Poly fatigue behavior

The polyurethane formulation Involved a proprietary crossllnkable system based on poly(propylene glycol) and methylene dllsocyanate (NCO/OH ratio = 1.0). For studies of viscoelastic, energy absorption, and fatigue behavior, the weight fractions of PUMA were 0, 0.25, 0.50, 0.75, and 1.0 for studies of tensile and tear strength, the ratios were 0, 0.10, 0.20, 0.25, 0.30, and 0.40. Reactants were mixed at room temperature, degassed, poured Into a mold, and cured at 60 C for 48 hr. 

Fatigue Behavior of Interpenetrating Polymer Networks Based on Polyurethanes and Poly(methyl methacrylate)... 

Surprisingly, relatively few data have been published on stress-strain, creep, or fatigue behavior. Auskern and Horn (1971) and Manning and Hope (1971) have reported stress-strain relationships for samples of concrete containing up to 12 vol. % poly(methyl methacrylate) see Figure 11.10 (Auskern and Horn, 1971). More comprehensive stress-strain data have been... 

In another experiment, the PCL porous matrix was filled with poly(vinyl alcohol) (PVA) and showed that the presence of the cross-linked PVA inside of the PCL macropores leads to an increase of the Young s modulus (Panadero et al., 2015b). However, the mechanical fatigue behavior predicted by the Morrow s model revealed that the PCL-PVA scaffolds had a poor performance when compared to the PCL samples filled with fibrin and water, likely due to complex changes in the porous sfiucture and local interactions among the different phases, eg, PCL, PVA, and water. 

Although interpenetrating polymer networks (IPNs) are now beginning to be commercially exploited, little is known about many types of engineering behavior, such as fatigue. In this paper, energyabsorbing simultaneous interpenetrating networks (SINs) based on polyether-type polyurethanes (PU) and poly(methyl methacrylate)... 

Poly(4 -vinyl-fraws-benzalacetophenone) was prepared by Unruh 52> by condensation of poly(p-vinyhcetophenone) with benzaldehyde. In his studies Unruh s2> compared the photochemical behavior of poly(4 -vinyl-fraMS-benzalacetophenone) with that of the model compound, 4-ethylbenzalacetophenone. Both the polymer and its model showed typical photoisomerization behavior when irradiated in dilute solution. This behavior of the two species was consistent with the results reported for benzalacetophenone by Lutz, et al. 53<54>. Unruh found, however, that when the trans polymer was photoisomerized to the cis form, the expected complete return to trans form upon addition of acid failed to result. This fatigue or loss was attributed to small amounts of intrachain... 

---