Modern Rheometry: shear and extension


Qian_Huang

Qian Huang

Researcher

Copenhagen University, Denmark

Rheology_course_timetable

Rheology Course Timetable

Salvatore_Costanzo

Salvatore Costanzo

Researcher

University of Naples Federico II, Italy

Course description

The birth of modern rheology dates back to the early 20th century, when E.C. Bingham posed the idea of a new interdisciplinary branch of physics concerned with flow properties and deformation of soft matter. Since then, rheology underwent a rapid evolution, especially in the last 50 years, benefitting from the refinement of experimental techniques due to the technological progress.

The implementation of novel highly-sensitivity transducers and optical encoders has made the measurements of stress and strain more reliable compared to the past. Moreover, the development of commercial rheometers with electronic drives and computers allows for precise control of the experimental conditions. To date, using a modern rheometer is a relatively easy task. However, the probability to encounter problems due to experimental artifacts is high, particularly when performing nonlinear measurements on highly viscoelastic materials.

This short course is designed to introduce the participants to the fundamentals of shear and extensional rheometry, both in linear and nonlinear regime. Therefore, it is appropriate for students and practitioners who deal with rheology of complex materials both in the academic and industrial fields.

The course starts with an introduction to linear and nonlinear viscoelasticity, with emphasis on the description of the basic experiments in oscillatory and transient modes. After the introduction, the principles of rotational shear rheometry are presented. This part starts with the description of the working equations of the most common measuring geometries, i.e. cylindrical Couette, parallel plates and cone-and-plate. Apart from linear measurements, particular focus is devoted to nonlinear transient start-up shear measurements with the so-called cone-partitioned-plate (CPP) geometry, which enables high-shear measurements of melts and concentrated solutions; this part includes the description of both home-made and commercial CPPs, including both the design and mounting and measuring operations, as well as examples of measurements for entangled polymer melts/solutions. The shear part ends with a description of common experimental errors and precautions to avoid artifacts, ranging from a proper sample preparation to the choice of the appropriate experimental geometry and temperature control. The second part of the course focuses on uniaxial extension with the description of state-of-the-art instrumentation, the filament stretching rheometry. More specifically, this part starts with an introduction of extensional rheometers and explains the analysis, working equations and necessary assumptions for the different types of rheometers. Subsequently, the filament stretching rheometer (FSR) for measuring nonlinear extensional rheology is discussed in detail. Examples of experimental data for entangled polymer melts/solutions are provided and interpreted.

Deadline for participation:

31st May 2019
7th June 2019

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