React mixture

Mixture theory

The “mixture” theory allows you to combine the molecules and molecular weight distributions from other active React theories, and to output the combined mixture into a BoB polymer configuration file. It does not perform new Monte Carlo simulations but uses those already made.

On opening the theory, one is presented with (apparently) just one parameter, which is


this is the number of bins - equally spaced in \(\log_{10}\text{MW}\) - used for analysis of the molecules. More bins means more resolution in the \(\log_{10}\text{MW}\) axis, but also more noise because there are fewer molecules per bin. Thus, the quality of the curves produced is a compromise between these two factors. Usually 50 bins is quite adequate for a reasonable number of molecules.

The remaining parameters are shown when you press the calculate button, which opens a form looking like:


Whenever React creates a new Monte Carlo simulation, using one of the other theories, it stores the information for that simulation. The second column of the above form lists the parent application, dataset, and theory tab-names of the currently existing React simulation. This should be sufficient information for the user to identify which row of the form corresponds to which theory. The form also gives additional information about how many polymers were generated within that theory, and how many polymers are “saved” for output into a BoB polymer configuration file (a saved molecule stores a complete record of the molecule, including the connectivity of all the arms, an unsaved molecule still retains a record of the total molecular weight, number of branches and g-factor).

In order to create a mixture, the user needs to decide which theories to “include” in the mixture (by clicking on the relevant check-boxes). Then the user needs to decide with what weight ratio to combine these theories.


The values in the ratio boxes need not add up to one - the form calculates the effective weight fractions from the ratios (clicking the “Apply” button shows the result of this - although it is not necessary to do this).


Inputting negative numbers in the ratio boxes, or inputting all zeros, will result in an error message. It isn’t advisable to enter non-numeric values!

Clicking “OK” results in calculation of the MWDs.

Saving to BoB

To save a BoB polymer configuration file corresponding to the mixture, click the save button. The mixture theory first checks to see whether any of the other theories have been modified since the mixture MWD was last calculated - if so, you are prompted to recalculate the mixture MWD (this ensures you don’t save a polymer configuration file which doesn’t correspond to the displayed MWD). Then, a form is displayed which asks you to check that the monomer mass and entanglement molecular weights from the different theories in the mixture are consistent.


Currently, BoB is not designed to cope with mixtures of molecules having different entanglement molecular weights - performing calculations on such mixtures is at your own risk!

On clicking “OK”, a save dialogue box is opened, which allows you to save the polymer configuration file. All “saved” polymers, in all theories included in the mixture, are saved into the file, with weight fractions adjusted to reflect the weight fractions in the mixture.