A Novel Dynamic Light-Scattering Method to Determine the Modulus of Gels

Abstract

Abstract Laser light sources currently are employed in numerous remote sensing applications. The following discussion concerns a particular application, namely, the use of laser light to probe the mechanical response of soft gels and, thereby, to measure the storage shear modulus and internal viscosity of a sample. The technique described in this paper was developed for biological investigations (e.g., the study of fibrin clots or cytoplasmic gels). However, it has much wider applicability and has been employed, for example, to study thermoreversible polysaccharide gels, as well as covalently crosslinked polyacrylamide networks. This paper in part is a survey of previous applications, and in part a report of new results. The initial sections contain discussions of the basis of the measurement and its use to ascertain the shear storage modulus. The later sections contain new material relating to detection of dissipative mechanisms which, when certain conditions are satisfied, can be described by a gel viscosity coefficient.