The correlation between the vibrational dynamics, as sensed by the Debye-Waller factor, and the primary relaxation in the presence of secondary Johari-Goldstein (JG) relaxation, has been investigated through molecular dynamics simulations. Two melts of polymer chains with different bond length, resulting in rather different strength of the JG relaxation are studied. We focus on the bond-orientation correlation function, exhibiting higher JG sensitivity with respect to alternatives provided by torsional autocorrelation function and intermediate scattering function. We find that, even if changing the bond length alters both the strength and the relaxation time of the JG relaxation, it leaves unaffected the correlation between the vibrational dynamics and the primary relaxation. The finding is in harmony with previous studies reporting that numerical models not showing secondary relaxations exhibit striking agreement with experimental data of polymers also where the presence of JG relaxation is known.

Coincident correlation between vibrational dynamics and primary relaxation of polymers with strong or weak johari-goldstein relaxation

Tripodo A.;Puosi F.;Malvaldi M.;Capaccioli S.;Leporini D.
2020-01-01

Abstract

The correlation between the vibrational dynamics, as sensed by the Debye-Waller factor, and the primary relaxation in the presence of secondary Johari-Goldstein (JG) relaxation, has been investigated through molecular dynamics simulations. Two melts of polymer chains with different bond length, resulting in rather different strength of the JG relaxation are studied. We focus on the bond-orientation correlation function, exhibiting higher JG sensitivity with respect to alternatives provided by torsional autocorrelation function and intermediate scattering function. We find that, even if changing the bond length alters both the strength and the relaxation time of the JG relaxation, it leaves unaffected the correlation between the vibrational dynamics and the primary relaxation. The finding is in harmony with previous studies reporting that numerical models not showing secondary relaxations exhibit striking agreement with experimental data of polymers also where the presence of JG relaxation is known.
2020
Tripodo, A.; Puosi, F.; Malvaldi, M.; Capaccioli, S.; Leporini, D.
File in questo prodotto:
File Dimensione Formato  
polymers-12-00761-v2.pdf

accesso aperto

Descrizione: Articolo principale
Tipologia: Versione finale editoriale
Licenza: Creative commons
Dimensione 8.39 MB
Formato Adobe PDF
8.39 MB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11568/1069802
Citazioni
  • ???jsp.display-item.citation.pmc??? 2
  • Scopus 6
  • ???jsp.display-item.citation.isi??? 6
social impact