Polymer structure and properties in micro- and nanomolding process

Ito, Hiroshi; Suzuki, Hajime; Kazama, Kunihiko; Kikutani, Takeshi

doi:10.1016/j.cap.2008.12.024

Cited by 26 publications

(9 citation statements)

References 14 publications

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“…Viscosity is a crucial rheological parameter of polymers; it is closely related to the flow properties of the polymer melt. Studies have confirmed that the viscosity of polymer melts in a microcapillary is different from that in a conventional one, and it is affected on different levels by factors such as the geometry characteristics, wall slip, molecular structure, shear rate, and even the heat‐transfer behavior …”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of the rheological behaviors of polypropylene in a capillary flow

Meng

Kelly

et al. 2016

J of Applied Polymer Sci

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The rheological characterization of polymer melts is strongly related to their material properties. In this study, we focused on the rheological behaviors of a polypropylene (PP) melt through a capillary die. With an advanced twin-bore capillary rheometer with dies measuring 1.0, 0.5, and 0.25 mm in diameter, experiments were performed over a shear-rate range of 3 3 10 2 to 5 3 10 3 s 21 at three temperatures, 210, 220, and 230 8C. The results demonstrate that the geometry dependence of the PP viscosity relied on the die diameter and the temperature of the PP melt. The viscosity values of the PP melt in the 0.25-mm diameter die were higher than were those in the 0.5-and 1.0-mm dies at 220 and 230 8C. However, the viscosity values in all of the tested dies were similar at 210 8C. The tendency for the viscosity to decrease as the temperature of the polymer melt increased weakened in the 0.25-mm diameter die. As a result, the pressure applied to the PP melt in the 0.25-mm diameter die increased; this caused a decrease in the free volume between molecules. On the basis of the Barus equation, the contribution of pressure to the changed viscosity in each die at each of the tested temperatures was calculated and was found to be as high as 32.86% in the 0.25-mm die at 230 8C. Additionally, the effect of the wall slip on the geometry dependence of the PP viscosity in the tested dies was investigated with a modified Mooney method. The values of the slip velocity revealed that wall slip occurred only in the 0.25-mm die at 210 8C.

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Section: Introductionmentioning

confidence: 99%

Experimental investigation of the rheological behaviors of polypropylene in a capillary flow

Meng

Kelly

et al. 2016

J of Applied Polymer Sci

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“…On observe d'après ce tableau qu'il n'y a pas un ou deux facteurs identiques qui ressortent comme étant les paramètres les plus importants dans la réplication par injection de textures submicroniques. En effet, la vitesse d'injection (V inj ) semble être le facteur prédominant dans plusieurs études [121,129] alors que dans une autre [47] tous les facteurs semblent influencer de la même manière la qualité de réplique, malgré qu'ils utilisent le même polymère (un PC).…”

Section: Impact Des Paramètres D'injection Sur La Réplicationunclassified

“…La position sur la pièce de la texture à répliquer influence aussi la réplication. Ito et al [47] observent qu'avec du PC, la qualité de réplique est meilleure en fin de pièce (en fonction du sens d'écoulement du polymère dans l'empreinte) (95 %) qu'en début (20 %) ( Fig. 16).…”

Section: Position De La Textureunclassified

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Synthèse bibliographique : micro-texturation et microinjection de thermoplastiques

Vera

Brulez

Contraires

et al. 2017

Matériaux & Techniques

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La fonctionnalisation de surface des matériaux et notamment des polymères fait l'objet de recherches intenses dans de nombreux secteurs tels que l'industrie du biomédical ou du transport afin de conférer aux pièces des propriétés spécifiques comme l'antibuée, la réduction du frottement ou le dégivrage… Dans le cas d'une production en grande série de pièces polymères fonctionnalisées, il est préférable, pour des questions de coûts, de générer des textures, au moyen d'une technique de reproduction d'empreinte comme l'injection plastique. Toutefois les fonctions requises nécessitent parfois la reproduction de dimensions microniques voire submicroniques poussant à ses limites la maîtrise du procédé conventionnel, avec les caractéristiques de l'injection de micro-pièces, mais aussi des spécificités propres à la micro-texturation. L'objet de cette revue bibliographique est de couvrir le large spectre des problèmes techniques et scientifiques associés à la micro-texturation des pièces plastiques. Les techniques d'usinage de ces micro-motifs sur les outillages et le rôle des revêtements est particulièrement décrit ainsi que le besoin de mettre en œuvre des approches spécifiques de caractérisation topographique des textures. L'influence des paramètres du procédé d'injection est aussi discutée, soulignant la nécessité d'appréhender la micro-texturation des pièces plastiques avec une nouvelle grille de lecture de la microinjection.

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“…It is proven that it provides enhanced optical functionalities by reducing the birefringence and increasing the transmission efficiency, which are both correlated to the part internal stresses distribution. Birefringence effect is an optical property, which causes preferential light multiple refractions within the optics [9,10,11]. At the same time, the light transmission measures the effective spectral and power transmittance of the optics, i.e., a combined result of the material absorption of specific wavelengths, reflection, and surface loss.…”

Section: Introductionmentioning

confidence: 99%

Manufacturing Signatures of Injection Molding and Injection Compression Molding for Micro-Structured Polymer Fresnel Lens Production

et al. 2018

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Injection compression molding (ICM) provides enhanced optical performances of molded polymer optics in terms of birefringence and transmission of light compared to Injection molding (IM). Nevertheless, ICM requires case-dedicated process optimization to ensure that the required high accuracy geometrical replication is achieved, particularly especially in the case of surface micro-features. In this study, two factorial designs of experiments (DOE) were carried out to investigate the replication capability of IM and ICM on a micro structured Fresnel lens. A laser scanning confocal microscope was employed for the quality control of the optical components. Thus, a detailed uncertainty budget was established for the dimensional measurements of the replicated Fresnel lenses, considering specifically peak-to-valley (PV) step height and the pitch of the grooves. Additional monitoring of injection pressure allowed for the definition of a manufacturing signature, namely, the process fingerprint for the evaluation of the replication fidelity under different process conditions. Moreover, considerations on the warpage of parts were related to a manufacturing signature of the molding processes. At last, the global part mass average and standard deviation were measured to correlate local geometrical replication performances with global part quality trends.

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Polymer structure and properties in micro- and nanomolding process

Cited by 26 publications

References 14 publications

Experimental investigation of the rheological behaviors of polypropylene in a capillary flow

Experimental investigation of the rheological behaviors of polypropylene in a capillary flow

Synthèse bibliographique : micro-texturation et microinjection de thermoplastiques

Manufacturing Signatures of Injection Molding and Injection Compression Molding for Micro-Structured Polymer Fresnel Lens Production

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