Chain defect

McMahon et al. evaluated the energies of the B- and D-type folds on the (100) and (no) planes to be 12.3 kcal/mole (0.535eV) and 14.6 kcal/mole (0.635eV), 

According to Li and Gilman (1970) the energies of the twist-disclination and wedge-disclination loops are, respectively, 

Considering the shear modulus of PE, // = 0.8 GPa, and the Poisson ratio v = 0.3, we estimate the energy of a dispiration loop to be 

Finally, for the kinetics of lamella thickening it is essential to know the lattice resistance to the motion of dispiration loops. This has been estimated by Reneker and Mazur (1983) to be describable by a diffusion constant 1 x 10 cm /s at 343 K. They consider that dispiration loops are likely to have a thermal equilibrium concentration of roughly one defect per molecule stem in a lamella, or a linear concentration of roughly 10 m  

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Suspension- and emulsion-polymerized PVDF exhibit dissimilar behavior in solutions. The suspension resin type is readily soluble in many solvents even in good solvents, solutions of the emulsion resin type contain fractions of microgel, which contain more head-to-head chain defects than the soluble fraction of the resin (116). Concentrated solutions (15 wt %) and melt rheology of various PVDF types also display different behavior (132). The Mark-Houwink relation (rj = KM°-) for PVDF in A/-methylpyrrohdinone (NMP) containing 0.1 molar LiBr at 85°C, for the suspension (115) and emulsion... 

In termination, unsaturated and saturated ends are formed when the propagating species undergo disproportionation, head-to-head linkages when they combine, and other functional groups may be introduced by reactions with inhibitors or transfer agents (Scheme 1.2). In-chain defect structures (within the polymer molecule) can also arise by copolymerization of the unsaturated byproducts of initiation or termination. 

Branched-chain Defective branched-chain Coma, convulsions, vomiting, respiratoryfailure Diet low in branched-chain amino... 

L. Romaner, A. Pogantsch, P.S. de Freitas, U. Scherf, M. Gaal, E. Zojer, and E.J.W. List, The origin of green emission in polyfluorene-based conjugated polymers on-chain defect fluorescence,... 

Wharton, M., Granger, D. L., and Durack, D. T. (1988). Mitochondrial iron loss from leukemia cells injured by macrophages. A possible mechanism for electron transport chain defects. J. Immunol. 141, 1311-1317. 

Chain defects are often associated with faster degradation. Lesser the uniformity in structure, higher is the rate of hydrolysis... 

Solid hydrocarbon soils can be rapidly removed from the surface of a ZnSe IRE by alkyl polyethylene oxide) surfactants. The removal mechanism involves penetration of a small amount of the surfactant into the hydrocarbon layer, which causes an increase in methylene chain defects in the soil, and displacement of solid soil from the substrate. Solubilization of a large fraction of the solid soil is not required. 

As already pointed out above, electropolymerization has many variables which are difficult to control, and thus the structural parameters of the materials obtained tend to be variable. For example, depending on the electrochemical procedures used for the preparation of polythiophene, the conductivity can vary from 0.1 to 1000 S cm-1. This may be due to chain defects, the orientation of chains and the molecular weight the shorter the chain length, then the lower the conductivity is expected to be, since the conjugation is broken. 

A typical polymerization mechanism by free radicals includes the following steps initiation, propagation, chain transfer, formation of chain defect structure, termination and inhibition, as listed below ... 

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