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Frequently Asked Questions

Please let us know your rheology questions and we will try to respond


>I would like to try IRIS for a couple of months. Is that possible?
A: This is done easily. However, we charge a nominal "handling fee" (three month license) that will be applied towards a future purchase of the IRIS license. You will obtain the IRIS hardlock for your PC together with the IRIS software.


>Is there an easy way to get started with IRIS ?
A: The IRIS Rheology Tool Kit comes with an extensive collection of tutorials for self-teaching. A more efficient introduction into IRIS is offered through one of the short courses (see workshops). IRIS tutorials can also be held at your loction. In addition, we suggest to try IRIS for 3 months or start with an annual license. This will give ample time for explorations of IRIS as a powerful tool for rheology research and/or teaching.


>Are there any tutorials available for learning IRIS?
A: Yes, a set of tutorial lectures+practice data is included in the support material that comes with the IRIS code


>How does molecular theory come in?
A: Molecular theory provides predictions that IRIS plots against experimental data. We collaborate with several of the leading theory groups (Masubuchi; Blackwell/McLeish; Wagner)who provide 'engines' for the Rheology Tool Kit. Engines are documented by referencing to the corresponding publications in the open literature. Linear viscoelastic theory was implemented in 2003. Non-linear viscoelasticity was added on June 1, 2004. The Palierne model was added for predicting linear viscoelasticity of emulsions. Simulation is in progress. More engines will be added on a regular pace.


>I need color for my oral presentations and black-and-white pictures for writing reports. How can IRIS help?
A: With a single click, IRIS allows you to switch back and forth between black-and-white and color. Symbols and line patterns adjust automatically.


>Can IRIS read data from any rheometer?
A: Yes, the only requirement is that the data are either in ASCII format or in spreadsheet format. IRIS transforms the data into its own universal format (ASCII). This data standard is ideally suitable for data storage, seamless communication, and archiving.


>I've software that came with my rheometer. Would you please let me know about the additional advantages of the new version of IRIS.
A: IRIS and the rheometer program do overlap to a small degree. Basically, the rheometer (instrument and rheometry software) provides the rheological data; the rheometer software program is designed to let you do careful and versatile experiments. The purpose of IRIS is to make use of the data and to integrate data with theory.


>Do I need the IRIS CD in the drive when running IRIS?
A: A CD with source is not required any more after installation. However, the CD (and also the download from the web) carries additional information (manual, literature, more data) which are not automatically transferred to the PC during installation. These can be transferred as needed but do not affect the operation of IRIS.


>Do I have to license the entire IRIS program even if I only need a small fraction of its functions?
A: The IRIS platform program consists of a base program and the IRIS modules. You always will need the base program, and you can license just that base program. At any time, you can add additional functions 'a la carte'. These functions are assigned to modules.


>What is the purpose of the IRIS modules?
A: Modules are designed for executing specific tasks. Experts who specialize in a topic chosen for implementation as module also write that module. The modules are written for IRIS or are adapted to IRIS. IRIS drives the modules from within IRIS and plots the results that it receives from the modules.


>How do you determine the relaxation time spectrum and the retardation time spectrum in IRIS?
A: We have been using the same method since 1988. The method has been published (Baumgärtel M, Winter HH (1989) Determination of discrete relaxation and retardation time spectra from dynamic mechanical data. Rheol Acta 28:511-519; see also several later papers).


>I have several different rheometers in my lab and would like to compare data. How does IRIS help?
A: It does not matter where the data came from, who performed the experiment, or when the experiments were performed as long as the data get transferred into the universal IRIS format. Only the accuracy of the data matters, and IRIS helps with checking the quality of data (Kramers-Kronig check, self-consistency between instruments and between various material functions). We routinely compare new data with data that may go back 10 years and more.


>I do not own a rheometer but need rheological information for my polymer applications. How can IRIS help in that process?
A: The first step is to obtain rheological data for your polymer (dynamic mechanical, steady shear, creep, step strain, uniaxial extension, equibiaxial extension, ...). For polymers, data are typically over a wide temperature range. Other important parameters are molecular weight, concentration, to name a few. Have these data sent to you in the universal IRIS data format or in any ASCII format. Read the data into IRIS and explore your polymer rheologically. You do not need a rheometer as long as you have access to the raw data.


>I need steady shear viscosity functions. However, my impression is that IRIS has been designed for work with G'G" type data. Is there any use for IRIS in steady shear?
A: No problem if you have steady shear data. Enter columns of any two of the following functions: steady shear viscosity, shear rate, shear stress into IRIS and obtain the fit parameters for Carreau, Cross, Carreau-Yasuda, etc.. Preferably, use data sets from different temperatures and apply time-temperature superposition before calculating the viscosity parameters. If steady shear data are unavailable, get an estimate from the Cox-Merz relation


> I could load a data set of G(t) into IRIS but couldn't do anything with it except just plottig in different ways. How should I proceed from here?
A: G(t) is fine but it does not give you the relaxation time spectrum, at least not in a reliable way. It is most advantageous to use a ( w, G',G") data set for determining the relaxation time spectrum? The spectrum will be needed for further calculations. Calculating the spectrum from G(t) is very difficult (and very ill posed); we tried to avoid this problem


>What are the IRIS 'Radio Buttons' good for?
A: IRIS is able to remember your favorite graph format. After having established a graph format that you plan to use again and again for various samples, you can store the format with the yellow icon under 'add current set under preferred' and give it a name. You can return to that graph format after entering new material data by just pushing the button under the yellow icon. This works like the button on your radio where your favorite stations are memorized.


>can I use my favorite plotting program?
A: Go right ahead. It is easily done since all curves in IRIS graphs can instantly be converted into data tables (explained in manual); cut-and-paste these data wherever you like. We think, however, that IRIS graphics is pretty snazzy. Why not giving it a try in your next report or next talk.


> My labels are inverted (mirror image) and/or some sections of the graph are cut off when transferring a graph into MSWord through the conventional copy-and-paste action. How can I avoid this?
A: It has previously helped to do the following: Go to Tools-Program Options. Below the Tab Clipboard find a checkbox. Click on this box to mark it. Then try the copy-and-paste again.


> Did I understand you well? The program that I downloaded from your web site is the full program, not a demo version?
A: Yes, it is the fully functional program. We do not offer a reduced IRIS version. However, the program comes in a set of modules. You should let us know the functions that are important for your work. We will try to introduce the appropriate modules. Please print out the manual and the info material so that you can assess the full scope of IRIS.


>Can I still get a CD version?
A: We will send you a CD if you request it.


>Do you offer software maintenance?
A: Yes. The maintenance contract costs 20% of the license fee.


>Will there be upgrades?
A: Yes, we plan to upgrade annually (every June 1) for a nominal fee (10% of the license fee). New modules might be issued at that same frequency.


>Can I enroll into an annual license?
A: Yes. Annual licenses get renewed on June 1 each year (if not specified otherwise)


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Information about IRIS: Send your questions and suggestions to IRIS Development at IRISrheo@.yahoo.com