The UNIFAC group contribution method is used to predict the thermo-physical properties of polymers on the basis of the individual structural groups. Use this window to specify which UNIFAC structural groups make up a polymer segment. Polymer components are defined in terms of these polymer segments.
UNIFAC Structures are optional unless you have selected the UNIFAC Free Volume method in the Thermodynamics Main Window when they are required.
Usage
In the Polymer Segments table on the Definition of Polymer Components Window, enter a Segment Name and push the Enter Data button for UNIFAC Structures.
Category
Select the required Category of structural groups from the drop-down list. This enters the corresponding group numbers into the Group list.
Group
When you click on a group in the list, a picture of its Structure is displayed. This allows you to browse the available structures to find the ones that you want.
Add Group
This button becomes available when you click on a Group. Pressing it inserts the highlighted Group into the table below. You may also add groups by double-clicking on the number in the Group list.
Table of Groups
This shows the defined structure of the Polymer Segment. The entries are as follows:
Group: The number of the selected structural group. This may be entered directly into the field or selected from the Group list. It is advisable to start with the most complex groups and select more elementary groups only when a suitable complex group cannot be found.
Number: The number of occurrences of this group in the polymer segment.
Structure: This shows a picture of the selected structural group. Note that a picture will not appear if an invalid Group number is entered.
See Editing Tabular Data for further information on tabular data entry.
Related topics
PRO/II Components - General Information