Nonlinear Viscoelastic Behavior of Silica-Filled Natural Rubber Nanocomposites

International audienc

Nonlinear Viscoelastic Behavior of Silica-Filled Natural Rubber Nanocomposites

International audienc

Non-linear Viscoelastic Behaviour of Titanium Dioxide and Silica Filled

International audienc

Tensile Stress Relaxation Studies of TiO2 and Nanosilica Filled Natural Rubber Composites

International audienc

Tensile Stress Relaxation Studies of TiO2 and Nanosilica Filled Natural Rubber Composites

International audienc

Presence of vacuoles in natural rubber–Cloisite 15A nanocomposites

We studied natural rubber (NR) filled with frequently used organoclay Cloisite 15A using transmission electron microscopy (TEM), cryoporosimetry, and electron spin resonance (ESR) spectroscopy. Quantitative analysis of the TEM micrographs showed a high level of dispersion without the formation of a rigid filler network. The presence of vacuoles was established on the surface of Cloisite 15A ; this indicated weak filler–matrix interactions. The mechanism of reinforcement is, therefore, discussed. The volume of vacuoles was found to be proportional to the crosslinking density ; this was confirmed with ESR spin-probe method. The shape of the ESR spectra was highly influenced by the presence of vacuoles. In the NR–Cloisite 10A nanocomposites, vacuoles were absent. The strong interactions implied by this result were confirmed by ESR measurements and are discussed further

Spray-dried extracts from Syzygium cumini seeds: physicochemical and biological evaluation

Aqueous extract from seeds of Syzygium cumini (L.) Skeels, Myrtaceae, obtained by dynamic maceration was spray-dried and characterized by its physico-chemical and antihyperglycaemic action. The extract showed to possess high amount of polyphenols, significant in vitro free radical scavenger activity using the DPPH method and an antihyperglycaemic effect in alloxan-induced experimental diabetes. S. cumini spray-dried extracts were obtained using silicon dioxide and cassava starch as adjuvants. The powders showed acceptable flowability, compactability, and low hygroscopicity at 43% relative humidity. Besides, the spray-dried extracts showed in vivo antihyperglycaemic and in vitro scavenger activity comparable to the lyophilized extract. Thus, experimental data indicates that the extract from S. cumini has a relevant activity and that spray-drying could be adequately used to perform the technological processing of S. cumini fluid extracts