Extended chain segments

Formation of the hydrophobic association between the hydrophobic tip of the Rieske Iron Protein and the hydrophobic ubiquinol-containing site stretches an interconnecting chain segment. This extended chain segment functions as a free-standing tether originating from an anchor in the membrane and bridging... 

The tertiary structure of a-C consists mostly of extended chain segments held together by hydrogen... 

This investigation may be summarized by saying that the retractive forces experienced by highly extended chain segments at room temperature due to conformational changes are small in comparison to the ultimate forces that can be carried by a chain. External hindrances to segment rotation have not been treated here. At present is suffices to state that they will only further diminish the —already — small entropy elastic forces. 

From Table 5.3 it is apparent that the weakest mode of skeleton deformation (4.7 GN/m ) is that derived from the hindered rotation of (non-extended) bonds whereas a fully extended chain segment has a 50 times larger stiffness. The elastic modulus of a partially extended kinked chain, then, is ... 

If a semicrystalline microfibril is subjected to stresses, the resulting deformation will be non-homogeneous at the molecular level. The bulk of the deformation will be born by the amorphous regions. As discussed in Chapter 5 the largest stresses are transferred upon extended chain segments which share the strain imparted onto an amorphous region. The stress induced scission of chains must, therefore, be expected to occur within the amorphous regions. 

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