Dynamic mechanical and dielectric relaxations of poly(difluorobenzyl methacrylates)

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dc.contributor.authorDiaz Calleja, R
dc.contributor.authorSanchis, MJ
dc.contributor.authorSaiz, E
dc.contributor.authorMartinez Pina, F
dc.contributor.authorMiranda, R
dc.contributor.authorGargallo, L
dc.contributor.authorRadic, D
dc.contributor.authorRiande, E
dc.date.accessioned2024-01-10T12:05:00Z
dc.date.available2024-01-10T12:05:00Z
dc.date.issued2000
dc.description.abstractThis work reports the mechanical and dielectric relaxation spectra of three difluorinated phenyl isomers of poly(benzyl methacrylate), specifically, poly(2,4-difluorobenzyl methacrylate), poly(2,5-difluorobenzyl methacrylate) and poly(2,6-difluorobenzyl methacrylate). The strength of the dielectric glass-rubber relaxation of the 2,6 difluorinated phenyl isomer is, respectively, nearly three and two times larger than the strengths of the 2,5 and 2,4 isomers. The 2,4 isomer presents a mechanical ct peak the intensity of which is nearly two times that of the other two isomers. Both the mechanical and dielectric relaxation spectra display a subglass process, called gamma relaxation, centered in the vicinity of -50 degrees C at 1 Hz and, in some cases, a subglass beta absorption is detected at higher temperature partially masked by the glass-rubber relaxation. The mean-square dipole moments per repeating unit, [mu 2]/x, measured at 25 degrees C in benzene solutions, are 2.5 D-2, 1.9 D-2, and 5.0 D-2 for poly(2,4-difluorobenzyl methacrylate), poly(2,5-difluorobenzyl methacrylate) and poly(2,6-difluorobenzyl methacrylate), respectively. These results, in conjunction with Onsager type equations, permit to conclude that auto and cross-correlation contributions to the dipolar correlation coefficient may have the same time-dependence. On the other hand, dipole intermolecular interactions, rather than differences in the flexibility of the chains, seem to be responsible for the relatively high calorimetric glass-transition temperature of the 2,6 diphenyl isomer, which is, respectively, nearly 36 degrees C and 32 degrees C above the T-g's of the 2,4 and 2,5 isomers. Molecular Mechanics calculations give a good account of the differences observed in the polarity of the polymers. (C) 2000 John Wiley & Sons, Inc.
dc.fechaingreso.objetodigital03-04-2024
dc.format.extent10 páginas
dc.fuente.origenWOS
dc.identifier.doi10.1002/1099-0488(20000815)38:16<2179
dc.identifier.eissn1099-0488
dc.identifier.issn0887-6266
dc.identifier.urihttps://doi.org/10.1002/1099-0488(20000815)38:16<2179
dc.identifier.urihttps://repositorio.uc.cl/handle/11534/75927
dc.identifier.wosidWOS:000088329700011
dc.information.autorucQuímica;Gargallo L;S/I;98194
dc.information.autorucQuímica;Radic D;S/I;49367
dc.issue.numero16
dc.language.isoen
dc.nota.accesocontenido parcial
dc.pagina.final2188
dc.pagina.inicio2179
dc.publisherWILEY-BLACKWELL
dc.revistaJOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS
dc.rightsacceso restringido
dc.subjectfluorinated polymers
dc.subjectmechanical relaxations
dc.subjectdielectric relaxations
dc.subjectdipole moments
dc.subjectrelaxation mechanisms
dc.subjectPOLYMERS
dc.subjectMODEL
dc.titleDynamic mechanical and dielectric relaxations of poly(difluorobenzyl methacrylates)
dc.typeartículo
dc.volumen38
sipa.codpersvinculados98194
sipa.codpersvinculados49367
sipa.indexWOS
sipa.indexScopus
sipa.trazabilidadCarga SIPA;09-01-2024
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