Mechanical properties of polymers and composites-Nielsen Episode 13 ppsx

... toCreep and Stress Relaxation 115Crystallinity—about.i to 15% ( 213, 232). The creep of plasticized poly(vinylchloride) polymers as a function of temperature, concentration, and kind of plasticizer ... the value of the two polymers, the blockiness of the chain, the compatibility of the two components, and the morphology of the resulting two-phase system. Thus for di- or triblocks of the AB ... (234), and Sabia and Eirich (243). These last workersalso studied stress relaxation (244). In the case of crystalline polymers, plasticizers and Copolymerization reduce the melting point and the...

Mechanical properties of polymers and composites-Nielsen Episode 1 doc

... Relations of Moduli to Molecular StfyetureA. Effects of molecular weightB_ Effect of cross-linkingC. Effect of crystallinity 13. Copolymerrzation and plasticizationE- Block and graft polymers and ... all of the major mechanical properties of polymers: l_ Molecular weight 2. Cross-linking and branching 3. Crystallinity and crystal morphology 4. Copolymerization (random, block, and ... 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 and determine t h e outcome of various...

Mechanical properties of polymers and composites-Nielsen Episode 2 pot

... bewildering number of mechanical tests and testing instru-ments. 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, and English units. A table of ... some cases. Besides the ASTM standard tests, a number of general reference books have been published on testing and on the mechanical properties of poly-mers and viscoelastic materials (2-7)....

Mechanical properties of polymers and composites-Nielsen Episode 3 potx

... copolymers. the distribution of A A. BB and AB sequences is important in determining Tg ( 1 0 3 . 1 0 5 . 1 0 9 ) . Random copoly mers generally do not have the same Tg values as copolymers of ... empirical constant of Mechanieal Tests and Polymer Transitions 15 Other Tests There are many other type's of mechanical tests in common use. One of the most import tant of these tests is ... 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...

Mechanical properties of polymers and composites-Nielsen Episode 4 pdf

... 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 possibilities. The nature of the mechanical ... 1948. 3. J I), 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. ... 8 and 9 illustrate .schematically some of the possible chain arrangements in crystalline polymers (131 -133 ). If the ordered, crystalline regions are cross sections of bundles of chains and...

Mechanical properties of polymers and composites-Nielsen Episode 5 doc

... all directions. Unoriented amorphous polymers and annealed glasses are examples of such materials. They haveonly one of each of the three kinds of moduli, and since the moduli areinterrelated, ... density of the material making up the beam of totalmass m, P the period of the oscillation, fH the frequency of the vibrationsin hertz or cycles per second, and / the rotary moment of inertia ... V is measured and the Young's mod-ulus E is calculated as follows:where C and D are the width and thickness of the specimen (11,12). Thisflexure test often gives values of the Young's...

Mechanical properties of polymers and composites-Nielsen Episode 6 doc

... 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.e., the type of polymer ... made and there is no equivalent to the characteristic time of Figure 5A).In this section we summarize the effect of structural and compositionalfactors on the modulus of the simplest of amorphous...

Mechanical properties of polymers and composites-Nielsen Episode 7 pdf

... effect of any change in £()jrCopolymers and plasticized materials often show another effect—abroadening of the transition region with a decrease in the slope of themodulus 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 and melting point are ... detail in laterchapters.E. Block and Graft Polymers and PolyblendsIn a few cases mixtures of two polymers are soluble in one another, wherethere is a close match of the solubility parameters or...

Mechanical properties of polymers and composites-Nielsen Episode 8 docx

... used.When the stresses and strains become large and the stress-strain curvebecomes nonlinear, simple descriptions of the response and interconversionsbetween creep and relaxation become increasingly ... unit, which consists of a Hookean spring and a Newtonian dashpot in series as shown in theinsert in Figure 1. The modulus or stiffness of the spring is E, and theviscosity of the dashpot is r\. ... relaxation of a Maxwell model (linear scales), T = 1 s.3Creep and Stress RelaxationI. INTRODUCTIONCreep and stress-relaxation tests measure the dimensional stability of amaterial, and because...

Mechanical properties of polymers and composites-Nielsen Episode 9 doc

... amorphous polymers isor. 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 expansioncoefficients and ... ratio of a viscosity to a modulus, as in the spring-dashpotmodel 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 ... WLF(Williams, Landel, and Ferry) equation, which describes the effect of tem-perature on the time scale of the response.The Boltzmann superposition principle states that the response of amaterial...

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