Mechanical properties of polymers and composites-Nielsen Episode 6 doc
Mechanical properties of polymers and composites-Nielsen Episode 6 doc
... Thus the length of the rubbery
plateau is a function of the number of entanglements per molecule, MIM
e
(10.54. 56. 64 ,65 ).
A more appropriate picture (66 -71) considers that a randomly coiled
chain ... weight and molecular weight distribution, degree of cross-linking,
and of Plasticization. For two-phase and multiphase systems such as semi-
crystalline polymers and poly...
Mechanical properties of polymers and composites-Nielsen Episode 1 doc
... tests:
Rigid polymers 249
E. Effect of temperature 253
F. Rale of testing and the failure envelope 2 56
G. Effect of hydrostatic pressure 2t?3
H. Effect of molecular weight and branching 265
I. Effect of ... t h e mechanical properties of polymers very complex
if it were not for some general phenomena and principles that underlie all
of these various properties...
Mechanical properties of polymers and composites-Nielsen Episode 2 pot
... 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,...
Mechanical properties of polymers and composites-Nielsen Episode 3 potx
... 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, respectively, and (he term ...
expansion coefficient of the free volume. Pressure increases Tg (3 .65 -69 ).
O'Reilly (65 ) found that pressure increases the Tg value of poly(vinyl
acetate) at the rat...
Mechanical properties of polymers and composites-Nielsen Episode 4 pdf
... 10, 1351 (1 966 ).
23. ASTM Standards, 31, 1099 (1 969 ). ASTM STP 463 . 249 (1970).
24. ASTM Standards D648- 56, D/535 -65 T, and D 163 7 -61 , American Society for
Testing and Materials, Philadelphia. ... 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
possi...
Mechanical properties of polymers and composites-Nielsen Episode 5 doc
... 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 moduli are
interrelated, ... applied, and L
o
the unstretched length of the
specimen. Equation (6) also applies to and gives one of the moduli of
anisotropic materials if the applied stress is paralle...
Mechanical properties of polymers and composites-Nielsen Episode 7 pdf
... 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...
Mechanical properties of polymers and composites-Nielsen Episode 8 docx
... elongation
of the model equal to aJE
x
. The equation for subsequent creep recovery
is
where
Creep and Stress Relaxation 67
Creep and Stress Relaxation 65
teresting changes occur in about one decade of ... amount of viscous creep, and in curve 111, viscous flow is a
prominent part of the total creep. The same data were used in Figures 5
and 6, but notice the dramatic, cha...
Mechanical properties of polymers and composites-Nielsen Episode 9 doc
... 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 ( 16) is the sum of the ... 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 ex...
Mechanical properties of polymers and composites-Nielsen Episode 10 ppsx
... independence of strain and time,
for SBR (up to very large strains) and a polyurethanc rubber, llavsky and
Prins (60 ) and co-workers have presented similar explicit results for a series
of polyurethanc ... minutes at
arc postponed to Chapter 5,
(61 ,66 ). Further discussions of
since
describes the shape of the stress-strain curve and we are dealing
here with creep and st...
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