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The bond fluctuation model with a bond potential has been applied toinvestigation of the glass transition of linear chains and chains with aregular disposition of small branches. Cooling and subsequent heating curvesare obtained for the chain energies and also for the mean acceptanceprobability of a bead jump. In order to mimic different trends tovitrification, a factor B gauging the strength of the bond potential withrespect to the long-range potential (i.e. the intramolecular or intermolecularpotential between indirectly bonded beads) has been introduced. (A higher valueof B leads to a preference for the highest bond lengths and a higher totalenergy, implying a greater tendency to vitrify.) Different cases have beenconsidered for linear chains: no long-range potential, no bond potential andseveral choices for B. Furthermore, we have considered two distinct values of Bfor alternate bonds in linear chains. In the case of the branched chains,molecules with different values of B for bonds in the main chain and in thebranches have also been investigated. The possible presence of crystallizationhas been characterized by calculating the collective light scattering functionof the different samples after annealing at a convenient temperature below theonset of crystallization. It is concluded that crystallization is inheritedmore efficiently in the systems with branched chains and also for higher valuesof B. The branched molecules with the highest B values in the main chain bondsexhibit two distinct transitions in the heating curves which may be associatedwith two glass transitions. This behavior has been detected experimentally forchains with relatively long flexible branches.

Influence of chain topology and bond potential on the glass transition of polymer chains simulated with the bond fluctuation model