Production of Hollow Microspheres from Solid Plastic Granules

Plastic microshells with diameters of up to 1.5 mm have been produced at the Lebedev Physical Institute from solid polymer pellets using heated droptower techniques. We review here the basic processing techniques, outline our theoretical understanding of the process, and present detailed surface finish characterization of several shells. Based on limited data we find that the amplitudes of the surface finish modes are larger than those observed on the smaller (0.5 mm) solution droptower shells at the same mode number. However if the comparison is made at the same wavelength rather than mode number the shells show similar amplitude to the solution droptower shells. This result suggests that surface roughness at a given mode may scale with shell diameter.