TRANSITION-STATE ANALYSIS FOR FRACTURE NUCLEATION IN POLYMERS - THE LENNARD-JONES CHAIN

We present here a microscopic theory for fracture nucleation in finite chains, which may account for results found in simulations and in som e experimental situations. We obtain the characteristic breaking time for an ensemble of one-dimensional Lennard-Jones chains, which is main ly a large prefactor times an Arrhenius rate. We show that the express ion scales well and that the activation energy agrees with the analyti cal results. We show that the delay in the fragmentation is a conseque nce of the long-range time correlation in the relative motion of two a djacent particles. This correlation is responsible for the origin of a self-organized memory as well as the large elongation necessary for i rreversible break to occur. We discuss the possibility of using this s imple theory to understand the main characteristic of fragmentation in more complex and realistic systems. [S0163-1829(98)01717-2].