Orientation radial compression

The compressibility equation involves the radial distribution function even when the system consists of nonspherical particles. We recall that previously obtained relations between, say, the energy or the pressure, and the pair correlation function were dependent on the type of particle under consideration. The compressibility depends only on the spatial pair correlation function. If nonspherical particles are considered, it is understood that g(R) in (3.109) is the average over all orientations (3.105). In the following, we shall remove the bar over g(R). We shall assume that the angle average has been taken before using the compressibility equation. 

Deformation band studies of axially compressed PpPTA filaments revealed two distinct types of kink bands. In filaments that show tangentially splitting bands at an angle of about 55° are observed, whereas in radially split fibers the kink bands are oriented perpendicular to the fiber axis. Hydrogen-bonded planes acting as slip planes and intermicrofibril slip play an important role in the deformation process during axial compression [215]. 

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