Diffusion and thermodynamic behavior of insect repellant and suntan lotion in automotive leather coatings / Loyd J. Burcham in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. XCIX, N° 5 (05/2004)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. XCIX, N° 5 (05/2004) . - p. 211-219 Titre : Diffusion and thermodynamic behavior of insect repellant and suntan lotion in automotive leather coatings Type de document : texte imprimé Auteurs : Loyd J. Burcham, Auteur ; Hans Krose, Auteur Année de publication : 2004 Article en page(s) : p. 211-219 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The diffusion and thermodynamics of insect repellant and suntan lotion absorption into a series of polyurethane and polyacrylic resins used in leather finishing are examined. Physical testing of these resins applied as crosslinked and uncrosslinked thin-films on leather show that DEET exposure causes drastic reduction in Veslic dry rub fastness (greatly improved with a "desorption period" prior to testing). Reductions in rub fastness of samples exposed to suntan lotion were somewhat less severe than with DEET and were greatly improved by crosslinking, but severe yellowing observed during aging indicates continued degradation by non-volatile penetrants. Effective diffusion coefficients (De) and saturation weight uptake levels at equilibrium (Msat) were calculated from free-film gravimetric sorption experiments. These results indicate very high saturation levels (1000-4000 wt % for DEET absorption, ~200 wt % for suntan absorption) and even total dissolution of uncrosslinked polycaprolactone/polyester-based urethanes in DEET. Interestingly, Deep Woods OFF® (25 % DEET in an ethanol/hydrocarbon-based propellant) had identical saturation values as DEET, but with significantly higher diffusion rates - indicating diffusion promotion by highly volatile propellant solvents that do not remain absorbed in the polymer. More fundamentally, both the diffusion and saturation parameters were found to vary with the glass transition temperature, Tg, where higher Tg polymers exhibit lower diffusivity but higher equilibrium saturation levels. Calculations of sorption levels in thin-films on leather (using De values from free-film experiments) also reveal that surface wear properties degrade long before total saturation is achieved. En ligne : https://drive.google.com/file/d/10uImOEBv5_MMX7akJ1iR8pMxQymJPJxN/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=4195 [article]

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Mechanisms and benefits of upgrading technologies in finishing / Loyd J. Burcham in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. C, N° 6 (06/2005)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. C, N° 6 (06/2005) . - p. 209-216 Titre : Mechanisms and benefits of upgrading technologies in finishing Type de document : texte imprimé Auteurs : Loyd J. Burcham, Auteur ; Diamano Cracco, Auteur Année de publication : 2005 Article en page(s) : p. 209-216 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Upgrading of leather crusts that have been damaged by hide defects such as tick bites, scars, and other imperfections remains a high priority in leather finishing because it enables manufacturers to improve the overall quality of their finished leather. The present study uses surface mapping techniques to characterize samples of upgraded full-grain leathers prepared by reverse roll-coating (RRC) and hand stucco application methods. Specific techniques used for surface characterization included Impulse Thermography for surface thermal properties, FTIR mapping for surface chemical properties, dynamic contact angle mapping for surface tension, and scanning-electron and optical microscopy for surface morphology. It was found that the RRC method results in an upgraded crust surface that exhibits very uniform surface properties across the entire surface and in both defect and non-defect areas. By contrast, hand stucco results in a non-uniform crust surface with extremely discontinuous surface properties between defect and non-defect areas. Moreover, adjustments in the RRC add-on coat weight allow for selective and exclusive defect filling while maintaining constant surface physical and chemical properties outside of defect areas through the presence of a thin binder film across the entire surface. Therefore, while the mechanism of upgrading in hand stucco is simply the filling of defects, the mechanism of RRC upgrading comprises the filling of defects plus homogenization of surface physical and chemical properties. These uniform surface properties created by RRC upgrading provide a unique benefit by "priming" the surface for efficient and uniform application of subsequent basecoats and topcoats. En ligne : https://drive.google.com/file/d/1FSLaE4BG3xcWOJ4gexwhapuJGJoVDPRJ/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=4059 [article]

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