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Discontinuous unidirectional prepreg makes complex parts possible / John Simko in JEC COMPOSITES MAGAZINE, N° 73 (06/2012)
[article]
Titre : Discontinuous unidirectional prepreg makes complex parts possible Type de document : texte imprimé Auteurs : John Simko, Auteur Année de publication : 2012 Article en page(s) : p. 66-67 Langues : Anglais (eng) Catégories : Enduction textile
Etirement (mécanique)
Matériaux -- Imprégnation
Textiles et tissus à usages techniques -- Propriétés mécaniques
TissésIndex. décimale : 668.4 Plastiques, vinyles Résumé : Reinforcement - Pepin Associates has developed a discontinuous unidirectional preimpregnated reinforcement tape (unitape) which has the ability to stretch up to 30 % to form complex shapes. The material, called DiscoTape (subject of provisional patent), has shown promise in the formation of composite parts with complex curvatures normally precluding the use of unitape without cutting and darting. En ligne : https://drive.google.com/file/d/1IZM9iB5tBj9eXwwtbnCRnAsH4ucyFddd/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=15718
in JEC COMPOSITES MAGAZINE > N° 73 (06/2012) . - p. 66-67[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 14110 - Périodique Bibliothèque principale Documentaires Disponible Effect of cyclic stress on the structure and mechanical properties of leather / Keyong Tang in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 104, N° 4 (07-08/2020)
[article]
Titre : Effect of cyclic stress on the structure and mechanical properties of leather Type de document : texte imprimé Auteurs : Keyong Tang, Auteur ; Zhenye Tang, Auteur ; Fang Wang, Auteur ; Jie Liu, Auteur ; Cem Emre Fera, Auteur Année de publication : 2020 Article en page(s) : p. 163-169 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Caractérisation
Contraintes (mécanique)
Cuirs et peaux -- Analyse
Cuirs et peaux -- Propriétés mécaniques
Etirement (mécanique)
HystérésisL'hystérésis (ou hystérèse) et signifiant "après" ou "plus tard", est la propriété d'un système qui tend à demeurer dans un certain état quand la cause extérieure qui a produit le changement d'état a cessé.
MicroscopieIndex. décimale : 675 Technologie du cuir et de la fourrure Résumé : Leathers are collagen-based biomaterials with very good viscoelasticity. In leather making, leather has to endure many different kinds of forces, especially cyclic stress. The response of leather to these stresses not only determines the properties of the leather, but also affects the mechanical behaviours of leather. Cycle stress is very common during the post-tanning process and use of leather. In this paper, two types of cyclic stretching were employed to study the mechanical response of leather to cyclic stress. The general patterns of different energy changes were studied. Both large hysteresis loop and residual strain were found for the leather after the first cycle of cyclic stretching. Loading energy, hysteresis and peak stress decrease with increasing the stretching cycles, while the unloading energy nearly keeps stable. 'Rest' has an important effect on the recovery of residual strain of leather. Cyclic stretching improves the softness of leather by unfolding the sticky collagen fibres. There is a linear relationship between the loading energy and the hysteresis of the leather, regardless of the stretching modes. Note de contenu : - EXPERIMENTAL DETAILS : Materials and procedures - Microscopy characterisation
- RESULTS AND DISCUSSION : Cyclic strain-stress behaviour - Effect of 'rest' after cyclic stretching on mechanical response of leatherEn ligne : https://drive.google.com/file/d/1eiO3wT3o3u-BnZPtYESMyr2Kz4x6o8dX/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34329
in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 104, N° 4 (07-08/2020) . - p. 163-169[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 21881 - Périodique Bibliothèque principale Documentaires Disponible Effect of plug temperature on the strain and thickness distribution of components made by plug assist thermoforming / D. Marathe in INTERNATIONAL POLYMER PROCESSING, Vol. XXXI, N° 2 (05/2016)
[article]
Titre : Effect of plug temperature on the strain and thickness distribution of components made by plug assist thermoforming Type de document : texte imprimé Auteurs : D. Marathe, Auteur ; D. Rokade, Auteur ; L. Busher Azad, Auteur ; K. Jadhav, Auteur ; S. Mahajan, Auteur ; Z. Ahmad, Auteur ; S. Gupta, Auteur ; S. Kulkarni, Auteur ; V. Juvekar, Auteur ; Ashish Lele, Auteur Année de publication : 2016 Article en page(s) : p. 166-178 Langues : Anglais (eng) Catégories : Etirement (mécanique)
Matières plastiques -- Thermoformage
Polymères -- Effets de la température
Polystyrène choc
RhéologieIndex. décimale : 668.4 Plastiques, vinyles Résumé : Plug temperature is a key parameter affecting the thickness distribution of thermoplastic components made by plug assist thermoforming. For a specified pair of plug and plastic sheet, the variation in plug temperature can alter the coefficient of friction (COF) between the pair. We show here how the temperature dependence of COF influences the nature and extent of biaxial stretching of the sheet and consequently the thickness distribution of the thermoformed component. In the present study, high impact polystyrene (HIPS) sheets were thermoformed into axisymmetric cups using a plug-assist process in which the aluminum plug temperature (Tplug) was varied from ambient to above the glass transition temperature of HIPS (∼100 °C). Biaxial strain maps on the surfaces of the formed cups were measured and quantified using Grid Strain Analysis (GSA). Thickness distributions of the cups were also measured. Temperature dependent COF between HIPS and aluminum was determined independently using a rotational rheometer. The measured COF was low for T < 100 °C, whereas it increased appreciably at and above 100 °C. We conclude that when Tplug < 100 °C the HIPS sheet slips on the plug during forming, and this results in biaxial stretching of the base and walls of the formed cup. In contrast for Tplug > 100 °C, a significant reduction in the magnitude of slip is expected. Here the sheet is gripped at the clamp and by the plug during forming which causes reduced biaxial stretching of the base and increased uniaxial stretching of the walls of the cup. Simulations of plug-assist thermoforming using a temperature dependent COF showed qualitative agreement with the GSA data thereby supporting our inferences. DOI : 10.3139/217.3060 Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=26171
in INTERNATIONAL POLYMER PROCESSING > Vol. XXXI, N° 2 (05/2016) . - p. 166-178[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 17979 - Périodique Bibliothèque principale Documentaires Disponible 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]
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 vinyleC'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 Ã grand angle
Etirement (mécanique)
Films plastiques
Orientation moléculaire (matériaux)
Oxygène
Perméabilité
Structures multicouchesIndex. 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 stretchingDOI : 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 : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36373
in INTERNATIONAL POLYMER PROCESSING > Vol. 36, N° 3 (2021) . - p. 314-321[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 23733 - Périodique Bibliothèque principale Documentaires Disponible Mechanical microscopic analysis in the process of stretching cowskin collagen / Zhong Anhua in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 107, N° 1 (01-02/2023)
[article]
Titre : Mechanical microscopic analysis in the process of stretching cowskin collagen Type de document : texte imprimé Auteurs : Zhong Anhua, Auteur ; Huang Zhuo, Auteur ; Fang Songchun, Auteur ; Zhou Meng, Auteur Année de publication : 2023 Article en page(s) : p. 16-18 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Collagène -- Analyse
Cuirs et peaux -- Propriétés mécaniques
Cuirs et peaux de bovins
Etirement (mécanique)
Microscopie
Traction (mécanique)Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The tensile properties of cowskin leather are expressed in terms of its important mechanical properties. Variation in the collagen of cowhide is the microscopic cause of the tensile properties of cowhide. The aim of this study was to perform molecular dynamics simulations for the collagen stretching process of clothing cowhide at the rate of 0.01nm/ps, on lengths of 10nm. The changes in the RMSD (root square mean deviation of atomic position), SASA (solvent accessible surface), potential energy, and hydrogen bonding of collagen throughout the stretching process were obtained. The RMSD of the collagen fluctuated during the stretching process and tended to equilibrate. SASA increased with increasing voltage and reached a critical condition at 900 ps. In the molecular unwinding and uncoiling stage, the potential energy remained constant and it increased rapidly in the stage of stretching backbone. The numbers of hydrogen bonds within the collagen gradually decreased but increased between collagen and the aqueous solvent, with both hydrogen bonds reaching a turning point at 900ps. Note de contenu : - Research theory
- Experimental procedures
- Results and discussion : RMSD analysis - SASA analysis - Potential energy analysis - Hydrogen bonds analysisEn ligne : https://drive.google.com/file/d/1_x0hOgHg-Dpk_o9VVc7w3D9eLZfokaEg/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=38868
in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 107, N° 1 (01-02/2023) . - p. 16-18[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 23893 - Périodique Bibliothèque principale Documentaires Disponible A novel non-planar transverse stretching process for micro-porous PTFE membranes and resulting characteristics / Y.-H. Chang in INTERNATIONAL POLYMER PROCESSING, Vol. XXXIII, N° 1 (03/2018)
PermalinkResearch on experimental exploration and identification positioning algorithm for the optimal stretching point of leather in the toggling process / Huan Yuan in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 107, N° 5 (09-10/2023)
PermalinkSpecialty fibers in sports and leisure textiles / R. Senthil Kumar in CHEMICAL FIBERS INTERNATIONAL, Vol. 62, N° 2 (05/2012)
PermalinkStretching and stress-relaxation of leather / Albert M. Manich in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 90, N° 3 (05-06/2006)
PermalinkPermalinkStructure and properties of microporous modified PET fiber / Wang Caihua in CHEMICAL FIBERS INTERNATIONAL, Vol. 62, N° 2 (05/2012)
PermalinkStructure and properties of microporous modified PET fiber / Wang Caihua in CHEMICAL FIBERS INTERNATIONAL, (10/2012)
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