Mastering time-dependent rheological effects and microstructures in soft composites for rational material processing

The microstructure and consequently the final properties, e.g. mechanical, electrical or diffusion ones, of many soft matter composites can be manipulated by controlling the detailed flow history during their processing or application in the liquid state. Soft matter composites typically do not consist of simple, unstructured phases but often have a structured phase(s) or structured interfaces which can give rise to flow-induced time-dependent behavior, often referred to as thixotropy, due to the reversible changes in these structures caused by flow. The time-scales associated with this stucturization are typically slower than the classical visco-elastic time scales of the components but faster than the slow phenomena due to ageing or degradation. Although these phenomena are known, the effects of the flow and thermal history on the kinetics of microstructure development, responsible for the time-dependent behavior, are not sufficiently understood and thus seldomly exploited. The ultimate goal of the present project is to gain fundamental insight in the physical and physicochemical mechanisms that govern the structure development at all length scales in time-dependent (thixotropic) systems with emphasis on the processing of such materials. As the objective is to elucidate the underlying mechanisms and generate predictive models for the resulting rheology and microstructure, specially designed model systems with tunable parameters will be used for this investigation. The approach that will be followed consists of an in-situ and time resolved analysis of the microstructure development during flow, the tools for which have been partially developed and/or built in house.

Keywords:Soft matter

Disciplines:Ceramic and glass materials, Materials science and engineering, Semiconductor materials, Other materials engineering