Nielsen. Lawrence E. Mechanical properties of polymers and composites nielsen doc

[...].. .Mechanical Tests and Polymer Transitions 3 II MECHANICAL TESTS There are a bewildering number of mechanical tests and testing instruments Most of these tests are very specialized and have not been officially recognized as standardized tests Some of these tests, however, have been standardized and are described in the publications of the American Society for Testing and Materials ( 1 ) Many of the... Ferry Viscoelastic properties of Polymers, 3rd ed., Wiley New York, 1980 4 I , n, Nielsen Mechanical Properties of Polymers Van Nostrand Reinhold, New York 1962 5 J V Schinit/., I-'d,, Testing / Polymers, 4 vols., Intcrscicnec, New York, l()h5 and later years fi A- V Titliolsky Properties and Structure uf Polymers, Wiley, New York, ION) 7 K, NilSL-hc and K A Wolf, l-'ds., Sirukiur andphysikulisclies... other of the equations The glass transition of the polymer Is Tg while that of the plasticizer is TgH\ the volume fraction of plasticizer is Fi(b), and its weight fraction js Wg Typical values of T^ are betvaen -50 and - 100°O To calculate more accurate values of Tg additional information must be available, such as the Tg value of a known mixture or the coefficients of thermal expansion (aA and a,,) of" ... behavior of polymers, and since these factors can be varied over a wide range, the mechanical properties of crystalline polymers take on a bewildering array of possibilities The nature of the mechanical property changes is discussed in subsequent chapters The degree of crystallinity is generally measured by x-ray diffraction techniques- ( 1 1 7 1 1 9 ) or by measuring density (117,120,121), but some' mechanical. .. the special type of information required by a research problem The tests may not even correlate with practical use tests in some cases Besides the ASTM standard tests, a number of general reference books have been published on testing and on the mechanical properties of polymers and viscoelastic materials (2-7) Unfortunately, a great variety of units are used in reporting values of mechanical tests... unsymmetrical polymers Thus syndiotactic and isoitactic poly( methyl methacrylate) have Tg values of 115 and 45 C respectively T h e flexibility and cohesive energy density or polarity of each group arc nearly independent of the other groups in the molecule to which they are attached ( 5 5 60).because of this, each group can be assigned an apparent Tg value, and t h e Tg value of a polymer becomes Che sum of. .. value of y is not- constant, 10 Chapter 1 D, Dynamic Mechanical Tests A fourth type of test is known as a dynamic mechanical test Dynamic mechanical tests measure the response of a material to a sinusoidal or other periodic stress Since the stress and strain are generally not in phase, two quantities can be determined: a modulus and a phase angle or a damping term There arc many types of dynamic mechanical. .. characteristic of a polymer as far as mechanical properties are concerned Many other physical properties change rapidly with temperature in the glass transition region These properties include coefficients of thermal expansion (25.26) heat capacity (25,27), refractive index (2S), mechanical damping (4), nuclear magnetic (29) and electron spin resonance behavior (30,31") electrical properties (32-35), and tensile... model of crystalline polymers (Pram Ref 131, ) constant, and AHu the heat of fusion per mole of crystalline polymer repeating unit Copolymerization usually lowers the melting point by shortening the length of crystallizable sequences For random copolymers the lowering of the melting point is (138) where XA is the mole fraction of the crystallizable comonomer A in the copolymer Solvents and plasticizer also... 9 Types of chain ordering and folding which are possible within and between lamellae and between ribbon surfaces In real, well-crystallized polymers, these variations he relatively far apart and the forms SC" CF, SB and A predominate (From Kef, 132.) to the equation (138.140) The molar volume of the polymer repeat unit is Vu V, is the molar volume of the solvent, fi, is the volume Fraction of the solvent, . Library of Congress Cataloging-In-Publitation Date Nielsen. Lawrence E. Mechanical properties of polymers and composites / Lawrence E. Nielsen. Robert F. Landel. — 2nd ed., rev. and expanded. p moisture content There is a strong dependence on temperature and time of the properties of polymers compared to those of other materials such as metals. This strong dependence of properties on. 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, have been standardized and