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Effect of pre-molding process and additive of injection molded wood/PP composites / Y. Yu in INTERNATIONAL POLYMER PROCESSING, Vol. XXIX, N° 4 (08/2014)
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Titre : Effect of pre-molding process and additive of injection molded wood/PP composites Type de document : texte imprimé Auteurs : Y. Yu, Auteur ; Q. Y. Yang, Auteur ; M. Nomura, Auteur ; H. Hamada, Auteur Année de publication : 2014 Article en page(s) : p. 440-446 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Bois
Composites à fibres -- Additifs
Composites à fibres végétales -- Moulage par injection
Composites à fibres végétales -- Propriétés mécaniques
Flexion trois points
Impact (mécanique)
Morphologie (matériaux)
Polyalphaoléfine
Polypropylène
Poudres
Traction (mécanique)Index. décimale : 668.4 Plastiques, vinyles Résumé : Injection molded composites are becoming more widespread in recent years because of their high quality and low cost. However, compared to synthetic fiber composites, it is difficult to maintain a constant fiber volume fraction and uniform distribution for natural fiber composites during the direct injection process. This is mainly because natural fibers are more easily twisted during feeding into the injection machine, owing to their rough surfaces. These feeding difficulties are particularly due to the low bulk densities of natural fibers, especially natural fillers. Additional challenges to the injection process include the concentration and, especially for natural filler reinforced composite. To address these problems, the current study investigates the mechanical properties and morphologies of polypropylene (PP) reinforced by wood powder. Two pre-molding processes, dry-blending and compounding, were compared, and the effects of an additive (crystalline polyalpha olefin (CPAO)) on the mechanical properties of the wood/PP composites were investigated. This investigation is based on tensile, three point bending, and Izod impact tests, and scanning electron microscope (SEM) observation of the fracture surfaces. Results indicated that the composites molded through compounding exhibited better mechanical properties than the samples molded through the direct dry-blending process. In addition, the tensile and bending properties of the composites produced through compounding were found to increase with the addition of CPAO content, because of improved wood powder distribution in the PP matrix. Note de contenu : - EXPERIMENTAL : Materials - Dry-blending and compounding - Injection molding - Tensile test - Three point bending test - Izod impact test - Etching process - Scanning electron microscopy (SEM)
- EXPERIMENTAL RESULTS AND DISCUSSION : Particle size distribution of wood powder - Effect of pre-molding process (dry-blending and compounding) - Effect of CPAO contentDOI : 10.3139/217.2826 En ligne : https://drive.google.com/file/d/1P3Hu1gTgnzQJFtF2RLYJWGwP7EzDsJci/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=21822
in INTERNATIONAL POLYMER PROCESSING > Vol. XXIX, N° 4 (08/2014) . - p. 440-446[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 16454 - Périodique Bibliothèque principale Documentaires Disponible Structure development in injection molding of isotactic polypropylene, its blends, compounds and dynamic vulcanizates / Y. Yu in INTERNATIONAL POLYMER PROCESSING, Vol. XVIII, N° 4 (12/2003)
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Titre : Structure development in injection molding of isotactic polypropylene, its blends, compounds and dynamic vulcanizates Type de document : texte imprimé Auteurs : Y. Yu, Auteur ; J. L. White, Auteur Année de publication : 2003 Article en page(s) : p. 388-397 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : MOLDING - We make a comparative study of structure development in injection molding of isotactic polypropylene, polypropylene blends/compounds and dynamically vulcanized polypropylene thermoplastic elastomers (TPVs) WAXS 2θ scans were used to determine crystalline forms and the distribution of relative amounts of crystalline forms through the cross-section of injection molded parts. WAXS film patterns, polarized optical light micrographs and birefringence were used to qualitatively indicate polymer chain orientation variation through the cross-section. We also used WAXS pole figures to investigate polymer crystalline orientation and filler orientation in different layers of the injection molded parts.
It was found that a low or modest orientation layer exists on the part surface. There is an intermediate highly oriented layer in the parts of isotactic polypropylene and most polypropylene blends/compounds. The interior of the parts was spherulitic and increasingly isotropic as one moved to the center. The thickness of the surface layer increases as the injection pressure decreases. The layer was not observed in parts of dynamically vulcanized polypropylene thermoplastic elastomers. This would seem to be associated with the TPVs possessing a yield stress and not exhibiting substantial fountain flow in mold filling.Note de contenu : - EXPERIMENTAL : Materials - Shear viscosity - Injection molding - Methods used to cut thin slices - Birefringence and polarized light optical photo micrographs - Wide angle X-ray diffraction 2o scans - Wide angle X-ray diffraction film patterns and pole figures
- RESULTS : Identification of crystalline modifications - WAXS film patterns - Polarized light optical micrographs - Birefringence - WAXS pole figures
- DISCUSSION : Fluide mechanics of mold filling of thermoplastics melts of PP, blends, compounds and TPVs - Energy balance and melt solidification - Formation of b-crystals in injection molded parts - Influence of oriented talc discs on PP crystallographic axis orientationDOI : 10.3139/217.1786 En ligne : https://drive.google.com/file/d/1tFoY5TWIgvIondiZMqhxu09-MWiFeEgx/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=15823
in INTERNATIONAL POLYMER PROCESSING > Vol. XVIII, N° 4 (12/2003) . - p. 388-397[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 001026 - Périodique Bibliothèque principale Documentaires Disponible Structure development in melt spinning polypropylene-EPM blends and dynamically vulcanized polyolefin TPEs / Y. Yu in INTERNATIONAL POLYMER PROCESSING, Vol. XIV, N° 2 (06/1999)
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Titre : Structure development in melt spinning polypropylene-EPM blends and dynamically vulcanized polyolefin TPEs Type de document : texte imprimé Auteurs : Y. Yu, Auteur ; J. L. White, Auteur Année de publication : 1999 Article en page(s) : p. 159-167 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Fibers and films - Polypropylene blends, both mechanical blends and a dynamically vulcanized blend, have been melt spun into fibers. Melt spinning was carried out through air and in ice water. Melt spun filaments were characterized by wide angle x-ray diffraction (WAXS), birefringence and differential scanning calorimetry (DSC) measurements. Generally, the polypropylene crystalline orientation-spinline stress relationship is the same for the homoploymer, the blends and the dynamic vulcanizate. However, the blends and the dynamic vulcanizate have much lower birefringence apparently due to a lack of orientation in the rubber phase. It was shown that the PP contribution to the birefringence for all the systems is the same at the same spinline stress. Note de contenu : - EXPERIMENTAL : Materials - Material characterization - Melt spinning procedures - Fiber characterization
- RESULTS : Spinline stresses - WAXS patterns and diffractometer scans - DSC scans and crystallinity - Crystalline orientation - Birefringence
- DISCUSSION : Spinline stress and shear viscosity - Crystallinity - Crystalline orientation - BirefringenceDOI : 10.3139/217.1535 En ligne : https://drive.google.com/file/d/1F95vZzJRMdVQ7PTFHr_2Sts26zekVJXr/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16097
in INTERNATIONAL POLYMER PROCESSING > Vol. XIV, N° 2 (06/1999) . - p. 159-167[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 001008 - Périodique Bibliothèque principale Documentaires Disponible