Experimental Case Studies

The two main applications of IRIS are educational and professional. Iris is designed as interactive teaching tool for use in the class room and in teaching laboratories; however, it is equally well suited for the professional work of material scientists:

(1) IRIS for Teaching Using IRIS with a standard projector attached to the PC, the instructor enriches his/her teaching with interactive graphics in class. For example, the IRIS program allows you to perform time-temperature superposition in real time, to calculate the relaxation time spectrum immediately after that, and then to graph of all kinds of material functions. All of this is done within minutes so that teaching proceeds at normal pace. Predictions from analytical expressions (Rouse, Doi-Edwards, BSW) can be pulled in and graphed next to the data for comparison. In this way, the students directly participate in the data processing and then can be asked to follow up with a reading assignment in the accompanying text. Teacher and student jointly explore the beauty and usefulness of linear viscoelasticity. Many variations are possible depending on topic and advancement of the class.

The program is designed so that students with minimal training are able shift and further evaluate experimental data by themselves. This ‘hands-on’ approach allows the student to get a feeling for rheological data, their analysis, and their application. The experiments become tangible and 'real'.

(2) IRIS for the Professional With IRIS, you can analyze and scrutinize rheological data from a wide range of rheometers, design effective experiments, determine the rheological parameters, and use these parameters for flow predictions of interest. The resulting data are the starting point for flow calculations (Polyflow modeling, for instance). The interactive graphics of IRIS visualize differences and common features of materials, detect systematic trends in the relaxation patterns (see for instance the study of Baumgärtel, Schausberger, and Winter, Rheologica Acta 29, 400, 1990), monitor phase transitions, or single out specific relaxation modes. Rheological data get scrutinized for inconsistencies (Winter, 1997). As inconsistencies in the data become apparent, methods can be devised to improve the rheometrical experiment. Large sections of IRIS are devoted to time-temperature superposition, conversion of dynamic data into relaxation time spectra, and linear viscoelastic modeling. Recent additions in IRIS compare these experimental findings with theoretical predictions for well defined classes of materials.

Interactive Support

The IRIS program is written with the intention of navigating the user without much reading of a manual. The help-buttons in the toolbar provide sufficient explanation without disrupting the work with IRIS. At all times, a help text appears in the status bar at the lower edge of your screen (if absent, go to ‘view’ and activate ‘status bar’). Its help text will give direct guidance. You will find many details by opening the program and by just starting to work with IRIS. Only some basic directions are given in the following few manual pages. In the manual, we encourage further explorations with occasional tutorials. Answers to some frequently asked questions can be found in the back of the manual. You will also find a ‘picture tour’ (.PPT file) on the CD. It shows typical graphs which you might encounter during your work with IRIS.

The major part of the IRIS program concerns mechanical spectroscopy as explained in a book chapter on Mechanical Spectroscopy by Mours and Winter (2000), see reference on bottom of this page and copy on CD. The IRIS program together with this book chapter constitutes an effective teaching tool and simultaneously a 'work horse' for the rheology laboratory. Many details are explained systematically in the book chapter and are not repeated here. Some sections of IRIS, however, exceed the realm of mechanical spectroscopy and lead you into a full dialog with viscoelasticity, an all encompassing investigation of the viscoleastic properties of your materials. The data from mechanical spectroscopy are the starting position for this dialog.

Reference: Mours M, Winter HH (2000) Mechanical Spectroscopy. Tanaka T, Ed, Experimental Methods in Polymer Science: Modern Methods in Polymer Research and Technology, Academic Press, San Diego CA. p. 495-546.



























Figure: The dialog with viscoelasticity starts with an experimental data set (left) or with a theoretical prediction (center). Each step in the dialog is accompanied with a graph, and each graph can be converted into a spreadsheet (if so desired) or into an endless array of further graphs.