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Spatially resolved degradation in heterophasic / Shulamith Schlick in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 2, N° 5 (01/2005)
[article]
Titre : Spatially resolved degradation in heterophasic Type de document : texte imprimé Auteurs : Shulamith Schlick, Auteur ; Krzysztof Kruczala, Auteur Année de publication : 2005 Article en page(s) : p. 389-397 Note générale : Bibliogr. Langues : Américain (ame) Tags : Tinuvin 770 Etude expérimentale Spectrométrie IR RPE Mécanisme réaction Stabilisation thermique Pipéridine dérivé Stabilisant chaleur Additif Relation formulation propriété Vieillissement Mélange hétérogène Propène polymère Caoutchouc éthylène propène thermoplastique Index. décimale : 667.9 Revêtements et enduits Résumé : Heterophasic propylene-ethylene copolymers (HPEC) containing bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate (Tinuvin 770) as a hindered amine stabilizer (HAS) were thermally aged at 393 and 433 K. Two types of HPEC were examined, containing 25% and 10 % ethylene (E), respectively, as ethylene/propylene rubber (EPR). Electron spin resonance (ESR) spectra of nitroxide radicals in HPEC were studied in the temperature range 100-433 K ; the nitroxides were derived from the HAS and are termed HAS-NO. The results were compared with ESR spectra of the same radicals obtained first by oxidation of Tinuvin 770 and then were doped in HPEC and related homopolymers, polyethylene (PE) and polypropylene (PP) ; these nitroxides are termed spin probes. ESR spectra indicated that HAS-NO and the spin probes reside in a range of amorphous sites differing in their dynamic properties. The relative population of the sites was explained by assuming that the crystalline domains exert a restraining effect on chains located in vicinal amorphous domains. Spatial and temporal effects of the aging process were studied by ESR and ESR imaging (ESRI) of HAS-derived nitroxide radicals, and by FTIR of films prepared by compression molding. 1D ESRI enabled the visualization of an outer region of thickness 100 µm that contained a lower amount of nitroxides, and is believed to result from the loss of the stabilizer by diffusion (blooming) and possibly also in chemical reactions during aging. Two-dimensional spectral-spatial ESRI indicated the presence of nitroxide radicals in two amorphous sites, fast and slow ; the corresponding relative intensity varied with sample depth. Both ESRI and FTIR experiments suggested a faster degradation rate in HPEC containing 25 % E, as compared to 10 % E ; moreover, a larger Tinuvin 770 content in the polymers led to less efficient stabilization. FTIR spectra indicated increased ordering of polypropylene segments in HPEC during aging at 433 K. DOI : 10.1007/s11998-005-0006-x En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-005-0006-x.pdf Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3728
in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 2, N° 5 (01/2005) . - p. 389-397[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 000589 - Périodique Bibliothèque principale Documentaires Disponible Use of reactable light stabilizers to prevent migration and to improve durability of coatings On plastic substrates / Nancy Cliff in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 2, N° 5 (01/2005)
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Titre : Use of reactable light stabilizers to prevent migration and to improve durability of coatings On plastic substrates Type de document : texte imprimé Auteurs : Nancy Cliff, Auteur ; Karlis Adamsons, Auteur ; Phillip V. Yaneff, Auteur ; Cindy Peters, Auteur ; Mouhcine Kanouni, Auteur Année de publication : 2005 Article en page(s) : p. 371-387 Note générale : Bibliogr. Langues : Américain (ame) Tags : Etude expérimentale Durabilité Dégradation photochimique Vieillissement accéléré Pipéridine dérivé Triazine Absorbant UV Stabilisant Additif Relation formulation propriété Peinturage Procédé revêtement Matériau revêtu Elastomère Mélange polymère Oléfine Caoutchouc thermoplastique Index. décimale : 667.9 Revêtements et enduits Résumé : One of the challenges of coating plastic substrates for exterior automotive applications involves the tendency for light stabilizers, which inhibit UV degradation of the coating, to migrate out of the topcoat and into the underlying plastic substrate. The consequent depletion of the stabilizer from the topcoat could account for significantly poorer durability for coatings applied on plastic than on a nonpermeable substrate such as steel. These studies investigate the migration of both nonreactable and reactable UV absorbers (UVAs) and hindered amine light stabilizers (HALS) in fully formulated 2K urethane coatings applied on thermoplastic olefin (TPO) and steel substrates. Extensive migration of the nonreactable stabilizers occurs during accelerated exposure of the cured coating, and this migration correlates with poorer performance on TPO. Functionalization of the stabilizer with a group which covalently reacts into the coating will prevent much of this migration, and the improved degree of retention of the reactable light stabilizers in the topcoat correlates with improved performance on TPO substrates. In addition, stabilizer variables, such as the type and extent of functionalization as well as their chemical structure, have an effect on both the migration and performance of the stabilizers. DOI : 10.1007/s11998-005-0005-y En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-005-0005-y.pdf Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3727
in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 2, N° 5 (01/2005) . - p. 371-387[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 000589 - Périodique Bibliothèque principale Documentaires Disponible