Keith M. Forward

Free Surface Electrospinning of Fibers Containing Microparticles

Many materials have been fabricated using electrospinning, including pharmaceutical formulations, superhydrophobic surfaces, catalysis supports, filters, and tissue engineering scaffolds. Often these materials can benefit from microparticles included within the electrospun fibers. In this work, we evaluate a high-throughput free surface electrospinning technique to prepare fibers containing microparticles. We investigate the spinnability of polyvinylpyrrolidone (PVP) solutions containing suspended polystyrene (PS) beads of 1, 3, 5, and 10 μm diameter in order to better understand free surface electrospinning of particle suspensions. PS bead suspensions with both 55 kDa PVP and 1.3 MDa PVP were spinnable at 1:10, 1:5, and 1:2 PS:PVP mass loadings for all particle sizes studied. The final average fiber diameters ranged from 0.47 to 1.2 μm and were independent of the particle size and particle loading, indicating that the fiber diameter can be smaller than the particles entrained and can furthermore be adjusted based on solution properties and electrospinning parameters, as is the case for electrospinning of solutions without particles.

Triboelectric charging of lunar regolith simulant

[1] We present an experimental investigation of the triboelectric charging behavior of lunar simulant (JSC-1). Our experimental approach ensures that the JSC-1 particles only make contact to other JSC-1 particles during the charging process (and no other surfaces). The results show that charge segregation occurs such that smaller particles tend to charge negatively and larger particles charge positively. This particle-size-dependent charging follows behavior observed for other single-component granular systems and appears to be universal.