Preparation and characterization of polyethylene-based hybrid particles by an environmentally-friendly and aqueous solvent evaporation method

The present paper reports preparation procedure and characterization of micrometer-sized polyethylene (PE)-based hybrid particles containing various amounts of Mg(OH)2 powder treated with different amounts of methylhydrogen polysiloxane (MHS). The PE-based hybrid particles were fabricated by an environmentally-friendly and aqueous solvent evaporation method by employing different kinds of surfactants. The shape, microstructure and other properties of the resultant PE-based hybrid particles were dependent markedly on the changes in composition of raw materials, especially for the amount of MHS used for the treatment of Mg(OH)2 and the kind of surfactant. The particles fabricated by using 1 wt% MHS-treated Mg(OH)2 (ST-1) powder and polyoxyethylene (10) octylphenyl ether (Triton X-100) as a surfactant showed spherical shape and their primary particle sizes were about 4--10 μm, irrespective of the additive amount of ST-1 powder. These particles showed superior properties in terms of the actual content of MHS-treated Mg(OH)2 powder incorporated inside the hybrid particles, particle size distribution and particle shape, in comparison with other particles fabricated by using 5 wt% MHS-treated Mg(OH)2 (ST-5) powder and polyoxyethylene (8) octylphenyl ether (Triton X-114) as a surfactant. This is due to good affinity (average contact angle was 19.4°) between the ST-1 powder and the aqueous phase, i.e. a continuous phase, dissolving Triton X-100. Furthermore, a composite fabricated by employing these PE-based hybrid particles showed uniform and homogeneous distribution of ST-1 powder in the PE matrix

Continuous Membrane Emulsification with Pulsed (Oscillatory) Flow

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Industrial and Engineering Chemistry Research, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see: http://dx.doi.org/10.1021/ie3020457Tubular micrometer pore sized sieve type membranes with internal diameter of 14 mm and length of 60 mm containing uniform pores of diameter 10 and 20 μm were used to generate emulsions of sunflower oil dispersed in water and stabilized by Tween 20 using oscillatory flow of the continuous phase. Drop diameters between 30 and 300 μm could be produced, in a controllable way and with span values of down to 0.4. By using pulsed flow it was possible to provide dispersed phase concentrations of up to 45% v/v in a single pass over the membrane, that is, without the need to recirculate the continuous phase through the membrane tube. It was possible to correlate the drop size produced with the shear conditions at the membrane surface using the wave shear stress equation. The oscillatory Reynolds number indicated flow varying from laminar to substantially turbulent, but the change in flow conditions did not show a notable influence on the drop diameters produced, over what is predicted by the varying wall shear stress applied to the wave equation. However, the 20 μm pore sized sieve type membrane appeared to allow the passage of the pressure pulse through the membrane pores, under certain operating conditions, which did lead to finer drop sizes produced than would be predicted. These through-membrane pulsations could be suppressed by changes in operating conditions: a higher dispersed phase injection rate or more viscous continuous phase, and they did not occur under similar operating conditions used with the 10 μm pore sized sieve type of membrane. Generating emulsions of this size using pulsed continuous phase flow provides opportunities for combining drop generation at high dispersed phase concentration, by membrane emulsification, with downstream processing such as reaction in plug flow reactors