49,287 research outputs found
Branched polymers on branched polymers
We study an ensemble of branched polymers which are embedded on other
branched polymers. This is a toy model which allows us to study explicitly the
reaction of a statistical system on an underlying geometrical structure, a
problem of interest in the study of the interaction of matter and quantized
gravity. We find a phase transition at which the embedded polymers begin to
cover the basis polymers. At the phase transition point the susceptibility
exponent takes the value 3/4 and the two-point function develops an
anomalous dimension 1/2.Comment: uuencoded 9 p. ps-file + 2 ps-figure
Linear Rheological Response of a Series of Densely Branched Brush Polymers
We have examined the linear rheological responses of a series of welldefined, dense, regularly branched brush polymers. These narrow molecular weight distribution brush polymers had polynorobornene backbones with degrees of
polymerization (DP) of 200, 400, and 800 and polylactide side chains with molecular weight of 1.4 kDa, 4.4 kDa, and 8.7 kDa. The master curves for these brush polymers
were obtained by time temperature superposition (TTS) of the dynamic moduli over the range from the glassy region to the terminal flow region. Similar to other long chain branched polymers, these densely branched brush polymers show a sequence of relaxation. Subsequent to the glassy relaxation, two different relaxation processes can be observed for samples with the high molecular weight (4.4 and 8.7 kDa) side chains, corresponding to the relaxation of the side chains and the brush polymer backbone. Influenced by the large volume fraction of high molecular weight side chains, these brush polymers are unentangled. The lowest plateau observed in the dynamic response is not the rubbery entanglement plateau but is instead associated with the steady state recoverable compliance. Side chain properties affect the rheological responses of these
densely branched brush polymers and determine their glassy behaviors
Efficiency of the Incomplete Enumeration algorithm for Monte-Carlo simulation of linear and branched polymers
We study the efficiency of the incomplete enumeration algorithm for linear
and branched polymers. There is a qualitative difference in the efficiency in
these two cases. The average time to generate an independent sample of
sites for large varies as for linear polymers, but as for branched (undirected and directed) polymers, where
. On the binary tree, our numerical studies for of order
gives . We argue that exactly in this
case.Comment: replaced with published versio
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