scholarly journals Understanding the Molecular Dynamics of Dual Crosslinked Networks by Dielectric Spectroscopy

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3234
Author(s):  
Saul Utrera-Barrios ◽  
Reyes Verdugo Manzanares ◽  
Javier Araujo-Morera ◽  
Sergio González ◽  
Raquel Verdejo ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Dielectric Spectroscopy ◽  
Abrasion Resistance ◽  
Chemical Resistance ◽  
Ionic Clusters ◽  
Multiple Networks ◽  
Solvent Uptake ◽  
Elastomeric Materials ◽  
Improved Performance ◽  
Synergistic Behavior

The combination of vulcanizing agents is an adequate strategy to develop multiple networks that consolidate the best of different systems. In this research, sulfur (S), and zinc oxide ( ZnO) were combined as vulcanizing agents in a matrix of carboxylated nitrile rubber (XNBR). The resulting dual network improved the abrasion resistance of up to ~15% compared to a pure ionically crosslinked network, and up to ~115% compared to a pure sulfur-based covalent network. Additionally, the already good chemical resistance of XNBR in non-polar fluids, such as toluene and gasoline, was further improved with a reduction of up to ~26% of the solvent uptake. A comprehensive study of the molecular dynamics was performed by means of broadband dielectric spectroscopy (BDS) to complete the existing knowledge on dual networks in XNBR. Such analysis showed that the synergistic behavior that prevails over purely ionic vulcanization networks is related to the restricted motions of rubber chain segments, as well as of the trapped chains within the ionic clusters that converts the vulcanizate into a stiffer and less solvent-penetrable material, improving abrasion resistance and chemical resistance, respectively. This combined network strategy will enable the production of elastomeric materials with improved performance and properties on demand.

scholarly journals Broadband Dielectric Spectroscopy Study of Biobased Poly(alkylene 2,5-furanoate)s’ Molecular Dynamics

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1355 ◽  
Author(s):  
Michelina Soccio ◽  
Daniel E. Martínez-Tong ◽  
Giulia Guidotti ◽  
Beatriz Robles-Hernández ◽  
Andrea Munari ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Dielectric Spectroscopy ◽  
Relaxation Times ◽  
Barrier Properties ◽  
Polymer Processing ◽  
Industrial Applications ◽  
Structure Property ◽  
Property Relations ◽  
Broadband Dielectric Spectroscopy ◽  
Segmental Relaxation

Poly(2,5-alkylene furanoate)s are bio-based, smart, and innovative polymers that are considered the most promising materials to replace oil-based plastics. These polymers can be synthesized using ecofriendly approaches, starting from renewable sources, and result into final products with properties comparable and even better than those presented by their terephthalic counterparts. In this work, we present the molecular dynamics of four 100% bio-based poly(alkylene 2,5-furanoate)s, using broadband dielectric spectroscopy measurements that covered a wide temperature and frequency range. We unveiled complex local relaxations, characterized by the simultaneous presence of two components, which were dependent on thermal treatment. The segmental relaxation showed relaxation times and strengths depending on the glycolic subunit length, which were furthermore confirmed by high-frequency experiments in the molten region of the polymers. Our results allowed determining structure–property relations that are able to provide further understanding about the excellent barrier properties of poly(alkylene 2,5-furanoate)s. In addition, we provide results of high industrial interest during polymer processing for possible industrial applications of poly(alkylene furanoate)s.

scholarly journals Molecular dynamics of a binary mixture of twist-bend nematic liquid crystal dimers studied by dielectric spectroscopy

2016 ◽  
Vol 93 (6) ◽  
Author(s):  
Beatriz Robles-Hernández ◽  
Nerea Sebastián ◽  
Josep Salud ◽  
Sergio Diez-Berart ◽  
David A. Dunmur ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Liquid Crystal ◽  
Binary Mixture ◽  
Nematic Liquid Crystal ◽  
Dielectric Spectroscopy

Molecular dynamics of poly(butylene tert-butyl isophthalate) and its copolymers with poly(butylene terephthalate) as revealed by broadband dielectric spectroscopy

Polymer ◽  
2006 ◽  
Vol 47 (20) ◽  
pp. 7078-7084 ◽  
Author(s):  
Aurora Nogales ◽  
Alejandro Sanz ◽  
Tiberio A. Ezquerra ◽  
Robert Quintana ◽  
Sebastian Muñoz-Guerra
Keyword(s):  
Molecular Dynamics ◽  
Dielectric Spectroscopy ◽  
Butylene Terephthalate ◽  
Tert Butyl ◽  
Broadband Dielectric Spectroscopy

Molecular dynamics of discotic charge-transfer complexes, dielectric spectroscopy and2H NMR studie

1994 ◽  
Vol 17 (3) ◽  
pp. 381-395 ◽  
Author(s):  
M. Möller ◽  
J. H. Wendorff ◽  
M. Wert ◽  
H. W. Spiess ◽  
H. Bengs ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Charge Transfer ◽  
Dielectric Spectroscopy ◽  
Charge Transfer Complexes

Molecular dynamics in semifluorinated side-chain polyesters as studied by broadband dielectric spectroscopy

Polymer ◽  
2006 ◽  
Vol 47 (20) ◽  
pp. 7189-7197 ◽  
Author(s):  
Julius Tsuwi ◽  
Lutz Hartmann ◽  
Friedrich Kremer ◽  
Doris Pospiech ◽  
Dieter Jehnichen ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Dielectric Spectroscopy ◽  
Side Chain ◽  
Broadband Dielectric Spectroscopy

Molecular Dynamics of Linear and Crosslinked Polyester Urethanes Studied by Dielectric Spectroscopy

2011 ◽  
Vol 43 (6) ◽  
pp. 559-576 ◽  
Author(s):  
S. Oprea ◽  
V.-E. Musteata ◽  
V. O. Potolinca
Keyword(s):  
Molecular Dynamics ◽  
Dielectric Spectroscopy ◽  
Charged Particles ◽  
High Mobility ◽  
Charge Carriers ◽  
Chemical Crosslinking ◽  
Elastic State ◽  
Segmental Mobility ◽  
Relaxation Temperature ◽  
Mobility Of Charge Carriers

The molecular dynamics of crosslinked polyurethanes have been studied by dielectric spectroscopy and compared with the dynamics of linear polyurethanes. Two local relaxations, γ and β, and a primary relaxation, α, were observed for all the samples, appearing in relation with the increase in temperature. The conductivity was studied at temperatures higher than the glass transition temperature and it was found to decrease with the increasing content of crosslinker. The presence of crosslinks strongly influences their dielectric properties, especially in the elastic state. The linear polyurethane exhibits the lowest α-relaxation temperature. For the crosslinked samples, α-relaxation temperature increases with increase in the amount of crosslinkers; β- and γ-relaxations are less affected by chemical crosslinking and their activation energies are in the ranges 40–55 and 34–37 kJ/mol, respectively. For the linear polyurethane, there is an exception in the case of the γ-relaxation, which has a higher activation energy determined by its physical crosslinks. Conductivity analysis reveals a high mobility of charge carriers and low barriers for the transport of the charged particles. Also, the conductivity process is dependent on the segmental mobility of polymers.

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