Photochemical sensing of semicrystalline morphology in polymers: Pyrene in Polyethylene

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Show simple item record Vigil Montaño, Maria Reyes Bravo de Pedro, Julio Dib Zambon Atvars, Teresa Baselga Llidó, Juan 2017-11-13T11:09:07Z 2017-11-13T11:09:07Z 1997-08-25
dc.identifier.bibliographicCitation Vigil, M. R., Bravo, J., Atvars, T. D., & Baselga, J. (1997). Photochemical Sensing of Semicrystalline Morphology in Polymers: Pyrene in Polyethylene. Macromolecules, 30 (17), pp. 4871-4876.
dc.identifier.issn 0024-9297
dc.description.abstract Pyrene was inserted into a low-density polyethylene matrix. Fluorescence spectra as a function of temperature and the differential scanning calorimetry (DSC) trace were recorded simultaneously. Along with the usual vibronic bands, a low-intensity band at 365 nm appears at higher energies with respect to the 0−0 transition in the pyrene fluorescence spectra. The fluorescence intensity of this small band increased with temperature, and an isoemissive point was observed to occur at 368 nm. This emission was interpreted as arising from pyrene molecules located in the outer rigid interfacial region of polymer crystallites. Its temperature-dependent fluorescence was interpreted in terms of electron−phonon coupling; two phonons which coincide with fundamental vibrations of polyethylene were necessary to fit experimental data. Coupling with a high-energy phonon was possible at low temperature, whereas, above the β relaxation temperature, phonon coupling occurs with a lower-energy phonon. The α relaxation was detected as a maximum in fluorescence intensity since above its characteristic temperature, nonradiative processes begin to operate.
dc.description.sponsorship J. Baselga thanks CAM and CICYT (Projects No. 247/92 and MAT 93-0823} for financial support. T.D.Z.A. thanks FAPESP, FINEP, and CNPq (Brazil} for financia} support.
dc.format.extent 6
dc.format.mimetype application/pdf
dc.language.iso eng
dc.publisher American Chemical Society (ACS)
dc.rights © American Chemical Society, 1997
dc.title Photochemical sensing of semicrystalline morphology in polymers: Pyrene in Polyethylene
dc.type article
dc.subject.eciencia Materiales
dc.subject.eciencia Química
dc.rights.accessRights openAccess
dc.relation.projectID Comunidad de Madrid. CAM247/92
dc.type.version acceptedVersion
dc.identifier.publicationfirstpage 4871
dc.identifier.publicationissue 17
dc.identifier.publicationlastpage 4876
dc.identifier.publicationtitle Macromolecules
dc.identifier.publicationvolume 30
dc.identifier.uxxi AR/0000010936
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