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The effect of a large amount of precipitated amorphous white silica nanofiller, pre-treated with bis[3-triethoxysilylpropyl-)tetrasulfide (TESPT), on the mechanical properties of a sulfur-cured natural rubber (NR) was studied. TESPT chemically adheres silica to rubber and also prevents silica from interfering with the reaction mechanism of sulfur-cure. The silica particles were fully dispersed in the rubber, which was cured primarily by using sulfur in TESPT, or, by adding a small amount of elemental sulfur to the cure system. The cure was also optimized by incorporating sulphenamide accelerator and zinc oxide into the rubber. The hardness, tear strength, tensile strength, and stored energy density at break of the vulcanizate were substantially improved when the filler was added. Interestingly, these properties were also enhanced when the rubber was cured primarily by using sulfur in TESPT.

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In this study, polylactide (PLA)/montmorillonite (MMT) composites were prepared by melt intercalation technique. Three types of MMT, Cloisite® 30B, Cloisite® Na+ and Cloisite® Ca++DEV were used as fillers. The morphology and mechanical properties of the composite materials were investigated and compared with unfilled PLA, keeping the same thermomechanical history. The morphology of the composite materials was evaluated by small-angle x-ray scattering (SAXS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the tensile properties of these composites were measured by an Instron universal testing machine. The morphology observations showed that the good affinity between the organo-modified clay (Cloisite® 30B) and the PLA was sufficient to form intercalated structure in the nanocomposite. Cloisite® Na+ and Cloisite® Ca++ DEV clays exhibited a modest improvement of the young’s modulus of about 18 % and 17 % respectively, due to poor dispersion in the PLA matrix as well as poor polymer-filler interactions compared to Cloisite® 30B. Compared to those of pure PLA, the PLA/Cloisite® 30B composites showed notable improvement of the Young’s modulus of about 54 %.