This study was performed in order to find out whether there are physically meaningful parameters for computer simulations which are leading to structures comparable with the flocculated network found in polymer systems*. This network of flocculated particles constists of branched chains with only one particle as chain-link. Simulation might help to understand the self-organisation rules, but cannot replace physical and chemical research.
We have chosen the "cellular automata" program available as an interactive version** which allows for about 250.000 different parameters. "Cellular automata" was made and is currently being used for simulating "living cells" (e.g. bacteria) which "become alife" or "die" if and when certain cell neighbours are "alife" or "dead".
Our simulation was made with the understanding, that black dots are not any more "living cells" but "flocculated particles", white (not visible) dots are said to represent dispersed particles (those, which are not built in the network structures). The simulation is running in 2 dimensions, which is a correct representation, because flocculation takes place in effectively 2D only (in the "seams"). It is also correct to work with a creen full of dots (regardless whether black or white), because the real flocculation only starts when and if the seams are "full" of dispersed particles.
The simulation starts with a statistical distribution of black dots (= flocculated particles). It is also possible to start with just 2 black dots anywhere on the screen, it only takes much more iteration steps then. With the notation [-234, +12] it was possible to create a continous network structure of "flocculated particles", which is reversibly reforming to discontinous networks and then oszillating between these two characters in ever new shape. This dynamic process seems to be a correct simulation of the "reality". The parameters can be understood as follows:
This result might help to understand why elongated and branched network structures with only one-particle chain-links are formed in heterogeneous polymer systems and other colloidal sysems.
* cf: "further evidence for a phase
transition..." and SEM pictures therein
further work on the new
simulation model by C. Roselieb and comment to it by B. Wessling
**A. Bunde, M. Meyer, in: "Fractals in Science", Verlag Spektrum 1995
