Achieving high service temperatures with thermoplastic elastomers / R. Himes in ADHESIVES AGE, Vol. 40, N° 4 (04/1997)  

[article]  inADHESIVES AGE > Vol. 40, N° 4 (04/1997) . - p. 28-32 Titre : Achieving high service temperatures with thermoplastic elastomers Type de document : texte imprimé Auteurs : R. Himes, Auteur ; D. R. Hansen, Auteur ; D. L. Shafer, Auteur ; S. L. Fulton, Auteur Année de publication : 1997 Article en page(s) : p. 28-32 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Adhésifs thermofusibles Copolymère styrène-éthylène-butadiène Copolymères séquencés Elastomères thermoplastiques Ether de polyphénylène Faisceaux électroniques Formulation (Génie chimique) Mastics thermofusibles Matières premières Réticulation (polymérisation) Index. décimale : 668.3 Adhésifs et produits semblables Résumé : Styrenic block copolymers are quite useful in many adhesive applications. They can be processed as hot melts at high line speeds or as high solids solution coatings. The thermoplastic nature of the styrene endblocks allows the reversible transition from rigid, reinforcing "physical crosslinks" to a soft, easy processing polymer. At temperatures below the glass transition ([T.sub.g]) of the styrene domains (approximately 95°C), the copolymers exhibit properties of a reinforced vulcanized elastomer with tensile strengths up to 35 Mpa in the neat form. At temperatures above the polystyrene Tg, the network weakens and flow is possible. Thus, most styrenic block copolymer adhesive formulations are limited to service temperatures of [less than or equal to] 90°C. Improvements to the service temperature of styrenic block copolymers have been made by electron beam or UV crosslinking star type block copolymers (1). However, not every application can utilize this technique. Many applications, such as automotive or construction applications, would benefit from adhesives which can be hot melt or solvent applied but which have upper service temperatures in the 100-150 [degrees] C range. Blending with endblock compatible resins is a potential approach. However, most conventional end-block resins cannot raise the glass transition temperature of the styrene endblocks because they have Tgs around the same value as polystyrene. Polyphenylene ether is one of the few polymers that is compatible with polystyrene (2) and that has a glass transition temperature in the range of 130°C to 214°C depending upon the molecular weight (Table I). Adding polyphenylene ether to styrenic block copolymers has been considered before (3, 4, 5, 6), but it has been difficult to commercially practice because of the high viscosities and because of the required high processing temperatures. A new low molecular weight polyphenylene ether, which may be available soon in developmental quantities, shows great promise for easy incorporation into SEBS (styrene-ethylene/butylene-styrene) adhesive systems to significantly increase the service temperature properties. Note de contenu : - Polyphenylene ether - Materials evaluated - Formulations - Service temperature results - Lower viscosity TPEs - Endblock Reinforcing En ligne : https://drive.google.com/file/d/1Z_7h7jHiKKwek8tw5S8ke7prAnG6Htqy/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=20390 [article]

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