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., τ> 10 sec) correspond to thick fibers whereas thin fibers relax on a much faster time scale (i.e., τ< 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.