MECHANICAL PROPERTIES OF POLYMERS AND COMPOSITES pot

[...].. .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... 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. .. shape of the potential wells for bond rotations This effect is illustrated 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 lower glass transition temperatures than the unsymmetrical polymers deSpite the extra side group, although polystyrene (100 C) and poly(a-methylstyrene)... of mechanical tests Stresses, moduli of elasticity, and other properties are given in such units as MK.S (SI), cgs, and English units A table of conversion factors is given in Appendix II A Creep Tests Creep tests give extremely important practical information and at the same time give useful data on those interested in the theory of the mechanical properties of materials As illustrated in Figure... transition temperature of a polymer A typical example is the use of dioctyl phthalate in poly(vinyl chloride) to convert the polymer from a rigid material to a soft, flexible one It the glass transition of the two components A and B are known, an estimate can be made of the Tg value of the mixture by one or the other of the equations The glass transition of the polymer Is Tg while that of the plasticizer... 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" the pure components in both their liquid and glassy states (51,95) For each Component... 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 . 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 THE UNITED STATES OF AMERICA MECHANICAL PROPERTIES OF POLYMERS AND COMPOSITES SECOND EDITION,REVISED AND EXPANDED LAWRENCE E.NIELSEN Monsanto Company St. Louis. Missouri F. LANDEL Jet Propulsion. cm. — (Mechanical engineering ; 90) Includes bibliographical references and index. ISBN 0-8247-8964-4 1. Polymers Mechanical properties. 2. Polymeric composites Mechanical properties. I. Landel.