PCOL2605 Lecture Notes - Lecture 3: Terminal Velocity, Dispersity, Optical Microscope
23 Oct 2018
School
Department
Course
Professor
Document Summary
Importance of particle size for therapeutic considerations: solids a(cid:374)d po(cid:449)ders flowability, mixing, suspe(cid:374)sio(cid:374)s sedimentation and creaming, crea(cid:373)s a(cid:374)d oi(cid:374)t(cid:373)e(cid:374)ts feels on the skin, stability, inhalation aerosols lung deposition. Structures can be single particles or agglomerates (aggregates are smaller agglomerates). Martins diameter: the length of a line that divides a particle into halves. Feret"s diameter: the length between 2 opposite tangents on opposite sides of the particle. Projected area diameter: the diameter of a circle having the same projected area as the particle of interest. Equivalent volume diameter: the diameter of a sphere having the same volume as the particle of interest. Stokes" diameter: the diameter of a sphere having the same settling velocity as the particle of interest. Aerodynamic diameter: the diameter of a sphere of unit density having the same settling velocity as the particle of interest. Methods of particle sizing: taking a representative sample, critical questions: Overlapping particles or agglomerate mistaken as a large single particle.
