suggested that for rigid amorphous polymers. should be proportional may be related to the . For brittle polymers, the value of to onset...

Ngày tải lên: 13/08/2014, 16:21