Segmental and chain dynamics of isotactic polypropylene melts

Logotheti, GE; Theodorou, DN

dc.contributor.author	Logotheti, GE	en
dc.contributor.author	Theodorou, DN	en
dc.date.accessioned	2014-03-01T01:27:13Z
dc.date.available	2014-03-01T01:27:13Z
dc.date.issued	2007	en
dc.identifier.issn	0024-9297	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/18347
dc.subject	Polypropylene	en
dc.subject.classification	Polymer Science	en
dc.subject.other	Dielectric spectroscopy	en
dc.subject.other	Diffusion	en
dc.subject.other	Mathematical models	en
dc.subject.other	Molecular dynamics	en
dc.subject.other	Polymer melts	en
dc.subject.other	X ray diffraction	en
dc.subject.other	Atomistic trajectories	en
dc.subject.other	Rouse model analysis	en
dc.subject.other	Segmental dynamics	en
dc.subject.other	Torsion angles	en
dc.subject.other	Polypropylenes	en
dc.title	Segmental and chain dynamics of isotactic polypropylene melts	en
heal.type	journalArticle	en
heal.identifier.primary	10.1021/ma062234u	en
heal.identifier.secondary	http://dx.doi.org/10.1021/ma062234u	en
heal.language	English	en
heal.publicationDate	2007	en
heal.abstract	The properties of isotactic polypropylene (iPP) melts are investigated via atomistic molecular dynamics (MD) simulations in the isothermal-isobaric (NPT) ensemble. A fully flexible model is developed and validated by comparing predicted volumetric and thermodynamic behavior with available experimental data. Atomic-level packing in the simulated polymer melt is examined through the calculation of an X-ray diffraction pattern. Segmental dynamics is investigated through the reorientation of the methylene C-H bonds and the decorrelation function of torsion angles over a wide range of temperatures and pressures. Predicted correlation times are in reasonable agreement with experimental values derived from13C NMR, QENS, and dielectric spectroscopy measurements. The temperature (7) and pressure (P) effects on the relaxation times are compared by calculating the EV/H ratio, which provides a quantitive measure of the relative importance of P and T on the dynamics. By consistently mapping the atomistic trajectories onto the Rouse model, the dynamical behavior of the polymer on the chain level is investigated. Estimates of the segmental friction factor are derived from both the self-diffusion coefficient and the relaxation times of the first Rouse modes. The zero-shear viscosity is calculated from the friction factor through the Rouse model analysis. © 2007 American Chemical Society.	en
heal.publisher	AMER CHEMICAL SOC	en
heal.journalName	Macromolecules	en
dc.identifier.doi	10.1021/ma062234u	en
dc.identifier.isi	ISI:000244855500063	en
dc.identifier.volume	40	en
dc.identifier.issue	6	en
dc.identifier.spage	2235	en
dc.identifier.epage	2245	en