Effect of blend ratio of h-LLDPE and LDPE on tear properties of blown films / K. Mezghani in INTERNATIONAL POLYMER PROCESSING, Vol. XXVII, N° 3 (07/2012)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXVII, N° 3 (07/2012) . - p. 392-398 Titre : Effect of blend ratio of h-LLDPE and LDPE on tear properties of blown films Type de document : texte imprimé Auteurs : K. Mezghani, Auteur ; S. Furquan, Auteur ; S. H. Tabatabaei, Auteur ; Abdellah Ajji, Auteur Année de publication : 2012 Article en page(s) : p. 392-398 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Alliages polymères Déchirure (mécanique) Films plastiques Matières plastiques -- Moulage par soufflage Polyéthylène basse densité Polyéthylène basse densité linéaire Index. décimale : 668.4 Plastiques, vinyles Résumé : In the present study, blown films of h-LLDPE, LDPE, and their blends were produced using a twin screw extruder. The tear properties of all films were determined in the machine direction (MD) and the transverse direction (TD). On one hand, similar values of the MD tear-resistance for the two virgin polymers, h-LLDPE and LDPE, were measured to be 100 and 120 kN/m, respectively. On the other hand, the TD tear-resistance value of h-LLDPE was 180 kN/m, four times higher than that of LDPE, 45 kN/m. It was observed that small additions of LDPE (5 to 20 wt.%) to h-LLDPE produced blends with better TD tear-resistance films, 400 kN/m. The main reason for this large increase in tear-resistance was attributed to the morphological changes induced by the addition of the LDPE polymer, as shown by SEM, FTIR, and birefringence techniques. DOI : 10.3139/217.2575 En ligne : https://drive.google.com/file/d/1km2DyzdXrFH3k6gKeOEgrvsq7BwUy_AH/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=15586 [article]

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Effect of random and block copolypropylenes on structure and properties of uniaxially and biaxially oriented PP films / S. H. Tabatabaei in INTERNATIONAL POLYMER PROCESSING, Vol. XXVI, N° 1 (03/2011)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXVI, N° 1 (03/2011) . - p. 82-90 Titre : Effect of random and block copolypropylenes on structure and properties of uniaxially and biaxially oriented PP films Type de document : texte imprimé Auteurs : S. H. Tabatabaei, Auteur ; Abdellah Ajji, Auteur ; H. Ghasemi, Auteur Année de publication : 2011 Article en page(s) : p. 82-90 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Analyse thermique Copolymères séquencés Films plastiques -- Propriétés mécaniques Microscopie en lumière polarisée Polypropylène Rhéologie Index. décimale : 668.9 Polymères Résumé : Cast films of two linear polypropylenes (PP) having different molecular weights and their blends with 5, 20, and 40 wt.% random and block copolymers were prepared. The produced cast films were uniaxially and biaxially hot drawn at T = 155ºC using a biaxial stretcher and the changes in structure and morphology were examined and related to barrier, mechanical, haze, and tear properties. The crystallinity and crystal size distribution of the films were studied using differential scanning calorimetry (DSC). The uniaxial drawing generated a highly oriented fibrillar structure, resulting in an increase in the melting point of the films. A significant effect of the random copolymer on the size of crystallites was found using DSC, which was also confirmed from polarized optical microscopy (POM). Compared to the neat homopolymers, finer and numerous spherulites were observed for the blends. During drawing, the applied loads in the machine and transverse directions (MD and TD, respectively) were recorded and related to breaking up and tilting of the crystal lamellae. Adding the random copolymer appreciably decreased the haze of the films and hence drastically improved the clarity. Tensile properties and tear resistance of the cast films in MD and TD were evaluated. The addition of the random copolymer slightly reduced the Young modulus and tensile strength, but increased the elongation at break. A slight increase in the oxygen transmission rate (OTR) of the biaxially drawn films were observed by adding the copolymer. DOI : 10.3139/217.2404 En ligne : https://drive.google.com/file/d/1Wu4KRz4nPjaAKjV4g9qq6NTTQtVcnsce/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=11053 [article]

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Effect of uniaxial stretching on molecular orientation, crystallinity and oxygen permeability of ethylene vinyl alcohol / L. Wang in INTERNATIONAL POLYMER PROCESSING, Vol. 36, N° 3 (2021)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. 36, N° 3 (2021) . - p. 314-321 Titre : Effect of uniaxial stretching on molecular orientation, crystallinity and oxygen permeability of ethylene vinyl alcohol Type de document : texte imprimé Auteurs : L. Wang, Auteur ; E. Jalali Dil, Auteur ; Abdellah Ajji, Auteur Année de publication : 2021 Article en page(s) : p. 314-321 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Analyse thermique Copolymère éthylène alcool de vinyle C'est aujourd'hui le matériau le plus utilisé dans l'emballage rigide alimentaire. Il peut être utilisé avec des matériaux de structure comme le polyéthylène, polypropylène ou polystyrène. Ce copolymère présente une excellente imperméabilité à l'oxygène, au gaz carbonique et aux arômes, à condition de protéger de l'influence de l'humidité qui fait chuter fortement ses performances. Pour palier cet inconvénient, il est souvent pris en sandwich dans des structures multicouches à base de polyoléfines PE ou PP peu sensibles à l'humidité. Il est utilisé pour les emballages de compotes, jus de fruits, fromages, sauces, crèmes et yaourts, mayonnaise, sauce tomate... Diffraction des rayons X à grand angle Etirement (mécanique) Films plastiques Orientation moléculaire (matériaux) Oxygène Perméabilité Structures multicouches Index. décimale : 668.4 Plastiques, vinyles Résumé : This work studies the effects of uniaxial stretching on molecular orientation, crystallinity, crystallography and oxygen permeability of high barrier multilayer films based on EVOH barrier layer. Film samples were prepared using two different blow-up ratios (BUR) of 1 and 3. Uniaxial stretching was applied at 100°C using a tensile machine equipped with an environmental chamber. Fourier transform infrared (FTIR) spectroscopy was used to examine the molecular orientation in the EVOH layer before and after stretching and confirmed a considerable increase in the molecular orientation in the EVOH layer. Dynamic scanning calorimetry (DSC) and wide-angle X-ray diffraction (XRD) results point to the perfection of EVOH crystal structure by applying uniaxial stretching at high temperatures. Oxygen permeability results showed a considerable 25% decrease after stretching of the sample with lower BUR while a significant 80% reduction in oxygen permeability was observed for the sample prepared at higher BUR. The mechanism involved in increasing oxygen permeability due to the uniaxial stretching at high temperature is discussed in detail. Note de contenu : EXPERIMENTAL : Materials - Film and sheet preparation - Uniaxial stretching - Scanning electron microscopy (sem) - Oxygen transmission - Differential scanning calorimetry (DSC) - Wide angle X-ray diffraction (WAXD) - Orientation index RESULTS AND DISCUSSION : Effect of stretching on layer thicknesses in the multilayer films - Effect of uniaxial stretching on molecular orientation - Effect of stretching on EVOH crystallinity and crystallography - Effect of uniaxial stretching on oxygen permeability of EVOH - Table 1 : Thickness of the layers in multilayer film samples measured from SEM image analysis - Table 2 : Calculated orientation indices of the film samples - Table 3 : Summary of DSC results for film samples before and after stretching DOI : https://doi.org/10.1515/ipp-2020-4062 En ligne : https://drive.google.com/file/d/1aV48yWOxkqVWcsGUygndhOcYux8ywd9r/view?usp=shari [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36373 [article]

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Enhancement of heat seal properties of polypropylene films by elastomer incorporation / R. Boutrouka in INTERNATIONAL POLYMER PROCESSING, Vol. XXXIII, N° 3 (07/2018)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXIII, N° 3 (07/2018) . - p. 322-326 Titre : Enhancement of heat seal properties of polypropylene films by elastomer incorporation Type de document : texte imprimé Auteurs : R. Boutrouka, Auteur ; S. H. Tabatabaei, Auteur ; Abdellah Ajji, Auteur Année de publication : 2018 Article en page(s) : p. 322-326 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Analyse thermique Copolymères Elastomères Films plastiques Matières plastiques -- Extrusion Matières plastiques -- Soudage Polypropylène Index. décimale : 668.4 Plastiques, vinyles Résumé : Seal strength at high and low temperatures as well as the width of the heat sealing temperature range are important properties in packaging industry. In addition, for sterilisable and retort applications, having those properties at elevated temperatures is crucial. Polypropylenes (PP) are usually used for these applications, however, the sealing temperatures are too high and the temperature range for the seal process is narrow, thus blending with a PP elastomer copolymer can be an alternative. In this study, hot-tack and heat seal properties were determined for a homo-polypropylene, a random co-polypropylene and an elastomer co-polypropylene based films and their blends. It is found that the seal initiation temperature (for hot tack and heat seal) is governed by the melting temperature and crystallinity and the increase of the elastomer content in the blends leads to a decrease of the seal initiation temperature. It is also shown that the sealing force depends on the ease of chains diffusion across the sealing interface. Finally, it was found that the strength of the heat sealing increases by recrystallization in the sealing interface after cooling. Note de contenu : - EXPERIMENTAL : Materials - Films co-extrusion - Thermal analysis - Heat seal testing - RESULTS AND DISCUSSION : Hot-tack DOI : 10.3139/217.3523 En ligne : https://drive.google.com/file/d/1goIWee-_8-72Jgs3Xvtxy62g1OyWcYg3/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=30800 [article]

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Investigation on the structure and properties of different PE blown films / S. Fatahi in INTERNATIONAL POLYMER PROCESSING, Vol. XXII, N° 4 (09/2007)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXII, N° 4 (09/2007) . - p. 334-345 Titre : Investigation on the structure and properties of different PE blown films Type de document : texte imprimé Auteurs : S. Fatahi, Auteur ; P. G. Lafleur, Auteur ; Abdellah Ajji, Auteur Année de publication : 2007 Article en page(s) : p. 334-345 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Molecular orientation and structure development during film blowing have a major effect on mechanical and physical properties of polyethylene films. In this work the structures and morphology of three different polyethylene blown films; linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), and high density polyethylene (HDPE) were studied. A series of blown films were produced at different process conditions. The orientation of lamellae and lamellar stacks and the morphology of the films were characterized by SEM, AFM and X-ray diffraction. SEM images of the film plane surface MT (Machine-Transverse) and cross section slices in TN (Transverse-Normal) and MN (Machine-Normal) planes were made and compared with AFM images. It was observed that the surface morphology reflects a continuation of the bulk morphology for the cases studied. Changes in the blown film process parameters, such as take up ratio (TUR), blow up ratio (BUR) and frost line height (FLH) have an effect on structural parameters, crystallinity and mechanical properties. DOI : 10.3139/217.0009 En ligne : https://drive.google.com/file/d/1F3-FJ8mom1ZKHlc_oiVsDwZ_FO0AYJpC/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2696 [article]

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Polypropylene-clay nanocomposites fibers structure and performance / Abdellah Ajji in INTERNATIONAL POLYMER PROCESSING, Vol. XXII, N° 4 (09/2007)  

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Sealibility and seal characteristics of PE/EVA and PLA/PCL blends / Z. Najarzadeh in INTERNATIONAL POLYMER PROCESSING, Vol. XXIX, N° 1 (03/2014)  

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Structure, mechanical and barrier properties of uniaxially stretched multilayer nylon/clay nanocomposites / F. Sadeghi in INTERNATIONAL POLYMER PROCESSING, Vol. XXVII, N° 5 (11/2012)  

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Tailoring heat-seal properties of biodegradable polymers through melt blending / R. Y. Tabasi in INTERNATIONAL POLYMER PROCESSING, Vol. XXXII, N° 5 (11/2017)  

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