Polymer molecular interpretations

Boyd, R. H. (1985b) Relaxation processes in crystalline polymers molecular interpretation - a review, Polymer, 26, 1123-1133. 

Boyd, R. N. (1985). Relaxation Processes in Crystalline Polymers.- Molecular interpretation a Review. Polymer, 26(8), 1123-1133. 

Figure 10.13 Further relaxation of the amorphous fraction resulting from translational mobility in the crystal (the latter acquired in the a process). Illustrated in this case is reorganisation of the interface in (a) through shortening of two loops that in (b) permits lengthening of a tight tie chain, which in turn permits more deformation of the amorphous fraction. Also shown is a decorating dipole in the crystal that moves through a number of translational, rotational steps. One such step suffices for dielectric activity. (Reproduced from Boyd, R.H. (1985) Relaxation processes in crystalline polymers - molecular interpretation - a review. Polymer, 26, 1123. Copyright (1985) Elsevier Ltd.)...

Figure 10.16 Strain fields set up by stem displacement accompanying kink inversion. (Reproduced from Boyd, R.H. (1985) Relaxation processes in crystalline polymers - molecular interpretation - a review. Polymer, 26, 1123. Copyright (1985) Elsevier Ltd.)...

Brown, H.R., A molecular interpretation of the toughness of glassy polymers. Macromolecules, 24, 2752 (1991). 

Queslel, J. P. and Mark, J. E. Molecular Interpretation of the Moduli Elastomeric Polymer Networks of Know Structure. Vol. 65, pp. 135—176. 

Another approach, neglecting the details of the chemical structure and concentrating on the universal elements of chain relaxation, is based on dynamic scaling considerations [4, 11], In particular in polymer solutions, this approach offers an elegant tool to specify the general trends of polymer dynamics, although it suffers from the lack of a molecular interpretation. 

Dynamic Mechanical Properties. The dynamic mechanical properties of branched and linear polyethylene have been studied in detail and molecular interpretation for various transitions have already been given, although not necessarily agreed upon in terras of molecular origin.(52-56) Transitions for conventional LDPE (prepared by free radical methods) when measured at low frequencies, are located around +70°C, -20°C and -120°C and are assigned to o, 5, and y transitions respectively. (53) Recently Tanaka et al. have reported the dynamic mechanical properties for a sample of HB which was also prepared by anionic polymerization, but contrary to our system the hydrogenation of the polybutadiene was carried out by a coordinate type catalyst.(12) The transitions reported for such a polymer at 35 Hz are very similar to those of LDPE.(12)... 

In so doing, we shall not discuss the possible biophysical significance of some of the data and considerations presented below. Instead, emphasis will be put on the illustration of experimental results of primary interest from the viewpoint of polymer solution theory and on the existing possibilities for their molecular interpretation. It is hoped that this review will draw attention to the new aspects one encounters in solution studies of nonrandomly coiled macromolecules. 

Many natural polymers are monodisperse (all molecules have the same molecular weight). In this case the ullracentrifuge which separates materials according to their effective density in solutions is a most powerful tool for molecular weight determination. With poly-disperse materials, the interpretation of ultracentrifuge results becomes more complex and widespread application of this method to synthetic polymer molecular weighl determination has not yet been achieved... 

One of the first attempts to find a molecular interpretation of viscoelastic behaviour of entangled polymers was connected with investigation of the dynamics of a macromolecule in a form of generalised Rouse dynamics (Pokrovskii and Volkov 1978a Ronca 1983 Hess 1986). It formally means that, instead of assumption that the environment of the macromolecule is a viscous medium, Brownian particles of the chain are considered moving in a viscoelastic liquid with the stress tensor... 

The theory is not limited in its application to the transient properties of amorphous polymers it can be used to make molecular interpretation and prediction of the dynamic viscoelastic properties of crosslinked polymers [24] as well. According to the Fourier-Laplace transformation, the complex tensile modulus can be separated into the real and imaginary parts... 

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