Jean-Christophe QUANTIN
Ecole des Mines d'Alès, CMGD, Faculty Member
- Research in Polymer ScienceHead of a Technological Department focused on Design, Materials Engineering, Mechanical Engineering and Mechatronicsedit
This paper deals with the optical and colorometric properties of the recycled polymer during numerous internal reprocess. The effects of the number of grinding-injection cycles, three process parameters (material temperature, mold... more
This paper deals with the optical and colorometric properties of the recycled polymer during numerous internal reprocess. The effects of the number of grinding-injection cycles, three process parameters (material temperature, mold temperature, and injection rate) were investigated. One most limit for this kind of study is the large number of experiments that requires long time and significant investments. The idea is to vary five injection parameters (Tmaterial, Tmold, injection rate for five injection cycles using statistical approach. The five variables were investigated at three industrial used levels. The number of recycling varies from cycle 0 to cycle 4 at five levels. The complete matrix for screening was designed using D-optimal quadratic design. The experimental design was generated with the statistical software MODDE 10.1-Umetrics. A set of 42 experiments was carried out to determine the influence of injection parameters, polluant and recycling on the appearance properties...
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La fabrication additive et plus particulierement la fabrication par depot de fil fondu est une technologie qui prend de plus en plus d’ampleur dans les milieux industriels et grand public. En effet, cette technologie permet la fabrication... more
La fabrication additive et plus particulierement la fabrication par depot de fil fondu est une technologie qui prend de plus en plus d’ampleur dans les milieux industriels et grand public. En effet, cette technologie permet la fabrication de prototypes et de maquettes, mais aussi, de plus en plus, de pieces de petite serie . L’utilisation croissante de ce procede de fabrication necessite l’usage de materiaux qui ont un impact plus faible sur l’environnement. C’est dans ce contexte que des biocomposites ignifuges sont etudies afin de repondre aux normes de securite de l’utilisateur et aux reglementations environnementales. De ce fait, la reaction au feu des materiaux pour la fabrication additive est de plus en plus etudiee. Le poly(acide lactique) (PLA) est un polyester aliphatique biosource, compostable, biocompatible et non toxique. Cependant, la stabilite thermique et la reaction au feu du PLA ne sont pas satisfaisantes. Le systeme retardateur de flamme utilise dans cette etude es...
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Cette etude porte sur la mise en oeuvre d'un modele mecanique mixte (multicouche-autocoherent), de maniere a prevoir le module d'elasticite de composites. Le materiau etudie est un polypropylene charge fibres de verre broyees.... more
Cette etude porte sur la mise en oeuvre d'un modele mecanique mixte (multicouche-autocoherent), de maniere a prevoir le module d'elasticite de composites. Le materiau etudie est un polypropylene charge fibres de verre broyees. Afin de tester differents produits, des lots de fibres de longueurs differentes ont ete utilises. Afin d'alimenter le modele, nous avons procede a des determinations semi-automatiques par analyse d'images couplee avec la microscopie. Il s'agit de mesures de taille (granulometrie) et d'orientation des fibres au sein de leur matrice thermoplastique. Les resultats donnes par le modele sont en bon accord avec ceux obtenus par voie experimentale (essais de traction uniaxiale).
This study evaluated the potential of using poly(lactic acid)/poly(e-caprolactone) (PLA/PCL) blends for fused filament fabrication (FFF) and assembly with pure PLA for biomedical applications. PLA/PCL binary blends were meltblended in a... more
This study evaluated the potential of using poly(lactic acid)/poly(e-caprolactone) (PLA/PCL) blends for fused filament fabrication (FFF) and assembly with pure PLA for biomedical applications. PLA/PCL binary blends were meltblended in a twin-screw extruder at different ratios (20/80 to 80/20) and then formed into filaments with a calibrated diameter for FFF. The microstructure, surface properties, and rheological and mechanical behaviors of the blends were assessed. The blends were immiscible but showed signs of adhesion between the phases. It was determined that the fibrillar morphology of inclusions for PLA/PCL ratios higher than 30/70 proved to be driven by the manufacturing process. The tensile mechanical behaviors of printed and injected samples were similar, and their Young's modulus was simulated using Halpin-Tsai and Mori Tanaka models based on the sample microstructure. The ductility of the blends was strongly driven by the behavior of its majority phase. Finally, specific samples were designed to characterize the tensile strength between PLA and its blends by entangling layers of both materials. The strength of the assembly was found to be dependent on the phase that was continuous and was governed by the strength and the viscosity of the blend.
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Objectives: Reconstruction of endodontically treated posterior teeth use now dual or chemical cure core build-up materials. Core build-up materials have mechanical properties still unknown. This properties have consequences on survival of... more
Objectives: Reconstruction of endodontically treated posterior teeth use now dual or chemical cure core build-up materials. Core build-up materials have mechanical properties still unknown. This properties have consequences on survival of reconstruction and the tooth. For the same material family, the operator feelings may be very different depending on resin flowability. The aim of this study was to evaluate the viscosity and some mechanical properties of different resins. Methods: Core build-up materials were subjected to a rheological study: Steady rheometry - time effects: Voco Rebilda weiss and Ivoclar Multicore flow. Oscillatory rheometry: effects of frequency and time: Voco Rebilda dentin and Itena Dentocore A3 (rotational rheometer ARES-TA Instruments). Dynamic vibration tests Voco Rebilda (blau1, blau2, weiss and dentin). Micro-indentation: Voco Rebilda (blau, weiss and dentin). Comparing the evolution of micro-Vickers hardness : Ivoclar MultiCore flow and Voco Rebilda dent...
ABSTRACT The effects of an epoxide-based chain-extender (CE) on the properties of poly(lactic acid) (PLA) foams obtained by chemical foaming extrusion using 4 wt.% of chemical foaming agent (CFA) were studied. PLA/CE blends with different... more
ABSTRACT The effects of an epoxide-based chain-extender (CE) on the properties of poly(lactic acid) (PLA) foams obtained by chemical foaming extrusion using 4 wt.% of chemical foaming agent (CFA) were studied. PLA/CE blends with different weight ratios of CE were initially processed using a co-rotating twin-screw extruder. PLA/CE foams were then produced using a single-screw extruder. Various PLA/CE foams characterizations, including solution viscosity, thermal properties (DSC, TGA), cellular structure (void fraction, cell size, open cell content), mechanical and dynamic rheological behaviors, were investigated. Results show that the addition of CE enhances the viscosimetric average molecular weight and rheological properties (viscosity and storage modulus) of PLA, but it has no significant effects on the thermal properties of PLA, except the occurring of a cold crystallization. The CE incorporation also led to a decrease in the void fraction of cellular PLA, in the cell size and in the open cell content and to an increase in the cell density. Furthermore, the tensile mechanical properties such as yield stress and elongation at break of cellular materials increased with the addition of CE.
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ABSTRACT The degradation of poly(lactic acid) (PLA) during thermal-mechanical processing was studied and the influence of processing conditions on degradation rate was determined by size exclusion chromatography coupled with multi-angle... more
ABSTRACT The degradation of poly(lactic acid) (PLA) during thermal-mechanical processing was studied and the influence of processing conditions on degradation rate was determined by size exclusion chromatography coupled with multi-angle light scattering (SEC-MALS). A two-parameter model accounting for both chain scission and recombination processes was used to describe the experimentally observed molar mass distribution. The degradation and recombination rate constants were determined for undried and dried PLA. It was highlighted that the effect of processing temperature (in the 170-210 °C range), processing time (until 30 min) and shear rate (rotor speed varying from 0 to 150 rpm) on molar mass reduction can be relatively well simulated insofar as self-heating related to the mechanical energy conversion into heat was taken into account. The influence of melt processing on the thermal behaviour of PLA was also investigated using temperature modulated differential scanning calorimetry (TMDSC). It was evidenced that the molar mass reduction affects the crystallizability of PLA. Cold crystallization temperature progressively decreases with decreasing molar mass and the metastable α’phase is formed in place of the stable α phase. The α’ phase can be partially converted into α form during melting giving rise to a double-melting peak. The two peaks can be separated using reversing and non-reversing signals confirming that recrystallization of the α’ form occurs.
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ABSTRACT It is well known that application of a coupling agent to a glass fiber surface will improve fiber/matrix adhesion in composites. However, on commercial glass fibers the coupling agent forms only a small fraction of the coating,... more
ABSTRACT It is well known that application of a coupling agent to a glass fiber surface will improve fiber/matrix adhesion in composites. However, on commercial glass fibers the coupling agent forms only a small fraction of the coating, the larger part being a mixture of processing aids whose contribution to composite properties is not well defined. The interfacial region of the composite will therefore be affected by the coating composition but also by the chemical reactions involved in the vicinity of the fiber and inside the surrounding matrix. The main feature of this study consists in dividing the interface region into two separate regions: the fiber/sizing interphase and the sizing/matrix interphase. A wide range of techniques was used, including mechanical and thermomechanical tests, infrared spectroscopy, gel permeation chromatography, carboxyl end group titrations, extraction rate measurements, and viscosity analysis. Experiments were performed on poly(butylene terephthalate) composites and results indicate that the adhesion improvement is due to the presence of a short chain coupling agent and of a polyfunctional additive, which may react both with the coupling agent and the matrix. According to the nature of this additive, it may be possible to soften the interphase and then to increase the composite impact strength.
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ABSTRACT Short glass fiber/poly(butylene terephthalate) composites with different glass fiber treatments were characterized within a temperature range from −150°C to + 150°C by dynamic tests in torsion and tensile modes. Untreated fibers... more
ABSTRACT Short glass fiber/poly(butylene terephthalate) composites with different glass fiber treatments were characterized within a temperature range from −150°C to + 150°C by dynamic tests in torsion and tensile modes. Untreated fibers or fibers coated by silane coupling agents associated or not with sticking agents were used. It was observed that the magnitude of β and relaxations depends strongly on the microstructural parameters of such composites: fiber content, degree of crystallinity of the matrix, fiber length distribution, level of adhesion.
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ABSTRACT The present study aims at assessing the extrusion foaming characteristics of two commercial grades of poly(lactic acid) (PLA) using a chemical foaming agent (CFA). For each PLA the process was optimized based on a maximal void... more
ABSTRACT The present study aims at assessing the extrusion foaming characteristics of two commercial grades of poly(lactic acid) (PLA) using a chemical foaming agent (CFA). For each PLA the process was optimized based on a maximal void fraction criterion. The extruder die temperature significantly affects the void content (maximal for about 195 °C). An increase in the barrel temperature profile was also correlated with an increase in the void fraction. Moreover an increase in CFA concentration increased the PLA void fraction, and in some cases induced a decrease in cell density and an increase in cell size. Finally, an optimal value of 47% void fraction was obtained. Finally, optimally processed PLAs with varying CFA contents were tensile tested. The results pointed out that it was possible to observe significant decrease in the density and increase in some specific mechanical properties by controlling the extrusion foaming process.
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ABSTRACT The characteristics of thermosetting composite materials such as SMC are affected by the presence of reinforcements as a result of surface–matrix interactions. Surface treatments or sizings can significantly affect such... more
ABSTRACT The characteristics of thermosetting composite materials such as SMC are affected by the presence of reinforcements as a result of surface–matrix interactions. Surface treatments or sizings can significantly affect such interactions; hence the sizing selection may significantly affect SMC characteristics. The wetting properties of the unsaturated polyester matrix on glass fibres with different sizings have been studied by contact angle determination. In addition, the permeability of the glass fibres as well as their stiffness, the sizing solubility and swelling were also studied to understand the impregnation level of the glass fibres by the unsaturated polyester matrix before the curing reaction as a function of the sizing chemistry. The parameters that have been varied to determine the wetting and the adhesion properties provided by surface energies are the followings: (i) the sizing amount; (ii) the antistatic agent nature; (iii) the deposit method of this antistatic agent, and (iv) the film former nature. From these results in relation with the surface quality of corresponding moulded SMC panels, some of these glass fibres were selected. By using a statistical approach (principal components analysis (PCA)), it has been possible to conclude about the influence of the glass fibres characteristics on the surface quality. Correlations have also been established between the glass fibre characteristics, the material flow and the surface quality of the SMC panels.
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Advances in surface quality and a better understanding of the formation mechanisms of surface defects are required for SMC applications as body panels in the automotive industry. This study is focused on the influence of the material... more
Advances in surface quality and a better understanding of the formation mechanisms of surface defects are required for SMC applications as body panels in the automotive industry. This study is focused on the influence of the material formulation and SMC process on the surface quality, which is probably conditioned by the interactions between the paste and the fibres. The main
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ABSTRACT The dynamic mechanical behaviour of a series of poly(butylene terephthalate)/glass beads composites was studied as a function of filler ratio, filler size and surface treatment. Samples were subjected to compression-tension... more
ABSTRACT The dynamic mechanical behaviour of a series of poly(butylene terephthalate)/glass beads composites was studied as a function of filler ratio, filler size and surface treatment. Samples were subjected to compression-tension testing within a temperature range from -150°C to 150°C. The real part (E') of the dynamic modulus and the loss tangent (tan δ) were studied around β and α relaxations. It was observed that the magnitude of these relaxations decreased as the glass beads ratio increased. A similar decrease was observed at constant filler ratio with improving filler-matrix adhesion by a coupling agent. All these results might be due both to the matrix substitution by fillers and to the reducing of polymer chains molecular mobility in the vicinity of the interface. Using Hashin's correspondence principle, the viscoelastic behaviour of such composites was described by self-consistent models in the neighbourhood of the α relaxation and compared to experimental data.