Absorption coefficient measurement in laser transmission welding of thermoplastics / M. Chen in INTERNATIONAL POLYMER PROCESSING, Vol. XXX, N° 1 (03/2015)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXX, N° 1 (03/2015) . - p. 38-43 Titre : Absorption coefficient measurement in laser transmission welding of thermoplastics Type de document : texte imprimé Auteurs : M. Chen, Auteur ; G. Zak, Auteur ; Phil J. Bates, Auteur Année de publication : 2015 Article en page(s) : p. 38-43 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Absorption Composites à fibres de verre Matières plastiques -- Soudage Noir de carbone Polyamide 6 Soudage laser Index. décimale : 668.9 Polymères Résumé : Laser transmission welding involves joining of transmitting and absorbing thermoplastic polymer components. Absorption is normally controlled by addition of small amounts of carbon black (CB). In thermal modelling of the process, the laser-light absorption coefficient is an important parameter that controls the rate and distribution of heat generation in the absorbing component. This paper introduces a novel experimental method to conveniently and accurately measure the absorption coefficient in the absorbing component. In this method, a laser beam scans rapidly over the surface of the CB-filled polymer. The laser power resulting in the onset of surface melting can be obtained and used to calculate the absorption coefficient based on an analytical model presented in this paper. To validate the proposed method, the experimental results were compared with those obtained by the spectrophotometer and the power-meter methods using unreinforced and glass-fiber reinforced nylon 6. The results indicate that there is a linear relationship between the absorption coefficient and carbon black level for these two polymers. The influence of glass fibers and laser scan speed on the measurement are also discussed. Note de contenu : - BACKGROUND : Laser transmission welding - Bouguer-Lambert law - Absorption coefficient measurement - PRINCIPLE AND EXPERIMENTAL SETUP OF THE DIRECT-SCAN METHOD : Measurement principle - Test materials - Experimental setup - EXPERIMENTAL RESULTS AND ANALYSIS : Absorption coefficient vs. CB level - Test methods comparison DOI : 10.3139/217.2820 En ligne : https://drive.google.com/file/d/1EQU7GfazF9ZZ1vm3z4s6msj7J-5MA5wH/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=23416 [article]

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Polymer melt impregnation of glass roving / Phil J. Bates in INTERNATIONAL POLYMER PROCESSING, Vol. XVII, N° 4 (12/2002)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XVII, N° 4 (12/2002) . - p. 376-386 Titre : Polymer melt impregnation of glass roving : Modelling and experimental Type de document : texte imprimé Auteurs : Phil J. Bates, Auteur ; X. P. Zou, Auteur Année de publication : 2002 Article en page(s) : p. 376-386 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Much attention has been recently focussed on the melt impregnation of thermoplastic polymers as a consequence of the difficulty involved in driving viscous polymer melt into a tightly packed fiber bundle. This work studies an impregnation process consisting a series of staggered cylindrical pins in a melt pool. A numerical model for evaluating the pressure generation in the wedge region between the roving/pin, the impregnation velocity of the melt through the glass mesh, and the resulting impregnation depth along the wedge is developed using relationships for pressure build-up in foil bearings and Darcy's law. The model results are compared with experimental melt impregnation data. The model adequately predicts the effect of melt impregnation process conditions on impregnation quality. Note de contenu : - EQUIPMENT, PROCEDURE AND MATERIALS : Equipment - Materials - Impregnation assessment - MODELLING : Assumptions - Pressure generation in the wedge region - Flow through the glass mesh - Impregnation depth and melt flow - Calculation of the impregnation number - Solving the system of impregnation equations - RESULTS AND DISCUSSION : Comparison of experimental and model results - Discussion of impregnation model - Kozeny constant value - Pressure and impregnation profiles DOI : 10.3139/217.1705 En ligne : https://drive.google.com/file/d/1JQ1yT3q90BnBLmJH3Yg1Jsq-yXdrnybb/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16042 [article]

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Simulation of heat transfer in laser transmission welding / R. Prabhakaran in INTERNATIONAL POLYMER PROCESSING, Vol. XX, N° 4 (12/2005)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XX, N° 4 (12/2005) . - p. 410-416 Titre : Simulation of heat transfer in laser transmission welding Type de document : texte imprimé Auteurs : R. Prabhakaran, Auteur ; Marianna Kontopoulou, Auteur ; G. Zak, Auteur ; Phil J. Bates, Auteur ; V. Sidiropoulos, Auteur Année de publication : 2005 Article en page(s) : p. 410-416 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : A numerical simulation of the heat transfer during laser transmission welding is presented. A finite difference approach was used to solve the one-dimensional unsteady-state heat conduction problem and to investigate the effect of welding conditions on the time-dependent temperature profiles for PA 6. For the needs of the simulation, the process was divided into heating and heat redistribution periods. The absorption coefficient of the laser-transparent part was measured experimentally and that of the laser-absorbing part was fitted using experimental data. The predicted temperature profiles were combined with experimental meltdown data to estimate the heat-affected zone thickness in the welded specimens. Good agreement was found between the estimated and measured heat-affected zone thickness values. En ligne : https://drive.google.com/file/d/1EPZG66vHoA0ClrbNJZ4jBb-15CA8U5yA/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2966 [article]

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The effect of molecular parameters on the thermal behavior of recycled and virgin polyamides and their glass fiber composites / A. Mirzadeh in INTERNATIONAL POLYMER PROCESSING, Vol. XXIX, N° 1 (03/2014)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXIX, N° 1 (03/2014) . - p. 4-12 Titre : The effect of molecular parameters on the thermal behavior of recycled and virgin polyamides and their glass fiber composites Type de document : texte imprimé Auteurs : A. Mirzadeh, Auteur ; H. Ghasemi, Auteur ; Phil J. Bates, Auteur ; Musa R. Kamal, Auteur Année de publication : 2014 Article en page(s) : p. 4-12 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Composites à fibres de verre Composites à fibres de verre -- Recyclage Cristallisation Poids moléculaires Polyamide 6 Polyamide 66 Polymères -- Recyclage Produits et matériaux recyclés Structure moléculaire Index. décimale : 668.4 Plastiques, vinyles Résumé : A study was carried out to evaluate the effects of molecular weight and molecular structure on non-isothermal crystallization behavior of recycled and virgin polyamides (PA) and their corresponding glass fiber (GF) composites. Two different recycled polyamides (PA), namely post-industrial waste (PIW) and post-consumer waste (PCW) were used. The former was obtained from a fiber manufacturer and the latter was recycled from used carpets. The molecular weights of the resins were measured by intrinsic viscosity (IV) measurements and 13carbon nuclear magnetic resonance (13C-NMR). The NMR technique also provided information on PA structure, cis and trans amide conformers content and residual unreacted monomer. Non-isothermal crystallization of the resins was studied using differential scanning calorimetry (DSC). The molecular weights of recycled materials were higher than that of virgin injection molding grade PA-6. However, the crystallization rates (indicated by t1/2) of recycled resins were faster. It could be attributed to the presence of TiO2 in recycled materials. Moreover, the higher cis-amide conformer content of recycled resins suggested higher segmental mobility. On the other hand, the crystallization rate of composites based on recycled PA-6 was slower than that of composites based on the virgin PA-6. The suppression of crystallization rate was apparently due to PA-66 added during the preparation of reinforced recycled resins. This behavior was confirmed by model compounds based on PA-6/PA-66 blends. Note de contenu : - EXPERIMENTAL : Materials - Sample preparation and characterization - RESULTS AND DISCUSSION : Molecular weight measurements - Molecular parameters - Non-isothermal crystallization DOI : 10.3139/217.2775 En ligne : https://drive.google.com/file/d/1KHoV0g1ESFxZQ5ZDVRn6ufTY_hKn1AqA/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=20570 [article]

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