Ultra-high enhancement in the toughness of polyethylene by exfoliated natural clay nanosheets

The full exfoliation of inorganic natural clay was engineered in a nonpolar polyethylene following a novel method without the involvement of any chemical modification to the surface of silicate layers. Tensile results showed that the toughening effect was dependent of strain rates, and the toughness of polyethylene was substantially improved by nearly five times with 0.5 wt % natural clay nanosheets at a strain rate of 0.15 s−1. Toughening mechanism was also discussed based on this new exfoliated syste

High mechanical performance polyurea/organoclay nanocomposites

This study reported that the intercalation of C20 organoclay was achieved in polyurea (PUr) matrices. The significant reinforcement was observed in a highly crosslinked PUr (HPUr), in which the Young’s modulus, stress and elongation at break was improved by ∼40%, ∼110% and ∼50%, respectively, with the addition of 5 wt% C20. The energy dissipation of HPUrs was more than doubled by 5 wt% C20 at the strain of 50% and 100%. It was also found that the reinforcement was not equally significant in a lowly crosslinked PUr, indicating that macromolecular structure of the PUr matrices was important for optimizing the nano-effect in the nanocomposites

Making Non-aqueous High Internal Phase Pickering Emulsions: Influence of Added Polymer and Selective Drying

We report the first example of a non-aqueous (oil-in-oil) Pickering high internal phase emulsion (HIPE) stabilized by chemically modified fumed silica. In this case, a 75 vol % ethylene carbonate (EC)-rich internal phase is emulsified in 25 vol % <i>p</i>-xylene (xylene)-rich continuous phase using interfacial nanoparticles. It is revealed that no phase inversion takes place during the HIPE formation process when using the appropriate wettability of solid particles. Incorporating polystyrene (PS) into xylene enables one-step formation of PS-filled HIPEs in place of a multi-step polymerization of the continuous phase. We observe that the size of droplets changes with the addition of PS, and we associate this with the change in the viscosity of the continuous xylene-rich phase. Drying the pure HIPE results in the selective removal of xylene and coalescence of EC-rich droplets. With the PS in the xylene-rich continuous phase, we show that EC-rich droplets can be retained even though the xylene is evaporated off, and a new semi-solid composite containing both liquid phase and solid phase is formed via this non-aqueous Pickering-HIPE template