Molecular length

Fig. 2. Left Time average (over T = 200ps) of the molecular length of Butane versus discretization stepsize r for the Verlet discretization. Right Zoom of the asymptotic domain (r < 10 fs) and quadratic fit.

The fully extended molecular length is not representative of the spatial extension that a molecule actually displays. The latter is sensitive to environmental factors, however, so the extended length is convenient for our present purposes to provide an idea of the spatial size of polymer molecules. 

Various support media may be employed in electrophoretic techniques. Separation on agarose, acrylamide, and paper is influenced not only by electrophoretic mobiUty, but also by sieving of the samples through the polymer mesh. The finer the weave of selected matrix, the slower a molecule travels. Therefore, molecular weight or molecular length, as well as charge, can influence the rate of migration. 

Other nylons are made by varying the molecular length of the diamines and the dibasic acids Nylon-fi. in u.ses sebacic acid (10 carbon atoms), nylon-11 uses an acid from castor oil, and nylon-12 uses butadiene. These variations decrease moisture absorption. Other variations use amines with a ring structure, e.g., the aromatic nylons to give polymers with softening points above 577 F,... 

Coran and Patel [33] selected a series of TPEs based on different rubbers and thermoplastics. Three types of rubbers EPDM, ethylene vinyl acetate (EVA), and nitrile (NBR) were selected and the plastics include PP, PS, styrene acrylonitrile (SAN), and PA. It was shown that the ultimate mechanical properties such as stress at break, elongation, and the elastic recovery of these dynamically cured blends increased with the similarity of the rubber and plastic in respect to the critical surface tension for wetting and with the crystallinity of the plastic phase. Critical chain length of the rubber molecule, crystallinity of the hard phase (plastic), and the surface energy are a few of the parameters used in the analysis. Better results are obtained with a crystalline plastic material when the entanglement molecular length of the... 

Fig. 4a-e. Snapshots of configurations taken from the production stages of simulations of GB(3.0, 5.0, 1, 2) at scaled temperatures a 3.00 b 2.19 c 1.49 d 1.00 e 0.50. The molecules are represented hy lines which are shorter than the molecular length the thick lines show the director and their lengths are proportional to the orientational order parameter, P2, for the configuration... 

It is interesting that all three compounds show small angle reflections in the liquid crystalline state which indicates the formation of associates with a length of about twice the molecular length (for CCH5 17.5 A in the crystal phase I, 31.2 A in the Sb phase, and 27.2 A in the nematic phase) [73]. 

The molecular length of both compounds in the crystalline state is 19.6 A. X-ray investigations in the nematic phase of NCS5 showed that dimeric (29.3 A) as well as monomeric (18.6 A) units exist. For SCN5, a value of 21.3 A was obtained for the apparent length of the molecules in the nematic phase [108]. 

If Lp = Lh, the monolayer smectic Ai phase is formed. In the case that Lp > Lh, the layer spacing d exceeds the molecular length L, which corresponds to the formation of the smectic A phase (Fig. lla,b). In the opposite case, Lp < Lh, the layer spacing is less than L, and the flexible hydrocarbon chains just All the space which is determined by the fluorinated tails (Fig. 10c). 

The layer spacing for smectic Ad and Cd phases significantly exceeds the molecular length (d/L = 1.35-1.65) and increases as the Ad<= Cd transition is approached from above. However, the temperature variations of the layer spacing in the Cd phase are very small in comparison to the classical smectic A-smectic C transition (Fig. 14). This unique behaviour results from the fact that both the tilt angles for different molecular moieties and the relative... 

FIGURE 18.19 Regulation and orientation of molecular length between the adjacent carbon particles. 

For some of the comparison of theory and experiment it is necessary to be specihc about the molecular length scale a (a very detailed discussion of this quantity can be found in Ref. [47]). The molecular scale denotes the lattice... 

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