Search results for "Polymer melt"
showing 4 items of 14 documents
Monte-Carlo Simulation of 3-Dimensional Glassy Polymer Melts: Reptation Versus Single Monomer Dynamics
1995
A polymer melt is simulated at finite temperature by the Monte-Carlo method. We use a coarse-grained model for the polymer system, the bond-fluctuation model. Static properties of the melt can be obtained by generating configurations not with single-monomer- dynamics which moves individual monomers locally, but reptation-dynamics which allows collec- tive motion of the chains. This algorithm can produce equilibrated configurations much faster. It is demonstrated that static properties do not differ from those obtained by single-monomer- dynamics. Values of the radius of gyration, the mean square bond length and similar quantities for different temperatures and densities are presented.
Monte Carlo simulations of the polymer glass transition: From the test of theories to material modeling
1997
We present results on the glass transition in polymer melts using Monte Carlo simulations of the bond fluctuation lattice model. There are two questions we address in this work. What is the temperature dependence of the entropy density in such a model polymer melt and how well is it described by theories like the Gibbs-DiMarzio theory of the glass transition? And to what degree is one able to map the Hamiltonian of such an abstract lattice model onto a specific polymer material and use it to model the large scale and long time properties of a realistic polymer melt?
Computer simulations of undercooled fluids and the glass transition
2000
Abstract Two model studies are presented that attempt to describe the static and dynamic properties of glass-forming fluids via molecular dynamics simulations: The first model is an atomistically realistic model of SiO 2 , the second model provides a coarse-grained description of polymer liquids, i.e., typical `fragile' glassformers, while SiO 2 is the prototype of a `strong glassformer'. For both models, attention is given to the questions as to which range of temperatures are properties in equilibrium, and whether such simulations can help to interpret experiments and/or check theoretical predictions. While in the simulation of SiO 2 using the potential of van Beest, Kramer and van Santen…
Die bestimmung des chemischen potentials und des expansionskoeffizienten in mischungen von polydimethylsiloxanen unterschiedlichen molekulargewichts
1976
Wird ein Polymermolekul in einer Polymerschmelze von gleicher chemischer Art aber anderem Molekulargewicht gelost, so ist das geloste Polymermolekul im allgemeinen relativ zum ungestorten statistischen Knauel expandiert. Der Expansionskoeffizient und der zweite osmotische Virialkoeffizient hangen von den Molekulargewichten der beiden Polymeren ab. Die experimentellen Befunde werden durch die Gittertheorie fur athermische Losungen von Polymeren richtig beschrieben. If a polymer molecule is solved within a polymer melt of the same chemical nature but of different molecular weight, the solved polymer molecule in general is expanded as compared with the unperturbed statistical coil. The expansi…