Temperature Dependence of Relaxation Spectra for Self-Assembled Fibrillar Networks of 12-Hydroxystearic Acid in Canola Oil Organogels

The temperature dependence, of the mechanical
properties of 12-hydroxystearic acid (12HSA) molecular
gels, was investigated by means of rheometry and electron
microscopy. Application of Tikhonov regularization on the
transients of stress relaxation data of 12HSA gels revealed
the remarkable impact of fiber morphology on the relaxation
spectrum. Relaxation processes with long characteristic
times (i.e., ô>10 sec) correspond to thick fibers whereas
thin fibers relax on a much faster time scale (i.e., ô<1 sec).
Molecular gels crystallized at low temperatures, have variable
fiber lengths and widths, show three relaxation events
as opposed to the high crystallization temperature counterparts
that have uniform fibers and result in fewer relaxation
events. These relaxation events correspond exponentially to
the fiber cross-sectional thickness.