Meander model

Fig. 5.10 Proposed structures for the noncrystalline regions of polymers (a) the bundle model, (b) the meander model and (c) the random-coil model, ((a) and (c) reprinted by permission of Kluwer Academic Publishers (b) reprinted by permission of John Wiley Sons, Inc.)...

W. Pechhold Meander model, with defective bundle structure, with meander-like folds (h,i)... 

Figure 5.5 Models of the amorphous state in pictorial form, (a) Flory s random coil model the (b) Privalko and Lipatov randomly folded chain conformations (c) Yeh s folded-chain fringed-micellar model and (d) Pechhold s meander model. Models increase in degree of order from (a) to (d). References, (a) P. J. Flory, Principles of Polymer Chemistry, Cornell University Press, Ithaca, NY, 1953. (b) V. P. Privalko and Y. S. Lipatov, Makromol. Chem., 175, 641 (1972). (c) G. S. Y. Yeh, J. Makoromol. Scl. Phys., 6, 451 (1972). (cf) W. Pechhold, M. E. T. Hauber, and E. Liska, KolloIdZ. Z. Polym., 251, 818 (1973). W. Pechhold, lUPAC Preprints, 789 (1971).

Pechhold et al. [31,32] developed and defined the concept of free volume for the molecular dynamics of amorphous and semicrystalline polymers. Their Meander model considers that the polymer chains are arranged in bundles, which can form a meander cube in a three-dimensional volume, as shown schematically in Figure 26.2. 

The temperature dependence of the molecular dynamics of a-relaxation processes can be well described by the Meander model [31-33] ... 

The mathematical representation of the elastic behavior of oriented heterogeneous solids can be somewhat improved through a more appropriate choice of the boundary conditions such as proposed by Hashin and Shtrikman [66] and Stern-stein and Lederle [86]. In the case of lamellar polymers the formalisms developed for reinforced materials are quite useful [87—88]. An extensive review on the experimental characterization of the anisotropic and non-linear viscoelastic behavior of solid polymers and of their model interpretation had been given by Hadley and Ward [89]. New descriptions of polymer structure and deformation derive from the concept of paracrystalline domains particularly proposed by Hosemann [9,90] and Bonart [90], from a thermodynamic treatment of defect concentrations in bundles of chains according to the kink and meander model of Pechhold [10—11], and from the continuum mechanical analysis developed by Anthony and Kroner [14g, 99]. 

Concerning the Frenkel model for structure in the melt, he has not presented a formalized model nor given any details about the nature of segment-segment contacts which "melt out" at Tn-My concept of his model (shown as Fig. 11) is far simpler than the Pechhold meander model [W-R-Pechhold and H.P. Grossman, Faraday Disc., Chem. Soc., 68,58-77 (1979)]. 

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