7 research outputs found
Reentrant phase diagram and pH effects in cross-linked gelatin gels
Experimental results have shown that the kinetics of bond formation in
chemical crosslinking of gelatin solutions is strongly affected not only by
gelatin and reactant concentrations but also by the solution pH. We present an
extended numerical investigation of the phase diagram and of the kinetics of
bond formation as a function of the pH, via Monte Carlo simulations of a
lattice model for gelatin chains and reactant agent in solution. We find a
reentrant phase diagram, namely gelation can be hindered either by loop
formation, at low reactant concentrations, or by saturation of active sites of
the chains via formation of single bonds with crosslinkers, at high reactant
concentrations. The ratio of the characteristic times for the formation of the
first and of the second bond between the crosslinker and an active site of a
chain is found to depend on the reactant reactivity, in good agreement with
experimental data.Comment: 8 pages, 8 figure
Kinetics of bond formation in crosslinked gelatin gels
In chemical crosslinking of gelatin solutions, two different time scales
affect the kinetics of the gel formation in the experiments. We complement the
experimental study with Monte Carlo numerical simulations of a lattice model.
This approach shows that the two characteristic time scales are related to the
formation of single bonds crosslinker-chain and of bridges between chains. In
particular their ratio turns out to control the kinetics of the gel formation.
We discuss the effect of the concentration of chains. Finally our results
suggest that, by varying the probability of forming bridges as an independent
parameter, one can finely tune the kinetics of the gelation via the ratio of
the two characteristic times.Comment: 8 pages, 9 figures, revised versio