izpis_h1_title_alt

Diffusion spectrum of polymer melt measured by varying magnetic field gradient pulse width in PGSE NMR
ID Mohorič, Aleš (Avtor), ID Lahajnar, Gojmir (Avtor), ID Stepišnik, Janez (Avtor)

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Izvleček
The translational motion of polymers is a complex process and has a big impact on polymer structure and chemical reactivity. The process can be described by the segment velocity autocorrelation function or its diffusion spectrum, which exhibit several characteristic features depending on the observational time scale—from the Brownian delta function on a large time scale, to complex details in a very short range. Several stepwise, more-complex models of translational dynamics thus exist—from the Rouse regime over reptation motion to a combination of reptation and tube-Rouse motion. Accordingly, different methods of measurement are applicable, from neutron scattering for very short times to optical methods for very long times. In the intermediate regime, nuclear magnetic resonance (NMR) is applicable—for microseconds, relaxometry, and for milliseconds, diffusometry. We used a variation of the established diffusometric method of pulsed gradient spin-echo NMR to measure the diffusion spectrum of a linear polyethylene melt by varying the gradient pulse width. We were able to determine the characteristic relaxation time of the first mode of the tube-Rouse motion. This result is a deviation from a Rouse model of polymer chain displacement at the crossover from a square-root to linear time dependence, indicating a new long-term diffusion regime in which the dynamics of the tube are also described by the Rouse model.

Jezik:Angleški jezik
Ključne besede:nuclear magnetic resonance, diffusion, polymer melts, PGSE method, NMR, Rouse, reptation
Vrsta gradiva:Članek v reviji (dk_c)
Tipologija:1.01 - Izvirni znanstveni članek
Organizacija:FMF - Fakulteta za matematiko in fiziko
Leto izida:2020
Status objave pri reviji:Objavljeno
Verzija članka:Založnikova različica članka
Št. strani:10 str.
Številčenje:Vol. 25, iss. 24, art. 5813
PID:20.500.12556/RUL-134851 Povezava se odpre v novem oknu
UDK:543.429.23
ISSN pri članku:1420-3049
DOI:10.3390/molecules25245813 Povezava se odpre v novem oknu
COBISS.SI-ID:42641411 Povezava se odpre v novem oknu
Datum objave v RUL:04.02.2022
Število ogledov:222
Število prenosov:80
Metapodatki:XML RDF-CHPDL DC-XML DC-RDF
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Gradivo je del revije

Naslov:Molecules
Skrajšan naslov:Molecules
Založnik:MDPI
ISSN:1420-3049
COBISS.SI-ID:18462981 Povezava se odpre v novem oknu

Licence

Licenca:CC BY 4.0, Creative Commons Priznanje avtorstva 4.0 Mednarodna
Povezava:http://creativecommons.org/licenses/by/4.0/deed.sl
Opis:To je standardna licenca Creative Commons, ki daje uporabnikom največ možnosti za nadaljnjo uporabo dela, pri čemer morajo navesti avtorja.
Začetek licenciranja:09.12.2020

Sekundarni jezik

Jezik:Slovenski jezik
Ključne besede:jedrska magnetna resonanca, difuzija, taline polimerov, metoda PGSE

Projekti

Financer:ARRS - Agencija za raziskovalno dejavnost Republike Slovenije
Številka projekta:P1-0060
Naslov:Eksperimentalna biofizika kompleksnih sistemov in slikanje v biomedicini

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