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Challenges to the formation of nano-cells in foaming processes / Z. Zhu in INTERNATIONAL POLYMER PROCESSING, Vol. XXIII, N° 3 (07/2008)
[article]
Titre : Challenges to the formation of nano-cells in foaming processes Type de document : texte imprimé Auteurs : Z. Zhu, Auteur ; C. B. Park, Auteur ; J. H. Zong, Auteur Année de publication : 2008 Article en page(s) : p. 270-276 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : This paper uses a finite element analysis to investigate the morphological changes of nano-cells in a polystyrene (PS)–CO2 foaming system. The system was composed of a finite polymer melt with a central cell and eight surrounding cells. The computational domain was discretized using linear triangular elements. The growth and shrinkage of nano-sized cells were tracked using the moving mesh method. The effects of the initial bulk gas concentration, cell size, intercellular distance, and system temperature on cell ripening were examined. The results show that smaller nano-sized cell(s) are doomed to collapse very quickly once they have interacted with larger cell(s), making it difficult to survive. Efforts were made to improve the general understanding of the challenges posed to the formation of nano-cells in foaming processes. DOI : 10.3139/217.2050 En ligne : https://drive.google.com/file/d/1jv3RfhOvwt1VfZE9uUl9fPVZKQjPyI_q/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2627
in INTERNATIONAL POLYMER PROCESSING > Vol. XXIII, N° 3 (07/2008) . - p. 270-276[article]Réservation
Réserver ce documentA comparison of CO2 and N2 foaming behaviors of PP in a visualization system / Q.-P. Guo in INTERNATIONAL POLYMER PROCESSING, Vol. XXXV, N° 5 (11/2020)
[article]
Titre : A comparison of CO2 and N2 foaming behaviors of PP in a visualization system Type de document : texte imprimé Auteurs : Q.-P. Guo, Auteur ; J. Wang, Auteur ; C. B. Park, Auteur Année de publication : 2020 Article en page(s) : p. 503-517 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Azote
Dioxyde de carbone
Etudes comparatives
Matériaux -- Allègement
Matières plastiques dans les automobiles
Mousses plastiques
PolypropylèneIndex. décimale : 668.4 Plastiques, vinyles Résumé : Understanding of polypropylene (PP) foaming is critically important to reduce the weight of automotive parts. In this study, we used a batch foaming simulation system with visualization cell, to observe the foaming behaviors of PP that is blown with CO2 and N2 under various experimental conditions. We found that the nucleating agent content, initial temperature, pressure (i. e., gas content), and pressure drop rate during foaming have a significant effect on cell nucleation and cell growth. The cell density and the void fraction of PP foamed with CO2 and N2, respectively, were separately observed and compared. It was found that under the same experimental conditions, the maximum cell density of PP foamed with CO2 was higher than that of PP foamed with N2. However, the maximum cell density of PP foamed with CO2 was determined to be lower than that of PP foamed with N2, when the same gas mole numbers were employed. Based on the experimental results, optimum foaming conditions and effective processing strategies for PP-CO2 system are suggested. Note de contenu : - MATERIALS AND METHODS : Materials - Foaming experiment
- RESULTS AND DISCUSSION : Foaming with CO2 - Foaming with N2 - Comparison of PP foaming with CO2 and N2DOI : https://doi.org/10.3139/217.3993 En ligne : https://drive.google.com/file/d/1atcaNF_7wbnVwlhGJt2mnzwBGl_bsSx0/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=35072
in INTERNATIONAL POLYMER PROCESSING > Vol. XXXV, N° 5 (11/2020) . - p. 503-517[article]Réservation
Réserver ce documentIn situ visualization for control of nano-fibrillation based on spunbond processing using a polypropylene-polyethylene terephthalate system / A. N. Md. Shahin in INTERNATIONAL POLYMER PROCESSING, Vol. 36, N° 3 (2021)
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Titre : In situ visualization for control of nano-fibrillation based on spunbond processing using a polypropylene-polyethylene terephthalate system Type de document : texte imprimé Auteurs : A. N. Md. Shahin, Auteur ; V. Shaayegan, Auteur ; P. C. Lee, Auteur ; C. B. Park, Auteur Année de publication : 2021 Article en page(s) : p. 332-344 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Fibres textiles synthétiques
Fibrillation
Filature
Liage
Microfibres
Nanofibres
Nanotechnologie
Polyéthylène téréphtalate
Polypropylène
RhéologieIndex. décimale : 668.4 Plastiques, vinyles Résumé : In situ generation of polyethylene terephthalate (PET) nanofibrils in polypropylene (PP) microfibers via fiber spinning in a spunbond process was studied in this work. The effects of polymer flow rate and air speed in the drafter on the formation of PET fibrils were investigated using a pilot scale machine. An in-situ visualization technique was applied to examine the fiber evolution events and stretch profile at die exit. A scanning electron microscope was used to analyze and investigate the morphology of the dispersed domain. The PET dispersed phase was fibrillated within the PP matrix such that a nonofibrillated composite containing fibrils with an average size around 100 nm was obtained. It was found that the final fibril size directly depends on the degree of die swell, the air speed and the polymer flow rate. It was also found that the in situ observed size of the micro-scale PP/PET fibers was well correlated to the size of the nano-scale PET fibers formed in the PP matrix. The visualization results revealed that a smaller fibril diameter was obtainable by increasing the stretching on the spin line and/or decreasing the die swell. Note de contenu : - EXPERIMENTAL : Materials - Rheological measurements - Fiber spinning setup - Scanning electron microscopy (SEM) and optical microscope - In situ visualization of the die swell phenomenon
- RESULTS AND DISCUSSION : In situ visualization of macroscopic fibrillation of PP/PET fibers at die exit - Investigation of the collected PP/PET microfibrils - Investigation of pet nanofibrils formed within the PP/PET microfibril - Correlation between the PP/PET microfibril size and the pet nanofibril sizeDOI : https://doi.org/10.1515/ipp-2020-4072 En ligne : https://drive.google.com/file/d/1PQEzJCBqaEWmWWTzTat875yHMb-Pl-W2/view?usp=shari [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36375
in INTERNATIONAL POLYMER PROCESSING > Vol. 36, N° 3 (2021) . - p. 332-344[article]Réservation
Réserver ce documentOptimization of dispersion of nanosilica particles in a PP matrix and their effect on foaming / S.-H. Lee in INTERNATIONAL POLYMER PROCESSING, Vol. XXVI, N° 4 (09/2011)
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Titre : Optimization of dispersion of nanosilica particles in a PP matrix and their effect on foaming Type de document : texte imprimé Auteurs : S.-H. Lee, Auteur ; Y. Zhang, Auteur ; Marianna Kontopoulou, Auteur ; C. B. Park, Auteur ; A. Wong, Auteur ; W. Zhai, Auteur Année de publication : 2011 Article en page(s) : p. 388-398 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Cisaillement (mécanique)
Dispersions et suspensions
Extrudeuse bi-vis
Matériaux hybrides
Microscopie électronique en transmission
Mousses plastiques -- Extrusion
Nanoparticules
Polypropylène
SiliceLa silice est la forme naturelle du dioxyde de silicium (SiO2) qui entre dans la composition de nombreux minéraux.
La silice existe à l'état libre sous différentes formes cristallines ou amorphes et à l'état combiné dans les silicates, les groupes SiO2 étant alors liés à d'autres atomes (Al : Aluminium, Fe : Fer, Mg : Magnésium, Ca : Calcium, Na : Sodium, K : Potassium...).
Les silicates sont les constituants principaux du manteau et de l'écorce terrestre. La silice libre est également très abondante dans la nature, sous forme de quartz, de calcédoine et de terre de diatomée. La silice représente 60,6 % de la masse de la croûte terrestre continentale.Index. décimale : 668.4 Plastiques, vinyles Résumé : Nanocomposites based on isotactic polypropylene (PP) and nanosilica (SiO2) were prepared using a co-rotating twinscrew extruder (TSE). The effect of operating variables, such as screw speed and screw configuration on the dispersion of nanosilica in the polymer matrix has been studied, using TEM imaging. High shear stress, sufficient residence time, and high fill ratio in the melting section of the screw were the most important factors in achieving good nanosilica dispersion. Furthermore, the effects of filler loading and amount of a maleated polypropylene (PP-g-MA) compatibilizer on the degree of SiO2 dispersion were investigated. The foaming performance of the composites was evaluated using a batch foaming simulation system, and an extrusion foaming setup that employed respectively N2 and CO2 blowing agents. Well-dispersed surface-modified hydrophobic SiO2 particles acted as effective nucleating agents for foaming, when used at loadings below 1 phr. DOI : 10.3139/217.2403 En ligne : https://drive.google.com/file/d/1byBjy0SU9dR5h39bPLc5y_uCkxKcS6Ci/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=12440
in INTERNATIONAL POLYMER PROCESSING > Vol. XXVI, N° 4 (09/2011) . - p. 388-398[article]Réservation
Réserver ce documentSimha-Somcynsky equation of state modeling of the PVT behavior of PP/clay-nanocomposite/CO2 mixtures / M. M. Hasan in INTERNATIONAL POLYMER PROCESSING, Vol. XXIX, N° 4 (08/2014)
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Titre : Simha-Somcynsky equation of state modeling of the PVT behavior of PP/clay-nanocomposite/CO2 mixtures Type de document : texte imprimé Auteurs : M. M. Hasan, Auteur ; C. B. Park, Auteur Année de publication : 2014 Article en page(s) : p. 430-439 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Argile
Matériaux hybrides
Mesure de pression-volume-température
Modèles mathématiques
Mousses plastiques
Nanoparticules
PolypropylèneIndex. décimale : 668.4 Plastiques, vinyles Résumé : The Pressure-Volume-Temperature (PVT) property of polymer nanocomposite (PNC)/gas solutions is an important fundamental property in the foaming of PNC. However, accurate data have not yet been reported. We examined the PVT behaviors of polypropylene (PP) and PP/organoclay polymer nanocomposite (PP-PNC) by monitoring the swelling changes of the polymer melt in supercritical carbon dioxide (scCO2). A model was adopted that describes the PVT behaviors of PP-PNC with and without dissolved gas. Based on the model, a PNC consists of two sections: a hard section (a nanoparticle surrounded by solidified polymer) and a soft section (neat polymer). It was observed that an infusion of nanoparticles decreased the swelling. It seems that the hard section had a minimal free volume in which to dissolve the blowing agents, and that the number of hard sections increased with the infusion of nanoparticles. As a result, the total gas absorption capacity of the system decreased, and consequently, the swelling also decreased. Note de contenu : - THEORETICAL BACKGROUND : Modeling of organoclay nanocomposites - Swelling determination of the PNC system
- EXPERIMENTATION : Materials - Experimental setup - Methodology - Experimental verification
- RESULTS AND DISCUSSION : PVT behavior of PP and PP nanocomposites - Swelling behavior of PP and the PP nanocomposites - Comparison of all three approachesDOI : 10.3139/217.2815 En ligne : https://drive.google.com/file/d/1q238lUO4VfL8_PTAWmTfySU2yaGcE473/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=21821
in INTERNATIONAL POLYMER PROCESSING > Vol. XXIX, N° 4 (08/2014) . - p. 430-439[article]Réservation
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