S. G. Mason—A retrospective

Abstract

Without exaggeration one can say that Professor Stanley G. Mason was one of the founders of the science of microrheology. His early interest in this field was aroused when trying to understand the complex behavior of papermaking suspensions, the obvious relevance of which became evident after joining the Pulp and Paper Research Institute of Canada (Paprican) in 1946. Besides his publications with Professor Otto Maass from his thesis work on critical phenomena, his early work deals almost exclusively with the hydrodynamic and colloidal aspects of pulp suspensions. He realized that in order to understand the complexity of such systems, it was necessary to study the properties of the individual pulp fibers that make up the suspension. In this respect the classical work of Jeffery (1922) on the motion of ellipsoidal particles in linear shear flows was extremely relevant. Mason compared a pulp fiber with a long slender spheroid and applied Jeffery's theory to the motion of single suspended fibers. Over the years a large number of papers by Mason and coworkers were devoted to the extensions of Jeffery's work. From this early work came the realization that the properties of suspensions can be understood from a knowledge of the behavior of the suspended particles, a realization which led to the science of microrheology, a term coined first by Mason himself. Mason's early work on papermaking became classical among scientists working in the field of pulp and paper. It led, among other things, to an understanding of the electrokinetic properties