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Ajouter le résultat dans votre panierMixing homologous high viscosity ratio polymer blends in converging flow / M. Meller in INTERNATIONAL POLYMER PROCESSING, Vol. XIV, N° 3 (09/1999)
Titre : Mixing homologous high viscosity ratio polymer blends in converging flow Type de document : texte imprimé Auteurs : M. Meller, Auteur ; André Luciani, Auteur ; Jan-Anders E. Manson, Auteur Année de publication : 1999 Article en page(s) : p. 221-227 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Several studies have shown that deformation and breakup of dispersed droplets is easier in extensional than in shear flow field and this is particularly true for systems with high viscosity ratios. The simplest way to generate a significant extensional flow field in compounding equipment is to use converging flow conditions. In this work, the mixing efficiency of converging flow has been investigated as a function of the entry profile and the flow rate by using a capillary rheometer equipped with dies of different geometries. The material used for this study was a bimodal polyethylene presenting inhomogeneities due to the high viscosity ratio between the low and high molecular weight fractions. The results indicated that the mixing performance depended strongly on the die geometry and flow rate. A critical flow rate was observed for each particular entry profile at which the highest efficiency was observed. This critical flow rate was found to correspond to the onset of melt flow instabilities. Note de contenu : - EXPERIMENTAL PART : Rheological characterization - Converging flow experiments - Characterization- Materials - procedure
- RESULTS AND DISCUSSION : Model bimodal blends - Converging flowDOI : 10.3139/217.1549 En ligne : https://drive.google.com/file/d/1jn5TpIji956nOtujlJtIeSNxNMHYKgEB/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16132
in INTERNATIONAL POLYMER PROCESSING > Vol. XIV, N° 3 (09/1999) . - p. 221-227[article]Réservation
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Titre : The effect of miscibility on rheological and mechanical properties of PCL/SAN blends Type de document : texte imprimé Auteurs : P. Saha, Auteur ; L. Keyzlarová, Auteur Année de publication : 1999 Article en page(s) : p. 228-233 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Earlier, poly(ε-caprolactone) (PCL) and poly(styrene-co-acrylonitrile) (SAN) were found to be miscible on molecular level at 8 up to 28 wt. % of acrylonitrile (AN) in SAN copolymer [1]. The combination of PCL and different copolymers of SAN thus offers an opportunity to investigate the effect of miscibility on some key properties of the blends, e.g. rheological or mechanical. In this paper blends containing SAN with 25 wt. % of AN (miscible SAN-25) and 35 wt. % of AN (immiscible SAN-35) were used for this purpose.
Blends of PCL with various contents of SANs up to 40wt.% were prepared by melt mixing in a Brabender laboratory mixer. The miscibility of the mixed PCL/SAN blends was investigated by differential scanning calorimetry (DSC). The blends rheological characteristics were determined on a Rheoflixer capillary rheometer at various temperatures. Rabinowitsch and Bagley corrections and the power-law relation were used. The extrudates were observed under a scanning electron microscope. In addition, mechanical testing was performed on a tensile testing machine.
It was found that blends of PCL with a minor amount of miscible SAN-25 provide a better balance of rheological and mechanical properties than those of pure PCL. The immiscible blend shows properties inferior to the miscible one. Immiscible SAN-35 increases viscosity, shear thinning and extrudate swell of PCL more than the miscible type. In contrast to the miscible blends containing SAN-25, which were without any form of unstable flow at shear rates of 10 to 10000s-1, melt fracture occurs in the immiscible blends with SAN-35. Positive synergism in tensile strength and elongation at break can be seen for 90/10 PCL/SAN-25 blend processed at 130°C. The addition up to 30wt.% of SAN-25 miscible with PCL increases elongation at break.DOI : 10.3139/217.1552 En ligne : https://drive.google.com/file/d/1VNdJLxGZmIitKBDejvTQQq28aNa0uNPW/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16133
in INTERNATIONAL POLYMER PROCESSING > Vol. XIV, N° 3 (09/1999) . - p. 228-233[article]Réservation
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Titre : Effect of twin-screw extruder design and process conditions on ultrafine CaCO3 dispersion into PP Type de document : texte imprimé Auteurs : M. Bories, Auteur ; M. A. Huneault, Auteur ; P. G. Lafleur, Auteur Année de publication : 1999 Article en page(s) : p. 234-240 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Highly filled calcium carbonate (CaCO3)/ polypropylene (PP) blends were compounded using an intermeshing corotating twin-screw extruder. The effect of screw configuration, rotation speed, flow rate, filler feed port position and barrel temperature on dispersion of calcium carbonate into polypropylene was investigated. A method based on image analysis of optical transmission micrographs obtained from 25 micron thick films was found to be quick and reliable for evaluating the state of dispersion in the filled systems. The dispersion state affected the mechanical performance of the systems. In particular, falling weight and unnotched Izod impact resistance decreased significantly as dispersion got poorer. Mechanical properties were correlated with the relative volume concentration of agglomerates in the blend. Note de contenu : - EXPERIMENTAL : Materials - Compounding - Dispersion evaluation technique
- RESULTS AND DISCUSSION : Effects of process conditions - Effects of process configuration - Effect of solid concentration - Statistical analysis - Effect of dispersion on mechanical propertiesDOI : 10.3139/217.1551 En ligne : https://drive.google.com/file/d/1V3IiL9OLCUgltY1t8w9YW4RDfAc2C5Sg/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16134
in INTERNATIONAL POLYMER PROCESSING > Vol. XIV, N° 3 (09/1999) . - p. 234-240[article]Réservation
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Titre : Profile die design based on flow balancing : Balancing with flow separation Type de document : texte imprimé Auteurs : P. Saha, Auteur ; J. Å vábÃk, Auteur Année de publication : 1999 Article en page(s) : p. 247-253 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : This paper presents a methodology for the design of profile dies based on the Cross Flow Minimization Method. The flow balancing is described for cases where the flows are balanced by varying the die land length combined with the flow separation. Three different approaches were utilized in the die analysis. First, the flow in two proposed profile dies was calculated by substituting the flow domain by a set of simple geometries. The second approach applied the Cross-Sectional Calculation method, while the last method is a fully 3D FEM non-isothermal calculation. The results are verified by comparison with experimental data. It is shown that each of the calculation procedures may be the choice of preference depending on the geometrical complexity. Note de contenu : - INTRODUCTION : Flow balancing methods - Numerical procedures
- CASE STUDY : Material properties - Profile shape requirements
- EXPERIMENTAL : Die design considerations - Simple geometries (SG) calculation - Cross sectional (CS) calculation - Fully 3D FEM - Comparison of the three calculation methods - Experimental dataDOI : 10.3139/217.1550 En ligne : https://drive.google.com/file/d/1A12K6OpOtsQsyMAfZVMlwCOcqIlDpVp9/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16135
in INTERNATIONAL POLYMER PROCESSING > Vol. XIV, N° 3 (09/1999) . - p. 247-253[article]Réservation
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Titre : Capillary flow of hard-metal carbide powder compounds Type de document : texte imprimé Auteurs : B. Hausnerova, Auteur ; P. Saha, Auteur ; J. Kubát, Auteur Année de publication : 1999 Article en page(s) : p. 254-260 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Experimental data relating to capillary flow of hard-metal carbide powders compounded with various polymeric binders are presented. Such powder - binder mixtures are used for the production of sintered hard-metal carbide components, mainly by injection moulding. In addition to measurements of their rheological behaviour in a capillary rheometer, the compounds were also subjected to thermo-gravimetric analysis in order to assess the ability of the binder to debind properly. The binder composition was varied from paraffin wax and its combinations with polyethyleneglycols to multi-component binders consisting of polyethyleneglycol, polyethylene, ethylene/vinyl acetate copolymer, and paraffin wax. Two kinds of hard-metal carbide powders differing in particle size distribution (uni-modal, bi-modal) were used. Although the compounds containing the simpler binder types had acceptable flow properties, their debinding behaviour was unsatisfactory. The multi-component compounds exhibited considerably better debinding; their flow was stable within a wide range of shear rates. Flow instabilities appearing at high solids loadings can limit the processability of the compounds used. DOI : 10.3139/217.1556 En ligne : https://drive.google.com/file/d/1c6uOA8iP5bmYr3V6Ofu9LYtervcxXaOt/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16136
in INTERNATIONAL POLYMER PROCESSING > Vol. XIV, N° 3 (09/1999) . - p. 254-260[article]Réservation
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Titre : Numerical simulation of the film casting process Type de document : texte imprimé Auteurs : Evan Mitsoulis, Auteur ; M. Beaulne, Auteur Année de publication : 1999 Article en page(s) : p. 261-275 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Numerical simulations have been undertaken for the film-casting process with viscoelastic fluids. Viscoelasticity is described by an integral constitutive equation of the K-BKZ type with a spectrum of relaxation times, which fits well experimental data for shear and extensional viscosities and the normal stresses measured in shear flow. Non-isothermal conditions are considered by applying the Morland-Lee hypothesis, which incorporates the appropriate shift factor and pseudo-time into the constitutive equation. A one-dimensional model derived from the conservation of momentum is used to approximate the thickness, while the stress free-surface condition is used to approximate the width. The resulting system of differential equations is solved using the finite element method and the Newton-Raphson iterative scheme. The method of solution was first checked against the Newtonian and Maxwell results for different film geometries. The simulations are compared to available experimental data and previous simulations in terms of film thickness, film width, and film temperature. Agreement between the experiments and the current simulations is considered good with subtle differences. Agreement is also considered good between the current one-dimensional simulations and previous two-dimensional simulations for viscoelastic fluids, in terms of width and thickness. The one-dimensional model is advantageous since the algorithm is relatively simple, convergence is almost guaranteed, and the computing time is short. Note de contenu : - MATHEMATICAL MODELING
- CONSTITUTIVE EQUATIONS : Isothermal newtonian model - Isothermal upper-convected Maxwell (UCM) differential model - Study of silagy et al - Isothermal upper-convected maxwem (UCM) differential model - Current study - Non-isothermal modified K-BKZ integral constitutive model -
- METHOD OF SOLUTION
- RESULTS AND DISCUSSION : Film casting of a newtonian fluid - Film casting of an upper-convected Maxwell (UCM) fluid - Comparison with three-dimensional simulations - Comparison with two-dimensional simulations - Non-isothermal film casting of polymer melts - Non-isothermal film casting of polymer melts - a parametric studyDOI : 10.3139/217.1554 En ligne : https://drive.google.com/file/d/1LZUwzCGYNHSBxzRIGvfM23OmH-qROS5N/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16137
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Titre : Breakage and buckling of fibrous reinforcements during fabrication of thermoplastic matrix composites Type de document : texte imprimé Auteurs : A. Cohen, Auteur ; M. E. Adams, Auteur ; G. A. Campbell, Auteur Année de publication : 1999 Article en page(s) : p. 276-281 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : The paper addresses the buckling of fibrous reinforcements which occurs due to motion of the amorphous matrix material during solidification. The motion of the matrix material is caused by a variation in cooling rate in different portions of a composite while the sample is cooling. In the course of this study, samples were prepared with a fiber reinforcement sandwiched between premolded sheets of polycarbonate. Samples were either processed in a two-cavity, 'dogbone' shape mold or in a rectangular, single-cavity mold matched die compression mold. In order to visualize the motion of the molten matrix material, strands of polycarbonate blended with carbon black were mounted into the matrix. The buckling behavior demonstrated sensitivity, to the amount of reinforcement observed with single and multiple filaments of carbon and Kevlar and bundles of carbon fiber tows. This paper provides scaling considerations indicating the sensitivity of the observed effects to processing conditions and concludes with a discussion of the implications for load carrying capabilities of composites. Note de contenu : - EXPERIMENTAL : Outline of the experimental program - Sample preparation procedure
- A REVIEW OF THE EXPERIMENTAL OBSERVATIONS : "Dogbone" experiments - Experiments with rectangular samples
- EVALUATION OF THE EXPERIMENTAL OBSERVATIONS
- GOVERNING EQUATIONS
- SIMPLIFICATION AND MODIFICATION OF THE CONTINUITY CONDITION
- EVALUATION OF THE COOLING RATES
- INTERPRETATION OF THE MOMENTUM BALANCE
- APPLICATION OF THE THEORETICAL MODELDOI : 10.3139/217.1555 En ligne : https://drive.google.com/file/d/15Dc353i_6ODjhFo8HREOJNapOn7PJ0oA/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16138
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Titre : Long glass fibre reinforcement of thermo plastics : Experimental and theoretical results for injection and blow moulding, sheet and pipe extrusion Type de document : texte imprimé Auteurs : S. F. Bush, Auteur Année de publication : 1999 Article en page(s) : p. 282-290 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : The paper summarises the main experimental and theoretical results from a long-term programme of research (SAFIRE) to produce and apply long glass fibre compounds to the extrusion of pipes, sheets and profiles and to injection, blow and roto moulding. The overall objective is to obtain the pro-cessing speeds associated with short fibre reinforced thermoplastics with the reinforcement efficiencies associ-ated with prepositioned or prepreg thermoset composites. Extrusion and injection moulding are now in the commercial domain, with industrial scale trials underway in the other technologies.
Long glass fibres are defined by their ability to form lace-like mat structures within the polymer melt which persist into the solid state. Such structures, which greatly increase both melt strength and solid state thermo mechanical properties, can be formed with fibre volume concentrations (c) as low as .01. The formation of mat structures depends on the number N of virtual touches per filament. A minimum of around five touches is generally needed. From earlier work N is given as A.c.l/d. A varies with mean fibre orientation in the mat: for the random in-plane case it is approximately 8/π2, so that in contrast with typical fibre suspensions (c≤d/l) extremely strong particle-particle interactions are involved in the melt state.
In the solid state, tensile strength is measured and modelled in terms of number average fibre length (l) and diameter (d), polymer yield strength, fibre distribution efficiency, interfacial shear strength and a specially defined matrix stress magnification factor M. The role of patented fibre management devices in optimising these variables as they appear in the solid state is defined and described.Note de contenu : - STRUCTURE OF LONG-FIBRE MATS
- OVERALL SAFIRE PROCESSES : Production of LGF granules - Fibres management devices
- FLOW SHAPING : Motion of a fibre with strong particle-particle interaction - Motion in a particular flow field - Shaping flows with static devices
- EVALUATION OF SHORT TERM TENSILE PROPERTIES AT ROOM TEMPERATURE : Sample preparation - Tensile properties and the matrix stress amplification factor MDOI : 10.3139/217.1544 En ligne : https://drive.google.com/file/d/1F_PNDZc3pOnxD_4Y2DCNDtodAP3Y2th0/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16139
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Titre : Fitting of K-BKZ model parameters for the simulation of thermoforming Type de document : texte imprimé Auteurs : P. Novotný, Auteur ; P. Saha, Auteur ; K. Kouba, Auteur Année de publication : 1999 Article en page(s) : p. 291-295 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Thermoforming is characterized by large deformations of the polymeric material being processed. The simulation is complicated by the fact that an elastic material model cannot principally describe the thermoforming deformation precisely. In this respect non-linear and time-dependent viscoelastic behavior of the polymeric material has to be taken into account. In our research we used the K-BKZ model capable of describing viscoelasticity and large deformations. The parameters of this model were determined experimentally using a simple testing method. The method is derived from plug-assisted thermoforming. Computer analysis was used to evaluate the experiments: The tests performed were simulated using FEM (Finite Elements Method) repeatedly with different material parameters. The material parameters leading to a minimum sum of squares of differences between experimental and simulated values estimate the tested material behavior. It has been found that the final shape and the wall thickness distribution show a significant dependence on the material properties in case of deep thermoforming. Note de contenu : - Theoretical background of the K-BKZ model
- Model parameter estimation-measurements
- Model parameter estimation-fitting
- Material properties influenceDOI : 10.3139/217.1543 En ligne : https://drive.google.com/file/d/1dgJPEOVuz80zHMQYqB5Cu9LONKggq-6S/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16140
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Titre : Tensile damage in ternary melamine-formaldehyde composites Type de document : texte imprimé Auteurs : P.-O. Hagstrand, Auteur ; R. W. Rychwalski, Auteur Année de publication : 1999 Article en page(s) : p. 296-308 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : A new ternary planar random fiber composite (PRFC) is studied. It is a discontinuous glass fiber-reinforced, alumina trihydrate (ATH)-filled, melamine-formaldehyde (MF)-based composite of high fire resistance. Composites were manufactured from a commercially available molding compound using a Chopped Strand Mat (CSM), and compared with other ones obtained by varying the composition. Also, a comparison is made for grades with a high content of ATH but with different fiber architectures, realized by replacing the CSM mat by a needled mat.
The amount and type of tensile damage is shown. An elastic-damage type parameter is discussed and used. In-situ Scanning Electron Microscopic (SEM) observations on polished surfaces of samples mounted in a tensile stage and subject to tensile load, and observations on as-obtained surfaces are made. Stress-strain behavior depending on damage is analyzed, and possibilities of improvement of mechanical properties are postulated.Note de contenu : - MEASURE OF DAMAGE : Damage parameter - Irreversible strain
- REINFORCED MELAMINE COMPOUND (RMC) : Melamine-formaldehyde (MF) - Glass fibers - Alumina trihydrate [33]
- EXPERIMENTAL : Materials - Monotonic and cyclic straining - In-situ SEM - Stress relaxation
- RESULTS AND DISCUSSION : Monotonic stress-strain behavior - Cyclic stress-strain behavior - Viscoelastic behavior - In-situ SEM results - Stained sample studyDOI : 10.3139/217.1548 En ligne : https://drive.google.com/file/d/1EEoclUMfv-CFH8ndNNErn8rJd811MB86/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16141
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| Code-barres | Cote | Support | Localisation | Section | Disponibilité |
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| 001009 | - | Périodique | Bibliothèque principale | Documentaires | Disponible |
