Eur. Phys. J. E 2, 359-365
Viscosity critical behaviour at the gel point in a 3d lattice model
E. Del Gado1 - L. de Arcangelis2 - A. Coniglio1
1 Dipartimento di Scienze Fisiche, Università di Napoli
"Federico II'', INFM Sezione di Napoli, Mostra d'Oltremare pad.
19, 80125 Napoli, Italy
2 Dipartimento di Ingegneria dell'Informazione, Seconda Università di Napoli, INFM Sezione di Napoli, via Roma 29, 81031 Aversa (Caserta), Italy
Received 20 December 1999 and Received in final form 18 February 2000
Within a recently introduced model based on the bond-fluctuation dynamics, we study the viscoelastic behaviour of a polymer solution at the gelation threshold. We here present the results of the numerical simulation of the model on a cubic lattice: the percolation transition, the diffusion properties and the time autocorrelation functions have been studied. From both the diffusion coefficients and the relaxation times critical behaviour a critical exponent k for the viscosity coefficient has been extracted: the two results are comparable within the errors giving , in close agreement with the Rouse model prediction and with some experimental results. In the critical region below the transition threshold the time autocorrelation functions show a long-time tail which is well fitted by a stretched exponential decay.
05.20.-y Classical statistical mechanics - 82.70.Gg gels and sols - 83.10.Nn Polymer dynamics
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