Constant temperature microfeature embossing with slowly crystallizing polymers / D. Yao in INTERNATIONAL POLYMER PROCESSING, Vol. XXII, N° 4 (09/2007)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXII, N° 4 (09/2007) . - p. 375-379 Titre : Constant temperature microfeature embossing with slowly crystallizing polymers Type de document : texte imprimé Auteurs : D. Yao, Auteur ; K. R. T. Ramasubramani, Auteur ; P. Nagarajan, Auteur Année de publication : 2007 Article en page(s) : p. 375-379 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : A new microfeature embossing method utilizing a slowly crystallizing mechanism was investigated to eliminate thermal cycling, as needed in standard hot embossing. Poly(ethylene terephthalate) was used as a model system for demonstration. Due to its slow crystallization, amorphous PET film can be made by melt casting onto a chilled roll. The resulting amorphous film was embossed at a constant temperature of 180°C for a period of time comparable to or longer than the polymer’s half-time of crystallization. During constant-temperature embossing, the film is softened first, caused by rubber softening of the amorphous phase, and is then hardened, resulting from the crystallization of the amorphous phase at the same embossing temperature. Since the embossed film is hardened under the constant mold temperature, no cooling is needed. Selected micro features, including circular microchannels and high aspect ratio microribs, were consistently patterned using a total cycle time about 40s. The embossed films were characterized using DSC and rotational rheometry to elucidate the physical mechanism for softening and hardening the polymer during constant-temperature embossing. DOI : 10.3139/217.2047 En ligne : https://drive.google.com/file/d/1lZUYqJQ8yDYOII-dteV_tO2Y5vNaIiYb/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2701 [article]

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The role of surfactant on the film formation of latex polymers / P. Nagarajan in PAINTINDIA, Vol. XLVI, N° 2 (02/1996)

[article]  inPAINTINDIA > Vol. XLVI, N° 2 (02/1996) . - p. 19-24 Titre : The role of surfactant on the film formation of latex polymers Type de document : texte imprimé Auteurs : P. Nagarajan, Auteur ; C. K. Mital, Auteur ; M. K. Trivedi, Auteur Année de publication : 1996 Article en page(s) : p. 19-24 Note générale : Bibliogr. Langues : Anglais (eng) Tags : Latex  'Réseau  polymère  interpénétré'  'Méthacrylate  méthyle  polymère'  'Acrylate  butyle  'Méthacrylique  acide  'Système  ternaire'  'Formation  film'  'Agent  surface'  'Propriété  'Tension  superficielle' Index. décimale : 667.9 Revêtements et enduits Résumé : Two different latex interpenetrating polymer networks (LIPNs), comprising of polyacrylate (methyl methacrylate: n-butyl acrylate: methacrylic acid-43:57: 2.5) as seed and second polymer as polystyrene and polymethyl methacrylate, having a difference in hydrophilicity have been prepared. Surface tension measurements, were carried out to demonstrate the difference in adsorption equilibria of the anionic surfactant, sodium dodecyl sulphate on the different latex particles, with change in pH. the films were cast at different pHs, and it was found that the film of styrene based LIPN at a low pH (3.3), yielded translucent film while transparent films were also obtained from styrene based LIPN at a higher pH of 9, neutralized with NaOH. The higher strength of the latex films, obtained at the pH of 9 than those obtained at pH 3.3 of the styrene based LIPNs, indicates that the reduction in the polymer-water interfacial tension enhances the coalescence. It has been demonstrated clearly by the experimental evidence, that adsorption of surfactant on polymer, in styrene based latexes and the exudation of the surfactant in MMA based latexes, results in major difference in the optical clarity of the latex films. Note de contenu : - Preparation of LIPNs - Surface tension measurements - Transparency of the films - Tensile strength - Spectral measurements Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=13390 [article]

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