Replication of stochastic and geometric micro structures – Aspects of visual appearance / G. R. Berger in INTERNATIONAL POLYMER PROCESSING, Vol. XXVI, N° 3 (07/2011)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXVI, N° 3 (07/2011) . - p. 313-322 Titre : Replication of stochastic and geometric micro structures – Aspects of visual appearance Type de document : texte imprimé Auteurs : G. R. Berger, Auteur ; Dieter P. Gruber, Auteur ; Walter Friesenbichler, Auteur ; C. Teichert, Auteur ; M. Burgsteiner, Auteur Année de publication : 2011 Article en page(s) : p. 313-322 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Matières plastiques -- Moulage par injection Polycarbonates Polymères cristallins Polypropylène Tags : 'Moulage  injection'  Polypropylène  hautement  cristallin  'Polycarbonate  'Miscrostructures  stochastiques'  'Microstructures  géométriques'  'Aspect  visuel'  'Réplication  microstructures' Index. décimale : 668.4 Plastiques, vinyles Résumé : The surface quality of injection molded parts depends on the processing conditions, the cavity surface structure, the runner system, the used polymer and the part geometry. Different replication of the cavity surface structure to the molded part influences its surface function and visual appearance. A descriptive model of the replication process has been developed, taking into account the thickness of the frozen layer during injection. The expected dependencies were proven by systematic injection molding tests with geometric surface micro structures, having depths of 45 or 100 μm and widths from 400 to 2 000 μm, that were replicated into highcrystalline polypropylene (HCPP) and polycarbonate (PC). The volumetric structure replication ratio increased with rising mold temperature, melt temperature and cavity pressure. As expected, the mold temperature was dominant for very small micro features. The RMS roughness, determined by confocal microscopy and atomic-force microscopy, was found to be a suitable replication parameter for draw-polished to mirrorfinished stochastic cavity surface structures. An abrupt change in wall thickness decelerated the flow front velocity, thus decreased the replicated polymer surface roughness and increased the surface gloss. Moreover, a several micrometer high “surface step” remained, due to the different thicknessdependent shrinkage. This step always ascended from the thicker to the thinner part area. The replication of a mirrorfinished mold surface into HCPP was dominated by morphological effects. Local micro shrinkage differences led to micro sink marks, which affected the surface gloss much more than the mold surface structure. DOI : 10.3139/217.2451 En ligne : https://drive.google.com/file/d/1-0SMNhW1w25G6Z5ldo0iFFVthFdqYNeh/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=12420 [article]

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