Polymer science amorphous

Amorphous—the word amorphous comes from the Greek work amorphos, which literally means without shape (a- meaning without+morp/ios meaning shape). In polymer science, amorphous refers to a material where the polymer chains arrange themselves in a random, haphazard manner. They are distinctly different from crystalline materials, where the molecules are oriented in a regular, repeating pattern (Figure 3.9). 

Our laboratory has planned the theoretical approach to those systems and their technological applications from the point of view that as electrochemical systems they have to follow electrochemical theories, but as polymeric materials they have to respond to the models of polymer science. The solution has been to integrate electrochemistry and polymer science.178 This task required the inclusion of the electrode structure inside electrochemical models. Apparently the task would be easier if regular and crystallographic structures were involved, but most of the electrogenerated conducting polymers have an amorphous and cross-linked structure. 

Direct evidence of nucleation during the induction period will also solve a recent argument within the field of polymer science as to whether the mechanism of the induction of polymers is related to the nucleation process or to the phase separation process (including spinodal decomposition). The latter was proposed by Imai et al. based on SAXS observation of so-called cold crystallization from the quenched glass (amorphous state) of polyethylene terephthalate) (PET) [19]. They supposed that the latter mechanism could be expanded to the usual melt crystallization, but there is no experimental support for the supposition. Our results will confirm that the nucleation mechanism is correct, in the case of melt crystallization. 

Figure 1.66 Resolution of the X-ray scattering curve of a semicrystalline polyethylene sample into contributions from crystalline (110 and 200 planes) and amorphous components. From F. W. Bilhneyer, Textbook of Polymer Science, 3rd ed. Copyright 1984 by John Wiley Sons, Inc. This material is used by permission of John Wiley Sons, Inc.

Voigt-Martin I H, Wendorff J (1985) Amorphous polymers. In Encyclopedia of polymer science and engineering, vol 1. John WUey, New York, p 789... 

An important objective in materials science is the establishment of relationships between the microscopic structure or molecular dynamics and the resulting macroscopic properties. Once established, this knowledge then allows the design of improved materials. Thus, the availability of powerful analytical tools such as nuclear magnetic resonance (NMR) spectroscopy [1-6] is one of the key issues in polymer science. Its unique chemical selectivity and high flexibility allows one to study structure, chain conformation and molecular dynamics in much detail and depth. NMR in its different variants provides information from the molecular to the macroscopic length scale and on molecular motions from the 1 Hz to 1010 Hz. It can be applied to crystalline as well as to amorphous samples which is of particular importance for the study of polymers. Moreover, NMR can be conveniently applied to polymers since they contain predominantly nuclei that are NMR sensitive such as H and 13C. 

Boyer 48) has introduced into polymer science the ACpTg quantity and has found its correlations with some properties of amorphous polymers. It is interesting to compare the data for epoxy-amine networks with those given in Boyer s paper. The... 

Ludovice and Suter can be found in the Encyclopedia of Polymer Science and Engineering. References up to 1988 are included, and techniques such as Monte Carlo, molecular dynamics, and energy minimization are described. In that review, the authors refer to earlier work on glasses and liquids of compounds of low molecular weight in addition to polymeric melts. Most of the material, though, applies to bulk amorphous polymers. 

One of the most important subjects of applied polymer science is the understanding of the deformation mechanisms and the fracture properties of semi-crystalline polymers. At the same time, it is one of the most diffictdt to study, and the amount of research in this area is high (see e.g. One of the complications experienced with semi-crystalline polymers stems from the fact that they are composed of crystalline and amorphous phases, arranged in a diversity of microstructures. These are generally... 

G Williams. Dielectric relaxation spectroscopy of amorphous polymer systems The modern approaches. In E Riande, ed. Keynote Lectures in Selected Topics of Polymer Science. Madrid CSIC, 1995 page 1. 

Boyer, R.F., Transitions and relaxations in amorphous and semicrystalline polymers and copolymers, in Encyclopedia of Polymer Science and Technology, Suppl. Vol. n, John Wiley Sons, 1977, pp. 745-839. 

Figure 17.3. Generalized Modulus-Temperature curves for engineering polymer blends for automotive applications combinations of high amorphous polymers with lower Tg crystalline polymers. Reproduced with permission from L. M. Robeson, in Contemporary Topics in Polymer Science, Vol. 6, Multiphase Macromolecular Systems , B. M. Culbertson, Ed., Plenum Press, New York, 1989.

Fig. 1 Infrared spectrum of amorphous 1,6-polyhexatriene. Reprinted from V. L. Bell, J. Polym. Sci. 2A, 5291 (1964). Copyright 1964 by Oae Journal of Polymer Science. Reprinted by permission of the copyright owner,...

Figure 13.16 Compressive stress-strain data for two amorphous poiymers poiyvinyi chioride (PVC) and cellulose acetate (CA). (From Kaufman, H.S. and Falcetta, J.J., Eds., Introduction to Polymer Science and Technology, John Wiley Sons, New York, 1977. With permisson.)...

Diaz-Calleja. R.. Ricard, E., and Guzman, J.. Influence of static strain on DM behaviour of amorphous networks prepared from aromatic polyesters. J. Polymer. Science. F olymer Physics Edn. 23 (1986). 

Bersted, B. H., and T. G. Anderson. 1990. Influence of molecular weight and molecular weight distribution on the tensile properties of amorphous polymers. Journal of Applied Polymer Science 39 499-514. 

Wang, F.C., Feve, M., Lam, T.M., and Pascault, J.P. (1994) FTIR analysis of hydrogen bonding in amorphous linear aromatic polyurethanes. I. Influence of temperature. Journal of Polymer Science Part B Polymer Physics, 32, 1305-1313. 

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