The Effect of Leather Fiber upon Vulcanization Characteristics and Physical-Mechanical Properties of Elastomeric Compounds

In this work, leather fibers were employed as a component of elastomeric compounds based on NBR, CR and EPDM and studied were made on their effects upon curing characteristics and mechanical properties of the prepared compounds. Evaluation of curing characteristics of the compounds demonstrated that leather fibers have no considerable effect on initial viscosity and curing time of the compounds. The study of mechanical properties of the vulcanized compounds showed that inclusion of leather fibers leads to increasing of tensile strength in NBR based compound due to compatibility between NBR and leather fibers. It is also found that increase in tensile strength in NBR compounds depends on the curing system of the compounds. The results of this work showed considerable increase in hardness for all of the prepared compounds. Abrasion resistance and resilience of the compounds were also measured and reported

Amphiphile-Induced Phase Transition of Liquid Crystals at Aqueous Interfaces

Monolayer assemblies of amphiphiles at planar interfaces between thermotropic liquid crystals (LCs) and an aqueous phase can give rise to configurational transitions of the underlying LCs. A common assumption has been that a reconfiguration of the LC phase is caused by an interdigitation of the hydrophobic tails of amphiphiles with the molecules of the LC at the interface. A different mechanism is discovered here, whereby reorientation of the LC systems is shown to occur through lowering of the orientation-dependent surface energy of the LC due to formation of a thin isotropic layer at the aqueous interface. Using a combination of atomistic molecular dynamics simulations and experiments, we demonstrate that a monolayer of specific amphiphiles at an aqueous interface can cause a local nematic-to-isotropic phase transition of the LC by disturbing the antiparallel configuration of the LC molecules. These results provide new insights into the interfacial, molecular-level organization of LCs that can be exploited for rational design of biological sensors and responsive systems.11Nsciescopu