Molecular dynamics modeling of orientation-induced nucleation in short alkanes : toward molecular modeling of flow-induced crystallization in polymers
Name
851443257-MIT.pdf
Description
Full printable version
Size
4.4 MB
Format
Adobe PDF
Checksum (MD5)
a7468310fd3b8c4ccc67c5ab35840722
Author(s)
Đjurdjević, Predrag (Predrag Dragutin)
Advisor(s)
Gregory C. Rutledge and Samuel M. Allen.
Alternative Title
Molecular simulation of primary nucleation and growth from oriented melts in polyethylene
Date Issued
2013
Publisher
Massachusetts Institute of Technology
Abstract
The enhancement of the primary flow-induced nucleation rate in short chain alkanes (C20 and C150) has been examined for different levels of orientation by atomistic molecular dynamics simulations. The nucleation rate has been found to change drastically by varying average molecular orientation and temperature. For example, it is possible to accelerate nucleation kinetics by three orders of magnitude at the same temperature, but varying the average level of orientation (P2 (cos [Theta])) . The size of the critical nucleus has been found to increase with the level of undercooling Tm - T decrease, consistent with the classical nucleation theory. Our atomnistic molecular dynamics simulation model is even tractable at the small levels of undercooling, thus clearly demonstrating the effects of orientation (melt anisotropy) on nucleation kinetics when thermal nucleation is expected to be negligible. Furthermore, we calculate the influence of melt anisotropy on the growth rate. As expected, the growth rate is also altered by melt anisotropy. Furthermore, the growth rate maximum always occurs at the temperature above the nucleation kinetics maximum.
Description
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2013.
Title as it appears in MIT degrees awarded booklet, September 2012: Molecular simulation of primary nucleation and growth from oriented melts in polyethylene. Cataloged from PDF version of thesis.
Includes bibliographical references (p. 59-63).
Subjects
Materials Science and Engineering.
MIT Department
Massachusetts Institute of Technology. Department of Materials Science and Engineering
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