2014 Fiscal Year Research-status Report
Unified View of Entanglements in Polymer Liquids
| Project/Area Number |
26800221
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| Research Institution | Yamagata University |
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Principal Investigator |
SUKUMARAN S.K. 山形大学, 理工学研究科, 准教授 (70598177)
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| Project Period (FY) |
2014-04-01 – 2017-03-31
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| Keywords | Entanglements / Polymer Blends / Polymer Melts / Polymer Solutions / Polymer Dynamics |
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| Outline of Annual Research Achievements |
We prepared blends of stiff and flexible chains at different blending ratios. Two different combinations of chain stiffness values were used. At the first stage, both the stiff and the flexible chains had 200 beads each. We then performed topological analysis by length minimization on all of the equilibriated blend configurations. For both of the blends we found that the tube diameters evaluated from the primitive path configurations of both the stiff and the flexible chains were almost equal to each other. This finding suggests that both the stiff and the flexible chains experience almost identical topological constraints in the blend.
To understand these results, we have extended entanglement models for homopolymer melts to the case of binary blends. The derived mixing rules were compared to the simulation results. It was found that the results were in general agreement with the extensions of two of the entanglement models. The current results are unable to distinguish between the predictions of the two models. This will be one focus of future work.
In addition, the simulation results were compared to the mixing rules available in the literature. The simulation results are in qualitative disagreement with one mixing rule that was proposed based on the analysis of experimental data. Further, it was found that a mixing rule derived using double reptation ideas could be reinterpreted and better theoretical foundation provided using ideas from the packing models of entanglements. A better understanding of these results will be anothe focus of future work.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
Past experience with equilibriating polymer configurations in the melt state, molecular dynamics and various types of topological analysis helped us avoid common pitfalls and enabled reasonable progress. The additional computational capacity provided by this funds to this project has been really helpful to our numerical efforts and has helped us achieve greater progress over the past couple of months.
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| Strategy for Future Research Activity |
First, we will perform topological analysis through energy minimization and compare the results from length minimization. We will repeat our analysis for longer chain lengths (first, for 300 beads per chain). These two are necessary to ensure that the results obtained are not artifacts observed in just one or two cases.
We will continue to prepare well-equilibriated configurations of the blends of chains of different stiffness values for various chain lengths, perform topological analysis on the blend configurations, calculate the linear rheology of the well-equilibriated binary blends using the simulations and develop theoretical models to elucidate the nature of entanglements in binary blends.
We will theoretically investigate the consequences of the mixing rules developed (already started in Fiscal Year 2014 and to be continued in Fiscal Year 2015) for the linear dynamics of the polymer chains of two different stiffness values in the blends. One focus of this effort will be to theoretically understand the experimentally obtained data for the linear rheology of binary blends, in particular the origin of the discrepancy between the experimentally motivated mixing rule and mixing rules derived from entaglement models. We will also investigate the differences between the various entanglement models.
Finally, using the results of the topological analysis, and the linear dynamics and viscoelasticity obtained from the simulations, we will also attempt gain insights that can be used for the development of slip-link models to describe the linear dynamics of binary polymer blends.
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| Causes of Carryover |
物品の購入を検討していたが年度内に納品できなかったため、翌年度に繰り越した。
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| Expenditure Plan for Carryover Budget |
当該助成金は実験データを保存するストレージの購入資金として予定している。
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