Дисертації з теми "Fatigue des mousses polymères"
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Le, Bail Jean-Baptiste. "Modélisation du comportement mécanique sous chargement d’une butée d’amortisseur en mousse de polyuréthane : vers une démarche de dimensionnement en fatigue." Electronic Thesis or Diss., Brest, École nationale supérieure de techniques avancées Bretagne, 2022. http://www.theses.fr/2022ENTA0003.
Повний текст джерелаPolyurethane foam jounce bumpers are widely used in the automotive industry. Their main function is to absorb vertical shocks to the wheels and contribute to the integrity of the vehicle suspension. The mechanical response of this type of parts implies to take into account different mechanisms, from the buckling of the walls of the part to the self-contact through the geometrical non-linearities. The current characterization of these polyurethane foam jounce bumpers in fatigue is currently limited to the customer’s specifications and to the tests predefined by him. The objective of this thesis is to carry out a complete experimental characterization of the mechanical behavior in order to identify an Hyperfoam type behavior law. This characterization is also based on imaging techniques, SEM and tomographic, in order to characterize the link between the microstructure and the mechanical behavior of the jounce bumper. This study should allow to define a global approach for the fatigue design of polyurethane foam jounce bumper
Chen, Xiao Yuan. "Mousses structurales asymétriques de polymères." Thesis, Université Laval, 2008. http://www.theses.ulaval.ca/2008/25085/25085.pdf.
Повний текст джерелаMechraoui, Ahmed. "Sandwich composite de mousses polymères." Thesis, Université Laval, 2010. http://www.theses.ulaval.ca/2010/27452/27452.pdf.
Повний текст джерелаThe aim of this work is to produce and characterize polypropylene structural composite foams. To do so, the work is divided in three parts. The first part is devoted to study the reinforcement of polypropylene with hemp fibres by changing the fibre content, fibre size and coupling agent concentration. Micrographs are used to explain the results of the mechanical properties measured under tensile and flexural stress. It is found that 2% of coupling agent gives the optimum modulus values. In the second part, polypropylene foams are produced by compression moulding with different concentrations of blowing agent to determine the effect of density reduction and density profile on the tensile and flexural properties. The morphological characteristics (cell size, cell density and skin thickness) of the foams are also examined. It is found that the use of the complete density profile is necessary to predict with high precision the mechanical results. Finally, sandwich structures are produced with different skin ratio and core densities. A complete morphological analysis is reported with mechanical properties (tensile and flexural). It is shown that the simple law of mixture and the square power-law combined with the density profile are enough to predict the effect of the skins and core, respectively.
Guillermic, Reine-Marie. "Propriétés physico-chimiques des mousses : études approfondies sur des mousses modèles et études exploratoires sur de nouvelles mousses." Phd thesis, Université Rennes 1, 2011. http://tel.archives-ouvertes.fr/tel-00573721.
Повний текст джерелаDeverge, Mickaël. "Propriétés mécaniques et rhéologiques des mousses de polymères réticulés." Le Mans, 2006. http://cyberdoc.univ-lemans.fr/theses/2006/2006LEMA1008.pdf.
Повний текст джерелаThe use of cross-linked polymer foams gains ground more and more, particularly for acoustic absorption. This work present new approaches for the characterization of these materials, which have a behavior in hysteresis with 3 distinct zones. First the linear behavior is presented on a large frequency band with the application of the Time-temperature Superposition (TTS) principle. 2 aspects are thus shown: a weak portion of the skeleton takes part in the stress transmission, and the elastic modulus at null frequency decrease with the pore size. Then an extension of the magnetism Preisach's theory is presented for great deformations: hysteresis is thus modelled starting from a distribution of microscopic hysterons. Lastly, 2 compressive relaxation mechanisms are distinguished. Principal relaxation decreases stress by topological rearrangement of the foam beams
Deverge, Mickael. "Propriétés mécaniques et rhéologiques des mousses de polymères réticulés." Phd thesis, Université du Maine, 2006. http://tel.archives-ouvertes.fr/tel-00133963.
Повний текст джерелаDiverses méthodes ont été développées afin de caractériser ces matériaux, en particulier leur domaine linéaire, zone privilégiée pour l'absorption acoustique et la détermination des paramètres mécaniques courants. Cependant ces caractérisations restent souvent limitées à une faible plage fréquentielle. Une première étude présente ici le comportement linéaire sur une large gamme de fréquences grâce à l'application du principe de Superposition Temps-Température (TTS). L'utilisation du TTS sur une famille de mousses obtenues avec le même polymère, de même densité, mais dont la taille des pores est différente, met en évidence deux aspects importants: seulement 3 % du squelette solide participe à la transmission de la contrainte, et le module élastique à fréquence nulle décroît avec la taille des pores.
Les mousses de polymères sont certes souvent utilisées dans leur domaine linéaire, mais leur comportement mécanique diffère à de plus forts niveaux de déformation. Les courbes en contrainte-déformation présentent un comportement en hystérésis, avec trois zones de comportement distinctes (linéaire, flambement et densification). Il existe d'autres phénomènes en hystérésis qui ont été plus simplement modélisés, par exemple à l'aide de la théorie de Preisach-Krasnoselskii-Mayergoyz (PKM) issue du magnétisme. Une seconde partie de ce travail présente une nouvelle extension de cette théorie PKM aux mousses de polymères réticulés à cellules ouvertes, soumises à de grandes déformations: nous pouvons ainsi modéliser l'hystérésis observée expérimentalement, à partir d'une distribution d'hysterons microscopiques contenus dans un espace de Preisach-Mayergoyz.
Dans une troisième partie, l'influence de l'histoire passée des contraintes sur la mesure des paramètres mécaniques d'une mousse est étudiée, et plus particulièrement la rhéologie de ces mousses dans le cadre de la relaxation de compression, en distinguant deux mécanismes, l'un en zone linéaire de chargement et l'autre en dehors. Liée à l'histoire des contraintes passées, ce second mécanisme de relaxation permet la réduction des contraintes par réarrangement topologique des poutres de la mousse.
Mazzon, Elena. "Développement, étude physico-chimique et optimisation de mousses polymères biosourcées." Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT197.
Повний текст джерелаThis thesis focuses on the development of a new generation of bio-based polymer foams able to produce low density core in sandwich structure for automotive applications. The polymer formulations used in this research contain two different epoxy compounds, epoxidized linseed oil (ELO) and the epoxidized glycerol (GE). Combined in varying proportions, they were cured with two different hardeners, isophorone diamine (IPDA) or methyl tetrahydrophthalic anhydride (MTHPA). Ternary formulations “ELO – GE – hardener” were characterized by a multi-techniques approach (DSC, TGA, rheometry in steady or dynamic mode) in order to establish structure-property relationships. The production of polymeric-foam materials was carried out by tuning a chemical reaction which takes place during curing. Sodium bicarbonate and potassium bicarbonate were used as harmless foaming agents. In order to improve the final performances of the foams, the ratio GE/ELO was increased in the reactive formulations based on IPDA hardener. But, such modification provokes also the thermal degradation of the system because of the high exothermicity of the curing reaction. The introduction of “exothermicity regulators” that undergo endothermic transformations allowed to control the excess of released heat and consequently, to prevent the material degradation. A last class of hardener was also studied and made it possible after optimization the production of foams with good ultimate properties. To conclude, a large range of biobased and lightweight rigid foams able to be produced in a few minutes was developed
Gropplero, di Troppenburg Giacomo. "Dispositifs microfluidiques dans les mousses polymères : fabrication, modélisation et applications biologiques." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAI060.
Повний текст джерелаMicrofluidics and an appropriate substrate are essentials for the design of low-cost point-of-care diagnostic devices. The particular mechanical and structural properties (porosity, elasticitydots) of polymeric foam are unique among the other widespread materials in microfluidics (PDMS, paper, plastic materials, glass, silicondots). A systematic screening of the different capabilities provided by polymeric foam as a new substrate for microfluidics is offered in this thesis. First off, a shaping process is proposed for the production of fluidic microsystems. This new process relies on the combined usage of a polymeric foam and an elastomer to produce highly elastic fluidic systems that keep the initial structural properties of the foam. Based on a controlled and repeatable embossing technic, the process is compatible with industrial production. A coupled numerical model also allows its optimization. The resulting foam microfluidic devices have, besides capillarity, a decisive asset : the option of a manual compression or an external peristaltic actuation for a contamination-free control of the microfluidic flows. The peristaltic actuation can function as a pump and as a valve. A lumped elements model enables a dynamic reproduction of the fluidic behavior inside the foam channels. To ensure proper integration in low-cost portable devices, the fundamental stages of a diagnostic test (retrieval and preparation of a sample, detection) are validated. We show that filtration of objects of only a few tens of micrometers in size is possible. The foam devices can also be chemically functionalized to optimise the capture of specific biological targets. The fluorescent or colorimetric detection of biological elements is equally possible by means of isothermal DNA amplification. Finally, a blood typing prototype gives access to the blood group of a whole blood sample in a few minutes. This last test is carried on an integrated device which highlights the main benefits of a foam device : robustness, user-friendly, embedded reagents, multiple materials combination, transport of a biological sample by external compression controlled by an operator, direct readout of a result in a few minutes
Pradel, Pierre. "Etude de la compaction dynamique de mousses polymères : Expériences et modélisation." Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2017. http://www.theses.fr/2017ESMA0035/document.
Повний текст джерелаPolymeric foams are widely used in many industrial applications as thermal insulators, structural materials or shock mitigators. Indeed, they are light weight materials with an excellent weight /stiffness ratio and low production costs. One of the applications which interests the CEA is the protection of structures against mechanical loadings generated by laser irradiation or high velocity impact of small debris.The main objective of this PhD thesis is to investigate the mitigation capability of an expanded polyurethane foam and an epoxy syntactic foam against extremely fast (> 106 s−1) and intense(> 10 GPa) dynamic loadings. Cyclic quasi-static tests and dynamic experiments have been performed to investigate the behavior of these two foams for strain rates ranging from 10−3 to 106 s−1. Analysis of the experimental results shows that these polymeric foams have an elastic behavior phase followed by a compaction phase with significant permanent sets. Compaction thresholds are about 9 MPa for the polyurethane foam and 30 MPa for the epoxy foam under quasi-static loadings and around 21 MPa for the polyurethane foam and 72 MPa for the epoxy foam for strain rates above 104 s−1.Two porous compaction models are developed to represent the macroscopic behavior of these foams for such strain rates. The parameters are identified from the results of dynamic compression experiments (gas gun, low inductance generator). The validity of the models is tested by comparing calculated velocity profiles with an explicit hydrocode and velocity profiles measured during the experiments. These models are then used to analyze the results obtained with electron beam irradiation and laser-driven shock experiments. We demonstrate that the studied polymeric foam shave high mitigation capabilities and that the models are valid for high strain rates
Larochette, Mathieu. "Mousses de polymères : étude des procédés de synthèse et de mise en forme." Pau, 2007. http://www.theses.fr/2007PAUU3016.
Повний текст джерелаPolymer foams are used for many applications thanks to their properties: lightness, insulation, impact resistance. . . In this work, we studied the elaboration of two kind of materials: polyurethane foam and extruded polystyrene foam. In the case of polyurethane, the correlation between the kinetic of polymerization and the foaming is important. For the polystyrene, we shown that the residence time distribution theory modelize properly the extrusion process. We found a relationship between the structural anisotropy and the thermal anisotropy coupling an experimental and a numerical approaches. The morphological anisotropy observed on industrial foam does not permit to observe the anisotropy of temperature field
Caty, Olivier Maire Eric. "Fatigue des empilements de sphères creuses métalliques." Villeurbanne : Doc'INSA, 2009. http://docinsa.insa-lyon.fr/these/pont.php?id=caty.
Повний текст джерелаCaty, Olivier. "Fatigue des empilements de sphères creuses métalliques." Lyon, INSA, 2008. http://theses.insa-lyon.fr/publication/2008ISAL0084/these.pdf.
Повний текст джерелаMetal hollow spheres can be piled up and soldered together to form a cellular material. The initial hollow spheres exhibiting a mono-disperse size and thickness, the resulting material is rather homogeneous. This kind of material allows a remarkable flexibility in terms of microstructural design. The thickness and diameter of the spheres, the nature of the metal used (nickel, steel. . . ) can be varied. This allows to tailor the microstructure in order to reach the target properties imposed by the design on the material. Before being able to tailor these properties and invent the material meeting a specific design (material by design), it is necessary to know the relation between the varying parameters and the resulting properties. This study aims at determining and modelling the effects of the microstructure of hollow spheres metals on their fatigue properties. Fatigue properties of a rather large range of metal hollow sphere structures were determined by mean of conventional fatigue tests. All the data were collected to build S-N curves. The constitutive material, the density, the thicknesses of the walls, the diameters and the fatigue loading mode were varied to determine the effect of each parameter. Tomographies of samples tested ex-situ reveal the different kinds of fatigue damage mechanisms and their influence on the macroscopic behavior. The three-dimensional X-ray tomographic images could also be used for meshing and to calculate the behaviour of the structure. This step has been done with a shell finite element model obtained from tomographic images. The model is enriched by a direct thickness measurement on the tomographic images. The values measured are affected to the shell elements. The model permits to determine the stress and strain field inside the microstructure. The fatigue behaviour has been modelled by post processing the proportion of yield elements and the size of yield areas. These models permit to determine the fatigue limit of numerically built hollow sphere structures and investigate parameters never experimentally studied
Deschanel, Stéphanie. "Dynamique des précurseurs de la rupture des matériaux hétérogènes : application aux mousses polymères vitreuses." Lyon, INSA, 2005. http://theses.insa-lyon.fr/publication/2005ISAL0093/these.pdf.
Повний текст джерелаIn order to predict failure time of materials, a new approach has been considered : fracture can be viewed as a critical phenomenon. For some materials fracture can be seen as a clustering of microcrackes. We focus on heterogeneous materials (vitreous polymer foams) whose fracture can be described as a phase transition. Our main experimental tool is the monitoring of the acoustic emission signatures of the microfractures, which occur during mechanical tests. We highlighted diffuse microcrack nucleation and progressive localization into a dominating crack with a good fit of the energy by a power law. The exponet of this power law does not seem to depend neither on the material density, the loading mode, nor the behavior law. The time intervals between two damaging evants seem to be power law distributed only if the stress remains nearly constant for the most part of the test. A critical region where the cumulative energy could be described by a power law appears only for creep tests
Dos, Reis Francisco. "Homogénéisation automatique de milieux discrets périodiques : applications aux mousses polymères et aux milieux auxétiques." Thesis, Vandoeuvre-les-Nancy, INPL, 2010. http://www.theses.fr/2010INPL050N/document.
Повний текст джерелаThe first achievement of this work is to construct a unified and effective continuum equivalent to a lattice of beams, in the elastic domain, using a Bernoulli beam model. An extension has been done to calculate the elastic domain resistance of such lattices and to build an algorithm for monitoring the constitutive law taking into account work hardening. The choice of the asymptotic expansions leads to a classical continuous or to a micropolar elastic continuum. We restrict in this last case our study to lattices with centro-symmetric unit cells. The numerical codes developed provide the stress-strain relationship and the effective mechanical moduli. A wide variety of trusses has been studied, either existing or original, including typical geometries of foams and various auxetic lattices, exhibiting negative contraction coefficients. The results were systematically compared with data from literature and verified by finite element simulations with a good agreement. The homogenization in the plastic range has been limited to stretching dominated lattices. The equilibrium equations of the discrete asymptotic homogenization have been used to automatically obtain the elastic resistance domain for several trusses, and a return-mapping algorithm for the follow up of the stress-strain relationship including hardening has been conceived and implemented in a dedicated code. An isotropic hardening elastoplastic model of the beam has been used. The application of the algorithm to the simulation of a loading-unloading cycle shows a good agreement between the homogenized lattice and finite element simulations
Boukrim, Amale. "Mousses de polyuréthane à l’eau." Thesis, Pau, 2011. http://www.theses.fr/2011PAUU3033/document.
Повний текст джерелаBecause of their properties (low density, insulation, impact resistance. . . ), polymer foams are widely used. This work focused on polyurethane foams aims at : replacing physical blowing agents (CFCs, HFCs) by the carbon dioxide formed by the reaction of isocyanate and water & trapping a catalyst in the polyurethane network. The formation of water-blown polyurethane foams involves two reactions. The polymerization (or gelling) reaction which creates the polyurethane network. And the blowing reaction which generates carbon dioxide. A proper balance is required between the two reaction rates to obtain a foam with atisfactory properties. The kinetics of each reaction considered separately was studied. Thus, on one hand IRFT and rheology were used to study the kinetic of the polyurethane formation. Both linear and crosslinked polyurethane were studied. We showed the interest of using utanediol to control the structure of the linear polyurethane. The effect of temperature and nature and concentration of catalyst on the kinetics of polymersation was showed. Moreover, triethanolamine which contains amine groups ( catalyst) and hydroxyl groups (crosslinkingagent) was tested. One the other hand, an appartus was made to study the kinetic of the blowing reaction. We show that the following parameters : temperature, weight of the diisocyanate, nature and concentration of catalyst, have a relatively limited influence on the kinetics of release of carbon dioxide. A study of polyurethane foams based on a commercial fomulation showed that it is possible to replace the physical blowing agents by water
Liu, Yu. "Elaboration et étude des propriétés mécaniques des mousses d'aluminium et des métaux poreux polymères composites." Troyes, 2007. http://www.theses.fr/2007TROY0007.
Повний текст джерелаThe objectives of this work consist to manufacture new metal porous polymeric composites (MPPC) with interpenetrated structure and to characterize their mechanical behaviors under statical and dynamic loading. Firstly, we developed a technique of infiltration under a negative pressure to manufacture the open cell aluminium foams and MPPC. The optic observations were carried out in multi-scale. The characterizations of materials were carried out under uniaxial compression. The influences of the structural parameters on the compressive behaviors were clarified by SEM observations during compression. The elastic module was compared with the analytical models. These results obtained are completely restructed between the boundaries proposed in the literature. Secondly, the behaviors of indentation were studied. The relations between the response of indentation and the size and the geometry of plunger tip were illustrated. The size and the shape of the densification zone were observed and modelled by analytical models and the finite element simulation. Finally, the behaviour of impact was studied. The influences of experimental conditions and structural parameters on the behaviors of impact were illuminated
Ayoub, Georges. "Comportement en grandes déformations et fatigue des polymères : modélisation constitutive et prédiction de la durée de vie en fatigue." Thesis, Lille 1, 2010. http://www.theses.fr/2010LIL10076/document.
Повний текст джерелаTwo representative polymers are studied in this thesis: a semi-crystalline thermoplastic (polyethylene) and an elastomer (styrene-butadiene rubber SBR).A physically-based hyperelastic-viscoplastic model integrating the crystallinity effects is proposed to describe the mechanical behavior under large deformation of polyethylene. The capabilities of the proposed model to reproduce the mechanical behavior of typical thermoplastic (viscoplastic-hyperelastic) to the mechanical behavior more typical of elastomers (visco-hyperelastic) are demonstrated. The proposed model is modified by incorporating a non-linear viscous component to capture the mechanical behavior of polyethylene under cyclic loading. To describe the damage process under multiaxial cyclic loading of SBR, two complementary approaches have been used. The first one, based on the network alteration theory, allows describing the stress-softening until failure. The comparison between the proposed model and experimental results obtained under uniaxial cyclic loading highlighted the relevance of such approach. The second one, based on the continuum damage mechanics theory, aims to predict the multiaxial fatigue life under complex loadings of rubber-like materials. In this approach, the damage variable is derived from the cracking energy density. After identifying the damage parameters using uniaxial fatigue data, the predictive capabilities of the proposed model are highlighted under multiaxial loadings, combining tension and torsion tests
Dabo, Mouhamadou. "Analyse du comportement mécanique des mousses polymères : apport de la tomographie X et de la simulation numérique." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAE041/document.
Повний текст джерелаPolymer foams materials combine mechanical, thermal, chemical and optical interesting properties going with light weighting structures problems. However, to diversify their applications and make them even more efficient in health field, transportation or building, a fine study of the relationships between manufacturing processes to generated microstructures and resulting properties must be conducted. These mechanical properties are highly depending on the properties of material with which foams are made but also on the morphology of their microstructures (orientation, distribution and pore size, wall thickness). Thus it is crucial to quantify and measure these parameters to strive for a detailed understanding of the mechanical properties and define models capable of linking global behavior of cellular materials to bulk materials and microstructures. Working closely with research and development division of INTEREP, European leader in waterproof cellular rubber, an experimental characterization of the mechanical behavior of polymer foams of different natures and different topologies has been performed first. Then geometrical modeling was developed from micro structural observations of real foams in x-ray micro-tomography and from virtually generated microstructures through a physical description of polymer foams manufacturing process. Finally finite element simulation in 2D and 3D of these microstructures were coupled with the experimental characterization of bulk material allowing thus to reproduce and finely study deformation mechanisms experimentally observed on polymer foams and refine empirical behavior laws by taking into account additional characteristic parameter of cells statistical distribution in space like their location and their size distribution and shape
Twite, Kabamba Eddy. "Polymer foams and composites recycling : Rheological and Macromolecular Investigations." Thesis, Université Laval, 2010. http://www.theses.ulaval.ca/2010/27578/27578.pdf.
Повний текст джерелаDuquesne, Sophie. "Etude des procédés d'ignifugation de substrats polymères par revêtements intumescents : application aux polyuréthanes." Lille 1, 2001. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2001/50376-2001-Duquesne.pdf.
Повний текст джерелаConcernant le système PU/EG, une faible modification du processus de carbonisation naturelle du PU est observée. La caractérisation du processus de carbonisation, menée selon une approche physique met en évidence une aptitude à la déformation de la structure carbonée formée par dégradation du revêtement PU/APP. Aucours d'un incendie, cette structure va donc se déformer plutôt que de se fissurer et ainsi permettre un maintien des performances RF. Dans le cas du système PU/EG, l'épaisseur importante, la faible densité et, comme il est possible de le supposer la faible conductivité thermique du bouclier intumescent permettent de comprendre le mode d'action de l'EG
Safouane, Mahassine. "Drainage des Mousses Aqueuses : Rôle de La Rhéologie du Fluide Moussant." Phd thesis, Université Paris Sud - Paris XI, 2003. http://tel.archives-ouvertes.fr/tel-00011398.
Повний текст джерелаDans une première étape, nous avons confirmé l'effet de la viscosité de surface observé précédemment qui entraîne une transition de régime d'écoulement (parois rigides / parois mobiles) lorsque l'on augmente la viscosité de surface. En effet, d'un point de vue rhéologique, le tensioactif réduit la mobilité des interfaces sous l'action d'un écoulement. Une faible quantité d'alcool à longue chaîne (dodécanol) additionnée à un tensioactif augmente sa capacité moussante, car elle accroît notablement l'adsorption à l'interface du liquide et conduit à des interfaces rigides. Nous avons montré que le passage d'un régime à l'autre ne se fait pas de façon brutale. Ceci peut s'expliquer en terme de résistance équivalente : dans le cas limite des parois rigides, les interfaces présentent une forte résistance au cisaillement et donc la vitesse s'annule aux parois (écoulement de Poiseuille). Quand on diminue la viscosité de surface, cette résistance diminue et la contribution des bords de Plateau diminue. Elle est remplacée par la contribution des noeuds jusqu'au point ou elle domine complètement (écoulement de type bouchon). Des mesures de tension superficielle et d'élasticité de surface nous ont permis de confirmer le changement de la rhéologie de surface en présence de dodécanol.
Par la suite nous avons fixé la viscosité de surface de façon à avoir des surfaces rigides (en se basant sur les résultats précédents) et nous avons varié la viscosité de volume en utilisant un fluide newtonien (le glycérol). Dans ce cas nous avons observé aussi une transition de régime à très forte viscosité (30 mPa.s). Cette transition est sûrement liée à une diminution relative de la résistance de surface due à un couplage entre la surface et le volume.
Finalement nous avons considéré le cas de différents types de fluides non-newtoniens. L'utilisation d'un fluide viscoélastique sur le drainage forcé a montré un effet contre intuitif: on pensait ralentir le drainage en ajoutant un polymère flexible, du PEO, dans nos solutions moussantes or l'effet observé a été l'opposé. Nous avons attribué cette différence à une manifestation de la viscosité élongationelle du PEO qui intervient lors de la variation de la section des bords de Plateau au passage du front pendant l'écoulement. L'augmentation de la vitesse de drainage permet de réduire localement la fraction liquide et donc de réduire l'ouverture du bord de Plateau lors du passage du front. L'écart de vitesse entre une mousse faite avec une solution de glycérol et une solution de PEO disparaît quand on augmente la taille de bulle. Nous avons complété les mesures globales par des observations à l'échelle locale. Pour cela, nous avons étudié le drainage dans un seul bord de Plateau et mesuré la variation de la section pour deux solutions de glycérol et de PEO de même viscosité. L'ouverture de la section du bord de Plateau est plus importante dans le cas de la solution de glycérol.
Finalement une étude de l'effet de polymères ayant de fortes propriétés rhéofluidifiantes (du xanthane et du carbopole) a montré que le caractère rhéofluidifiant des solutions moussantes ne semble pas affecter le drainage. En effet, si on ramène la viscosité au taux de cisaillement crée dans la mousse, les solutions ont un comportement très similaire aux solutions de glycérol, avec une transition de régime à forte viscosité dans le cas du xanthane.
Hirschberg, Valerian. "Fourier transform rheology as a tool to determine the fatigue behavior of polymers." Doctoral thesis, Université Laval, 2019. http://hdl.handle.net/20.500.11794/34659.
Повний текст джерелаThis thesis proposes a new framework to analyse, quantify and predict the mechanical fatigue of amorphous polymer using a method based on the decomposition of the stress response via Fourier transform. In particular, fatigue tests were performed under strain controlled torsion and tension/tension deformation and the time data of the strain, torque and force were recorded and decomposed into linear and nonlinear contributions via higher harmonics. In particular, three concepts have been developed to quantitatively determine the time behavior of the samples. Firstly, the generation of macroscopic cracks was found to correlate with sudden increases in the I2/1 intensity. Secondly, an on-line method to predict the fatigue lifetime was developed, based on the rate of change of I3/1 with respect to the cycle number N (dI3/1/dN) before the onset of failure. This prediction was found to be more precise than Wöhler curves predictions since the correlations have on average much lower standard deviations (30 vs. 60%). Thirdly, a fatigue criterion solely based on mechanical nonlinearity was developed: the cumulative nonlinearity Qf. This parameter correlates the integral of the nonlinearity Q (Q = I3/1/yo²) until failure with the number of cycles to failure Nf. The standard deviation of the Qf vs. Nf correlation was found to be less than 30%, indicating that Qf is a more precise fatigue criterion than commonly used ones such as the cumulative dissipated energy density or the cumulative stress (±50%). Finally, these three concepts were successfully applied on different conditions (type of deformation, range of frequency, deformation amplitude) and polymers such as polystyrene (PS), polymethylmethacrylate (PMMA), styrene acrylonitrile (SAN) and polytertbuthylmethacrylate (PtBMA).
Merlet, Samuel. "Elaboration et caractérisation de poly(phénylquinoxaline)s poreux." Chambéry, 2006. http://www.theses.fr/2006CHAMS023.
Повний текст джерелаThe aim of this thesis is to develop new high performance polymeric materials with closed submicron porosity. The adopted strategy is an original foaming process based on the in-situ gas generation from pendant thermolabile group decomposition. A thermostable polymer matrix poly(phenylquinoxaline)s (PPQ) has been chosen, as well as the thermolabile group tertbutylcarbonate (Boc). A preliminary model study was performed to precisely define the adapted strategy. Grafting the Boc structure on phenol group was shown to be efficient and the thermal decomposition provides carbon dioxide and isobutene in a very clean and quantitative way, which should lead to a good control of the foaming process of the system PPQ + CO2 /isobutene. Different monomers bis(α-diketone)s were synthesized and polymerized with a commercial bis(o-diamine), leading to PPQ with pendant phenol groups. Depending on the experimental conditions are prepared several structures having various phenol contents and specific repartitions depending on the monomer or "statistic”/”sequenced" architecture. The functionalisation of these phenol groups into Boc thermolabile groups could lead to a gas concentration from 150 to 654 mg/g and a repartition derived from the phenol ones. Three key parameters enable a good control of the porous materials morphology. They are the gas concentration, the glass transition (Tg) of the polymer and the foaming temperature. Using high foaming temperatures lead to macroporous PPQ foams (ultra and microcellular foams) whose morphologies are similar with ones obtained after a conventional CO2 foaming process. Parameters of this macroporosity can be controlled by playing on the gas concentration and the Tg of the polymer. Moreover foaming of "sequenced" architecture (bloc copolymers) lead to the formation of ultra and microcellular foams with a double distribution of pores. This bimodal distribution is probably due to microscopic phase segregations. All studied polymers associated with moderated foaming temperatures enable the formation of nanocellular foams with closed porosity. This results show that it is possible to form and stabilize nano-cells (8-40 nm) from a nucleation and growth mechanism in a polymer matrix. The production of such very small sizes and high cell densities requires a high nucleation rate (elevated gas concentration) and a limited growth of nucleated nano-cells (elevated system viscosity). Among the studied structures, the PPQ-OH foams show the best compromise between a high gas concentration (345 mg/g) and a high Tg (370 °C) and lead to very interesting nanocellular materials (Φ: 8-11 nm – Nc: 4 1016 cells/cm3 – P: 14-16 %vol)
Chomard, Angèle Anne-Marie. "Fatigue thermique des matériaux polyuréthane : essais d'optimisation d'une formulation PU à base de polyester." Lyon, INSA, 1997. http://www.theses.fr/1997ISAL0088.
Повний текст джерелаRobin, Jean-Jacques. "Synthèse et application d'agents de compatibilisation par ozonisation de polymères." Montpellier 2, 1989. http://www.theses.fr/1989MON20204.
Повний текст джерелаAlchikh, Mohamad. "Vieillissement mécano-chimique du polyvinyldifluore (PVDF) dans la soude." Strasbourg, 2009. http://www.theses.fr/2009STRA6031.
Повний текст джерелаGay, Cyprien. "Adhésifs, mousses, copolymères, granulaires immergés, rides, tissus." Habilitation à diriger des recherches, Université Paris-Diderot - Paris VII, 2013. http://tel.archives-ouvertes.fr/tel-00778225.
Повний текст джерелаForey, Natacha. "Mousses renforcées en polymère ou particules : application à la remédiation des sols pollués." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0311.
Повний текст джерелаGiven the possible environmental and health issues occurring when facing a hydrocarbon polluted site, soil remediation is necessary. One of the in-situ technique to remediate a Light Non Aqueous Phase Liquid pollution is the use of foam. Because of its blocking effect, foam is able to create a water blocking barrier, to confine water beneath the floating pollutant. However, the main issue with this technique is the stability of foam facing the oily pollutant. Several options are currently under review to reinforce foam against oil, which includes polymer or particles addition.The present study thus describes the work performed to obtain an oil-resistant foam in porous media, with the use of polymer or solid colloidal particles.In the first part of the study, foamability and stability tests were performed in bulk to select a broad range of products used to formulate such foams. Then, sandpacks experiments were realized in 1D columns in order to optimize the foam injection parameters and finalize the choice of surfactant and additives. Column experiments showed how additives impacted foam strength. Polymer addition led to an increased flow resistance without improving foam strength while particles addition proved to reinforce foam resistance against oil. Those results were then applied to carry out 2D-tank experiments to study foam displacement in a vertical two dimensions’ porous medium. The 2D tank also helped to simulate a foam injection below an oily layer and observe foam behaviour. Finally, the methodology and constrains to take into account to perform a pumping test in a 3D-pilot, were presented in the outlook section
Deschanel, Stephanie. "Dynamique des précurseurs de la rupture desmatériaux hétérogènes : application auxmousses polymères vitreuses." Phd thesis, INSA de Lyon, 2005. http://tel.archives-ouvertes.fr/tel-00123253.
Повний текст джерелаCorre, Yves-Marie. "Poly (lactic acid) foaming assisted by supercritical CO2." Lyon, INSA, 2010. http://theses.insa-lyon.fr/publication/2010ISAL0106/these.pdf.
Повний текст джерелаLe polylactide (PLA), par son origine bio sourcée et ses propriétés de biodégradation, peut être une bonne alternative aux polymères issus du pétrole. Dans cet objectif, le moussage du PLA par CO2 supercritique a été évalué dans cette étude comme substitution au polystyrène expansé (PSE) pour la production d'emballages alimentaires. Du fait des propriétés rhéologiques faibles de ce type de polyester, une première étape d'extension de chaînes a été nécessaire afin de garantir des bonnes aptitudes au moussage du PLA. Suite a une caractérisation complète dans le domaine physico-chimique, rhéologique et thermique, une étude de moussage en mode batch sous CO2 supercritique a été réalisée. Les paramètres de moussage, le taux de modification du matériau ainsi que de l'apport de la cristallisation sur la morphologie cellulaire ont été évalués. En fonction de ces différents paramètres, des structures allant du micro-cellulaire au macro-cellulaire ont été obtenues
Barbara, Imane. "Synthèse de polymères macroporeux par polymérisation par étape en émulsion concentrée." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0045/document.
Повний текст джерелаPolyHIPEs are cellular materials obtained by polymerization within HIPEs « High Internal Phase Emulsions ». The polymerization occurs in the continuous phase of the emulsion allowing the creation of a solid matrix. The dispersed phase induces the porosity. PolyHIPEs are generally obtained by free-radical polymerization which restricts the choice of monomers. The majority of high performance polymers are obtained by polycondensation therefore it will be a great interest to enhance the variety of polyHIPEs available by using this technique. The objective of this work consists to synthetize polyHIPEs using polycondensation or polyaddition. Performing a step-growth polymerization within emulsion is a great challenge because this kind of reaction requires conditions generally incompatible with the stability of HIPEs. In the context of this work, we focused on the synthesis of polyurethane and polyester polyHIPEs. The homogeneity of the morphology of the materials was studied by varying several parameters, such: the nature of the emulsion (aqueous or non-aqueous, stabilized by surfactants or particles), the nature of the catalysts and the polymerization techniques. This work opens the access for the first time to polyurethane and polyester polyHIPEs. The results obtained are a starting point for further development in this field
Dubois, Julie. "Moussage de polymères par des procédés physiques." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0311.
Повний текст джерелаThis dissertation focuses on the production and study of microcellular polymer foams by gas dissolution foaming. Due to the novelty of this research field several experimental techniques have been improved or adapted to produce the foams but also to provide valuable information from the systems understudy. It is demonstrated that processing parameters, such as pressure and temperature, allow differentiating between our foaming routes, and present a significant influence on the foaming process and final characteristics of foam
Boukhili, Rachid. "Fissuration par fatigue des polyamides : mécanismes." Compiègne, 1985. http://www.theses.fr/1985COMPD005.
Повний текст джерелаLamnii, Hamza. "Effets du vieillissement Ultraviolet sur le comportement mécanique des polymères semi-cristallins en chargement cyclique et monotone : expérimentation et modélisation." Thesis, Lille 1, 2019. http://www.theses.fr/2019LIL1I107.
Повний текст джерелаThe polymers are used under different climatic conditions and can be subjected to several types of aging. In particular, exposure to ultraviolet (UV) modifies the chemical structure of the material, and leads to the degradation of their mechanical properties. UV radiation aging is the result of a competitive process of chain scission and post-crosslinking. Although there is abundant literature on the physico-chemical processes induced by UV on polymers, a limited number of studies have focused on the consequences induced on their mechanical properties, this number being even more limited when considering their fatigue life. This work focuses on the effects of UV radiation on the mechanical properties of semi-crystalline polymers and in particular on fatigue properties. The material chosen for this study is low density polyethylene (LDPE). The test pieces were exposed to different levels of UV irradiation and their lifetime was measured via cyclic fatigue tests. These tests were achieved at constant maximum stress amplitude. The results show a significant decrease in the lifespan with the increase of the absorbed dose. Through the principle of time-temperature equivalence, a slip factor has been introduced allowing the construction of master curves integrating both the effects of the absorbed dose and those of the fatigue loading frequency. On the other hand, an elastoplastic model has been developed to describe the fatigue behavior of polyethylene using two work hardening components: the first one is the kinematic hardening, the second being the entropic resistance defined from the macromolecular hyperelastic model, the so-called eight chain model. The model was then completed by integrating elastic damage using a thermodynamic framework as proposed by Lemaitre and Chaboche for fatigue in order to describe the process up to failure. The obtained results indicate that the developed model is able to capture in a satisfactory manner the fatigue behavior observed experimentally up to fracture, whether for high cycle fatigue or low cycle fatigue
Santiago-Medina, Francisco José. "Tanins condensés pour mousses rigides et nouvelles réactions de réticulations des matériaux polyphénoliques." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0248/document.
Повний текст джерелаAn alternative to industrial phenol or resorcinol industrial products may be tannins or lignin. Both are natural polyphenols, the tannin is extracted from different parts of plants, while lignin is usually obtained as a secondary product in the pulp and paper mill. These two products are the main basis on which I have worked during the development of this thesis. In a first part, a study of characterization and differentiation between different tannins with the same origin and that present a different behavior when used in the same application under the same conditions has been done. Highlighting the GPC as a fundamental technique for the differentiation between sulphited quebracho tannins. On the other hand, the interactions between different substances with tannin and with lignin have been studied. As the study of the reaction between diamines (such as hexamethylenediamine) with tannin and lignin to obtain a polycondensed resins. Also, in this section have been obtained polyurethanes with at least 70% of natural substances in their preparation without using any isocyanate in the process. In addition, aldehydes derived from lignin, such as vanillin, have been used next to pine tannin for the manufacture of adhesives in the preparation of particleboards, obtaining satisfactory results according to European standards and from completely natural substances. Finally, within an industrial project the initial steps have been carried out for the development of a rigid tannin foam applicable by projection for the thermal insulation of buildings. Where a new mechanical foaming system has been developed for tannin foams based in fire-fighting foams or in the foams of the tunneling operations, this new system of foaming avoids the problems of shrinkage during the formation of the foam
Denay, Anne-Gaëlle. "Mécanismes et tenue mécanique long-terme de mousses polyuréthanes pures et renforcées aux températures cryogéniques." Phd thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2012. http://tel.archives-ouvertes.fr/tel-00740110.
Повний текст джерелаSchiavon, Isabelle. "Suivi de l'endommagement en fatigue d'un composite verre-époxyde unidirectionnel par mesures mécaniques et émission acoustique." Lyon, INSA, 1989. http://www.theses.fr/1989ISAL0022.
Повний текст джерелаRaphael, Ilan. "Fatigue-fluage du Polyamide 6,6 renforcé." Thesis, Paris, ENSAM, 2019. http://www.theses.fr/2019ENAM0048.
Повний текст джерелаThis work aims at completing the existing description and understanding of the fatigue behavior and damage mechanisms of short-glass fibers reinforced thermoplastic polymers.After a state of the art review the work focuses on the evaluation of fatigue and quasi-static damage mechanisms in SFRP as observed by micro-tomography and microscopy.In order to fully address the polymer damage mechanisms additional observations are performed on the neat polymer matrix and evidence a full scenario of intra-spherulitic fatigue damage growth.Microstructure modeling is used to complete the understanding of damage mechanisms accordingly to local mechanical fields.Based on the similarities of fatigue damage mechanisms with those observed for creep loading, a fatigue life assessment model based on the cyclic strain rate is introduced.It proved very effective at unifying the SFRP fatigue behavior over a wide range of loading conditions including R ratio effect, frequency effect, fiber orientation effect and humidity.The proposed criterion is also adapted for application to notched specimens and yielded promising results
Reynaud, Emmanuelle. "Etude des relations Structure : Propriétés mécaniques de thermoplastiques renforcés par des particules inorganiques nanoscopiques." Lyon, INSA, 2000. http://theses.insa-lyon.fr/publication/2000ISAL0070/these.pdf.
Повний текст джерелаThe works aims to correlate some morphological parameters and the mechanical properties in composite systems based on polymer matrix reinforced by submicronic inorganic fillers. The thought process lies on the study of three distinct filled polymer systems, their internal structure being all the more complex. The first system consists of a polymethyl methacrylate matrix filled with silica nanoparticles. The second system has polyamide 6 as a matrix and silica as fillers. The last system results from the clay introduction to polyamide 6/ First a morphological investigation enables to get insight into the filler influence on the surrounding polymer matrix. It also enlightens the various filler dispersion states (and its possible orientation within the sample geometry) with respect to the composite nature (in particular the inorganic particle size or its surface treatment) and its elaboration route. Then the study focuses on the role played by various morphological parameters (filler fraction, aspect ratio and dispersion state) on some mechanical properties, both elastic and plastic (through an investigation around the yield point). The latter properties were analysed on the various studied systems and compared. The experimental data were further confronted to some mechanical approaches, in order to better identify the morphological parameters leading to the observed macroscopic behaviours. Eventually, on the composites based on PA6, a possible sequence of the damage mechanisms occurring with increased elongation at room temperature was proposed, thanks to complementary experimental observations (through scattering and volume changes measurements). Given the involved parameters, each system was found to be characterised by a particular sequence of events
Mesmacque, Alexandre. "Étude de l'endommagement des polymères en transport pneumatique." Lille 1, 2005. https://pepite-depot.univ-lille.fr/RESTREINT/Th_Num/2005/50376-2005-326.pdf.
Повний текст джерелаCailleau, Pascal. "Effets thermiques et dommage mécanique au cours de la fatigue du polypropylène." Poitiers, 1996. http://www.theses.fr/1996POIT2275.
Повний текст джерелаFurtwengler, Pierre. "Synthèse et caractérisation de nouveaux synthons et mousses biosourcés, à partir de sorbitol." Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAE005.
Повний текст джерелаIn a context of renewable molecules valorization, new molecular architectures and polyols have been developed from sorbitol and various biobased building-blocks with respect to the green chemistry principles. Several polyesters polyol have been synthesized from controlled esterification reactions in bulk conditions. Thanks to the used of variable size diols (C2 to C12) monomers, polyols final viscosity and hydroxyls values were tuned until the obtaining of suitable properties for polyurethanes foams elaborations. Thus, semi-flexible polyurethane foams and rigid polyisocyanurate foams were formulated with fast foaming kinetic profiles (less than 3 min). Rigids polyisocyanurates foams exhibit excellent mechanical and thermal properties, in great agreement with building insulating application requirement. Otherwise, transesterifications reaction involving sorbitol and dimethyl carbonate were studied in order to develop a new bi-functional chemical platform, a bis-cyclocarbonate. Ring opening polymerization and aminolysis reactions were investigated from this chemical platform to the elaboration of cross-linked polyether and non-isocyanate polyurethanes (NIPU). NIPU syntheses were performed with short and long diamines in order to study the relationships between monomers choice and the resulting polymer material temperature of glass transition
Seignobos, Elodie. "Compréhension des mécanismes physiques de fatigue dans le polyamide vierge et renforcé de fibres de verre." Lyon, INSA, 2009. http://www.theses.fr/2009ISAL0090.
Повний текст джерелаGlass fiber reinforced polyamides are used in the automotive field thanks to their ligth weight in comparison to metals for the same rigidity. In order to study its durability, this material was tested in fatigue at different temperatures and stress vs fatigue lifetime curves (also called Wöhler curves) were drawn. We proposed a damage criterion based on the strain and therefore we normalized the Wöhler curves by the initial elastic modulus at the functionning temperature of the material. The master curve obtained enabled to predict the fatigue lifetime for a wide range of stresses and temperatures. Our study show that fatigue damage evolves in 3 phases. During the first step the material’s temperature increases and the damage is negligible. The second step is characterized by a stable temperature and a linear evolution of the apparent stiffness (called dynamic modulus in fatigue) and of the strain with the logarithm of the number of cycles. The sharp drop of stiffness during the third step is followed by the breaking of the composite. We show that lifetime is controlled by the duration of the second phase where t the material’s modulus decreases linearly with the logarithm of the time. Characterizations by X ray scattering, neutron scattering and electronic microscopy enabled us to study the fatigue damage from the nanometric scale to the micronic scale of the semi-crystalline structure of the reinforced polyamide and of the neat polyamide as a reference. The damage during the second step can be explained. We show that the drop of properties is due to low density domains nucleation in polymeric matrix at the nanometric scale, and to the increase of the number and of the size of these domains until the micronic scale. The size distribution, density and form factor of the domains have been quantified. We proposed a physical model for the nucleation of the domains based on the concept of heterogeneities of local strains. The activation energy has been estimated. This model is able to account for the logarithmic evolution of the macroscopic properties of reinforced and neat polyamide in fatigue. The results of this thesis opens the way to a better lifetime prediction in fatigue in one hand, and to an increase of the lifetime thanks to innovative formulations of polymer matrix in another hand
Garsot, Nikolaz. "Modélisation numérique du comportement mécanique des composites mousse métallique-polymère." Troyes, 2009. http://www.theses.fr/2009TROY0008.
Повний текст джерелаMetal foams have interesting properties for industrial purposes. Still, combining these foams with other materials can greater improve their properties. This work takes part in the development of composites consisted of metal foams and polymers. Its aim is to complete their mechanical and structural characterization which already begun several years ago. The results of this study highlight a strong relationship between the mechanical properties of the composites, the volume fraction, the nature and the morphology of constitutive materials. A model was developed to predict the mechanical behavior of the composites taking into account these interactions. A homogenization method was adopted using elasto-viscoplasticity models with non linear hardening coupled with isotropic ductile damage in the finite deformation framework. After the implementation in ABAQUS via user subroutine, this method was tested in two kinds of compression tests. Good agreements with experimental results were obtained: the macroscopic response, the damage initiation and propagation were correctly predicted. These are very promising for the applications to more complex loading cases by adding thermal and cyclic effects into the model
Ceglia, Gaétane. "Élaboration et caractérisation de matériaux polymères poreux modèles à base d’émulsions contrôlées." Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14462/document.
Повний текст джерелаPolymer foams are cellular materials commonly used for safety applications in many industrial sectors (aeronautic, passive safety, gears…). To even improve their performances, the link between their structural parameters (cell sizes, density...) and their mechanical behaviour should be better understood and modelled. A way of producing such foams is to polymerize the continuous phase of highly concentrated emulsions. The advantage of such an emulsion-based strategy is that it becomes possible to take advantage of the good control over emulsion parameters (drop size, dispersed phase volume fraction, continuous phase composition) to elaborate model foams with cells and pores having narrow size distributions. The production of model foams makes it possible to determine independently the influence of each parameter on the compression modulus and to compare the results with existing models
Goupillaud, Isabelle. "Comparaison des endommagements matriciels par fatigue mécanique et par cyclage thermique de composites structuraux : caractérisation et modélisation." Poitiers, 1998. http://www.theses.fr/1998POIT2332.
Повний текст джерелаBerrehili, Abdelmoutalib. "Comportement cyclique et tenue en fatigue sous chargement multiaxial d'un polyéthylène : expériences et critère d'endurance." Phd thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aéronautique, 2010. http://tel.archives-ouvertes.fr/tel-00517401.
Повний текст джерелаJulien, Jean Mario. "Développement de polymères et composites alvéolaires bio-sourcés à base de poly(acide lactique)." Phd thesis, Lille 1, 2011. http://tel.archives-ouvertes.fr/tel-00726158.
Повний текст джерелаSardelli, Francesco. "Aspects de la gravitation quantique à boucles : la représentation polymère, la jauge temporelle et lien entre approches covariante et canonique." Thesis, Tours, 2011. http://www.theses.fr/2011TOUR4050/document.
Повний текст джерелаNo summary available
Rattanapan, Suwat. "Preparation and Properties of Bio-Based Polyurethane Foam Prepared from Modified Natural Rubber and Poly(ε-caprolactone)". Thesis, Le Mans, 2016. http://www.theses.fr/2016LEMA1036/document.
Повний текст джерелаThe aim of this research was to prepare a bio-based polyurethane foam (PUF) containing hydroxyl telechelic oligomers from natural rubber (HTNR) and waste tire crumbs (HTWT) and polycaprolactone diol (PCL) as soft segments. The studied parameters included type of polyols and molar ratio between HTNR/PCL and HTWT/PCL. The molecular weight of HTNR and HTWT derived from 1H-NMR spectra were 1,800 and 1,400 g/mol, respectively. The molecular weight of PCL diol was 2000 g/mol. The effect of HTNR/PCL and HTWT/PCL molar ratio (1/0, 1/0.5, 1/1 and 0.5/1) on the foam formation rate and physical and chemical properties of the resulting PUF was investigated. The chemical structure of HTNR, HTWT and PUF were confirmed by FTIR and 1H-NMR. PCL diol provided faster reaction, thus higher PCL diol content showed higher foam formation rate. The foam density slightly changed with the molar ratio whereas the specific tensile strength of all samples was in the same range. The average diameter of cell increased with increasing contents of PCL diol. The addition of PCL diol resulted in reduced elongation at break and compressive strength. The cellular structure observed by SEM micrographs of HTNR based foams showed an almost closed cell. The biodegradability was assessed according to a modified Sturm test. Low density polyethylene and sodium benzoate were used as a negative and positive control sample, respectively. PUF samples showed an induction time of 33 days in which the percentage of biodegradation was 7-11%. The biodegradation of PUF containing only HTNR was 8.4% and 31.89% at 28 days and 60 days of testing respectively whereas the PUF containing 1/0.5 HTNR/PCL (by mole) showed a higher biodegradation: 11.31% and 45.6% at 28 days and 60 days of testing respectively. The molar ratio of HTWT/PCL strongly affected the kinetic rate of foam formation and foam morphology. According to SEM micrographs, polyhedral closed cells were observed. The addition of the PCL diol increased the thermal degradation temperature of the PUF based on TGA results. A low kinetic rate provided PUF with a high density, small cell size and a broad cell size distribution. The biodegradation of PUF containing only HTWT was 31.2% and 51.3% at 28 days and 60 days of testing respectively whereas the PUF containing 1/0.5 HTWT/PCL diols (by mole) showed a higher biodegradation: 39.1% and 64.3% at 28 days and 60 days of testing respectively. The foam formation rate of HTWT based PUF was higher than the one of HTNR based PUF. All HTWT based PUF have a higher density than HTNR based PUF. The HTWT based PUF had an inferior cell size in comparison to HTNR based PUF. The cellular structure of HTNR based and HTWT based PUF were different, but all PUFs showed almost closed cells. The HTWT based PUF had a higher thermal degradation temperature and biodegradation properties than foams from HTNR
วัตถุประสงค์ของงานวิจัยนี้ เพื่อทำการเตรียมโฟมพอลิยูรีเทนชีวภาพ (PUF) จากยางธรรมชาติดัดแปรที่มีหมู่ปลายไฮดรอกซิล (HTNR) ยางคลัมบ์ดัดแปรที่มีหมู่ปลาย ไฮดรอกซิล (HTWT) และพอลิคาโปรแลคโทน (PCL) ศึกษาผลของชนิดพอลิออล และสัดส่วนโดยโมลระหว่าง HTNR/PCL และ HTWT/PCL ที่สัดส่วน 1/0, 1/0.5, 1/1 และ 0.5/1 โดยโมล นํ้าหนักโมเลกุลของ HTNR, HTWT และ PCL ที่ใช้สำหรับงานวิจัยนี้ คำนวณจาก 1H-NMR คือ 1,800, 1,400 และ 2,000 g/mol ตามลำดับ ลักษณะโครงสร้างทางเคมีของ HTNR, HTWT และPUF สามารถวิเคราะห์และยืนยันด้วยเทคนิค FTIR และ 1H-NMR รวมถึงทำการวัดอัตราการก่อโฟม (Foam formation rate) ทดสอบสมบัติทางกายภาพ ทางเคมี และสมบัติการย่อยสลายทางชีวภาพ พบว่าในกรณีของโฟมพอลิยูรีเทนจาก HTNR/PCL เมื่อใช้ PCL ในปริมาณที่มากขึ้นจะส่งผลให้อัตราการก่อโฟมเร็วขึ้น และขนาดของเซลโฟมมีขนาดใหญ่ขึ้นด้วย ในขณะที่ค่าความหนาแน่น และความต้านทานต่อแรงดึงจำเพาะมีการเปลี่ยนแปลงเล็กน้อย การเติม PCL ในส่วนผสมของโฟมยังส่งผลให้ความสามารถในการยืด ณ จุดขาด และความทนทานต่อการกดมีค่าลดลง การคืนตัวหลังการกดของโฟม PUF2 (สัดส่วนระหว่าง HTNR/PCL = 1/0.5) จะให้ค่าตํ่าที่สุดคือ 40% ลักษณะของโฟมที่ได้จากการทดลองนี้โดยส่วนใหญ่จะเป็นแบบเซลปิด ความสามารถในการย่อยสลายทางชีวภาพของโฟม ทดสอบโดยใช้วิธี Sturm Test มี LDPE เป็นตัวเปรียบเทียบเชิงลบ และใช้ Sodium benzoate เป็นตัวเปรียบเทียบเชิงบวก พบว่าโฟมเริ่มมีการย่อยสายเกิดขึ้นอย่างเห็นได้ชัดที่เวลา 33 วัน มีเปอร์เซ็นต์การย่อยสลายในช่วง 7-11 เปอร์เซ็นต์ เปอร์เซ็นต์การย่อยสลายของโฟมจาก HTNR (PUF1) อยู่ที่ระดับ 8.4 และ 31.89 เปอร์เซ็นต์ และเปอร์เซ็นต์การย่อยสลายของโฟมจาก HTNR/PCL (1/0.5) อยู่ที่ระดับ 11.31 และ 45.6 เปอร์เซ็นต์ ที่เวลาในการทดสอบ 28 และ 60 วัน ตามลำดับ กรณีของโฟมพอลิยูรีเทนจาก HTWT/PCL เมื่อใช้ PCL ในปริมาณที่มากขึ้นจะส่งผลให้ค่าความหนาแน่นสูงขึ้น ขนาดของเซลโฟมลดลงมีการกระจายของเซลในวงกว้างไม่สมํ่าเสมอ เปอร์เซ็นต์การย่อยสลายทางชีวภาพของโฟมจาก HTWT (PUF5) อยู่ที่ระดับ 31.2 และ 51.3 เปอร์เซ็นต์ และเปอร์เซ็นต์การย่อยสลายของโฟมจาก HTWT/PCL (1/0.5) อยู่ที่ระดับ 39.1 และ 64.3 เปอร์เซ็นต์ ที่เวลาในการทดสอบ 28 และ 60 วัน ตามลำดับ เมื่อทำการเปรียบเทียบโฟมที่ได้จากการเตรียมโดยใช้พอลิออลหลักเป็น HTNR และ HTWT พบว่าโฟมจากพอลิออลหลัก HTWT ให้อัตราการก่อตัวของโฟมเร็วกว่า ขนาดของเซลโฟมเล็กกว่า ความหนาแน่น ความต้านทานต่อความร้อน และเปอร์เซ็นต์การย่อยสลายทางชีวภาพสูงกว่า เมื่อเทียบกับโฟมจากพอลิออลหลัก HTNR